Polym. J., 10(3), 315 (1974); Chem. Abstr., 83, 59483b (1975). (166) Schulz, G. V., Boehrn, L. L.. Loehr, G., Angew. Chem., lnt. Ed. Engl., 11, 340 (1972); Chem. Abstr., 82, 17210j (1975). (167) Seefried, C. G., Jr., Koleske, J. V., Critchfield, F. E., J. Appi. Polym. Sci., 19, 2493 (1975). (168) Seefried, C. G., Jr., Koleske, J. V., Critchfield, F. E., Dodd, J. L., Poiym. Eng. Sci., 15, 646 (1975). (169) Shepherd, I. W., Rep. frog. Phys., 38, (5), 565 (1975). (170) Siano, D. B., Applequist, J., Macromolecules, 8, 858 (1975). (171) Sircar, A. K., Am. Chem. SOC.,Div. Rubber Chem., October, 1976. (172) Sircar, A. K., Larnond, T. G., Rubber Chem. Technol., 48, 301 (1975). (173) h i d . , p 631. (174) ibid., p 640. (175) ibid., p 653. (176) Siowikowska, I.,Makaruk, L., Daniewska, I., Jedynak, M., Polym. J., 8, 221 (1976). (177) Smith, B. R., RubberChem. Technol., 49, 278 (19761. (178) Smith, K. J., Jr., Polym. Eng. Sci.. 16, 168 (1976). (179) Sorokina, M. F., Molyshev, A. I., lnt. Polym. Sci. Technol., 1(6), T42 (1974). (180) Spagnoio, F., Malone, W. M., J. Chromatogr. Sci., 14, 52 (1976). (181) Spatorico, A. L., J. Appl. Polym. Sci., 19, 1601 (1975).
(182) Spatorico, A. L.. Polym. Prep,., Am. Chem. Soc., Div. Polym. Chem., 15(1), 515-19 (1974). (183) Springer, P. W., Brodkey, R. S., Lynn, R . E., Polym. Eng. Sci., 15, 588 (1975). (184) Steichen, R . J., Anal. Chem., 48, 1398 (1976). (185) Stein, R. S., Polym. Eng. Sci., 16, 152 (1976). (186) Sullivan, A. B., Kuhls, G. H., Campbell, R. H.,Rubber Age, 108, (3), 41 (1976). (187) Surnan, P. T., Werstler, D. D., J. Polym. Sci., Polym. Chem. Ed., 13, 1963 (1975). (188) Supp,G. R., Gibbs, I., At. Absorpt. News/., 13, 71 (1974). (189) Swarin, S. J., Wirns, A. M.. Rubber Chem. Technol., 47, 1193 (1974). (190) Takaki, T., Bogue, D. C.. J. Appi. Polym. Sci., 19, 419 (1975). (191) Tanaka, Y., Sato, H., Ozeki, Y.. Ikeyama, M., Sato, T., Polymer, 16, 709 (1975). (192) Timm, D. C., Rachow, J. W., J. Polym. Sci., Polym. Chem. Ed., 13, 1401 (1975). (193) Tsuji, K., Konishi, K., Analyst(London), 99, 54 (1974). (194) Tsuruyo, T., Polym. J., 7(1), 62 (1975). (195) Tuzar, Z.,Petrus, V., Kratochvil, P., Makromol. Chem., 175, 3181 (1974); Chem. Abstr., 82, 58356e (1975). (196) Tymczynski, R., Tekely, P., Rocm. Chem., 50, 745 (1976). (197) Unger, K. K., Kern, R., Ninov, M. C., Krebs, K. F., J. Chromatogr., 99, 435 (1974).
(198) Vilenchek, L. Z.,Belen'kii, B. G., Nesterov, V. V., Kolegov, V. I., Vysokomol. Soedin., Ser. A, 17, 726 (1975); Chem. Abstr., 83, 59612t (1975). (199) Vohlidal, J., Bohackova, V., Matyska, B., J. Polym. Sci., Polym. Symp., (42), P t 2, 901 (1973). (200) Vondracek, P., Schatz, M., Sb. Vys. Sk. Chem.-Technoi. Praze, Org. Chem. Technol., C22, 85 (1975); Chem. Absh., 83, 1 4 8 7 0 8 ~ (1975). (201) Vrij, A., Van Den Esker, M. W. J.. J. Polym. Sci., Polym. Phys. Ed., 13, 727 (1975). (202) Wadelin, C. W., Morris, M. C., Anal. Chem., 47, 327R (1975). (203) Wallace, T. P., Cembrola, R . J., Migliore, A. J., Decann, D. E.,J. Colloid lnterface Sci., 51, 283 (1975). (204) Westfahl, J. C., Rubber Chem. Technol., 49, 417 (1976). (205) Wood, L. A., ibid., p 189. (206) Wun, K. L., Carlson, F. D.. Macromolecules, 8 , 190 (1975). (207) Wun, K. L., Feke, G. T. Prins, W., Faraday Discuss Chem. SOC.,57, 146 (1974). (208) Yearsley, F., lnd. Polym.: Charact. Mol. Weight., Proc. Meet., 1973, 39. (209) Yeh, G. S. Y., Polym. Eng. Sci., 16, 138 (1976).
Contribution No. 563 from The Goodyear Tire & Rubber Co., Research Laboratory, Akron, Ohio 44316.
Water Analysis M. J. Fishman" and D. E. Erdmann U.S. Geological Survey, Lake wood, Colo. 80225
This seventeenth review of the literature of analytical chemistry applied to water analysis covers the period from October 1974 through September 1976. The present review follows the plan of the previous reviews, the last of which appeared in Analytical Chemistry for April 1975 (9);however, the editors of Analytical Chemistry requested that the review authors cover their respective fields in a more selective manner and not attempt to provide an all-inclusive bibliography. The material used in preparing this review comes mainly from major analytical journals and United States Government publications. Conference proceedings, obscure foreign journals, and most trade journals are generally excluded. The summary of each article is shorter than in the past and the reader should refer to the publication cited for complete details. A review of the literature on water pollution control, which includes a section on analytical methods and instrumentation, is published annually by the Water Pollution Control Federation. The 1974 reviews by Brezonik ( 4 ) ,Suffet et al. ( l a ) , Minear et al. (12),and Olofsson and Ghosh ( 1 4 ) include 1295 references and cover such topics as major inorganics, trace inorganics, water characteristics, organics, continuous monitoring, automated analysis, and sampling procedures. The 1975 reviews by Brezonik and Carriker ( 3 ) ,Chlan and DeWalle ( 5 ) ,Ghosh and Olofsson ( I O ) , and Shuman and Fogleman (17) include 941 references and cover the same topics. Analytical techniques that have found widest application in the study of inorganic pollutants were compared by Coleman (6) on the basis of sensitivity, accuracy, precision, multielement capability, and range of application. Where possible, he discussed future trends in each technique. The techniques included microscopy, atomic spectroscopy, mass and x-ray spectrometry, neutron activation analysis, and electrochemical methods. Several analytical techniques for measuring and monitoring trace metals were reviewed by Minear (13).His review covered molecular absorption, molecular fluorescence, atomic absorption, and electrochemical techniques.
Phillips and Mack (15) reported on current commercial techniques and techniques being developed for measuring four major categories of water pollutants: metals, nutrients, pesticides, and oxygen demand. They limited their discussion to the most widely used techniques in water-quality monitoring: atomic absorption spectrometry, emission spectrometry, gas chromatography, gas membrane electrodes, and chemical oxidizers. Both manual and automated instruments for laboratory and field use are discussed. Birks and Gilfrich (2) in a general review of x-ray spectrometry devoted a section to its application to the field of water pollution. Elder, Perry, and Brady (8) reported that energy-dispersive x-ray fluorescence is a relatively recent development in the field of x-ray spectrometry that improves capability for rapid multielement analysis. Application of the technique to determine dissolved trace metals in water requires transfer of the dissolved elements to a uniform target suitable for analysis. This is accomplished by precipitating the elements with the nonspecific chelating agent, ammonium-1-pyrrolidine dithiocarbamate, and filtering through a membrane filter. DuCros and Salpeter (7) discussed automated methods for assessing water quality. Greater concern for water quality has caused significant increases in the analytical workloads of laboratories. The availability of automated wet-chemistry instrumentation and methodologies has provided these laboratories with the capability to analyze larger number of samples for more parameters more economically and more accurately than the use of manual methods permits. A review on the application of ion-selective electrodes in water analysis is given by Pungor and Toth (16).The types of electrodes and the theory of membrane electrodes are discussed, and determinations of various anions and cations are described. A spark source mass spectrometer that uses electronic detection and a dedicated data analysis system was applied by Taylor and Taylor (19) to multielement analysis of environANALYTICAL CHEMISTRY, VOL. 49, NO. 5, APRIL 1977
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mental samples. The system permits identification and quantitation of 27 elements a t the ppb level in water samples. Analytical methods for the study of water pollution were discussed by Baudin, Darras, and Roth (1).The possibilities and the orientation in determination of water pollution are illustrated by examples and a suggested analytical scheme. In the analysis of water, the detection limits to be attained and the complexity of the medium determine the analytical methods used. Three methods are described for the concentration of water: evaporation, solvent extraction, and ion exchange on resins. Four highly sensitive procedures that do not require concentration are described: fluorimetry, atomic absorption, spectrography, and neutron activation. Analytical methods for determining a number of metals in seawater by atomic absorption, anodic stripping, spark source mass spectrometry, and gas chromatography are discussed by Kampbell (11).
ALKALI METALS A N D ALKALINE EARTH METALS Eckfeldt and Proctor ( 3 A ) reported on the importance of sample flow velocity for measuring low levels of sodium with a glass electrode when continuously monitoring high purity process water. By using a flow channel of special design, which is described, conditions are established a t the electrode interface whereby the electrode is able to respond to fresh sample solution rather than to sample solution that has become altered by the presence of the electrode. The activation analysis by the looped-sample system was studied theoretically and experimentally by Tsuji, Fujiwara, and Kusaka (14A)and applied to the determination of sodium in seawater. The liquid sample is recirculated between the irradiation and counting cell, and the activity induced by irradiation with 14-MeV neutrons is measured continuously. Cattrall, Tribuzio, and Freiser, ( I A )examined the response characteristics of the potassium-selective electrode prepared by coating a platinum wire with valinomycin in poly(viny1 chloride). The electrode is used to determine potassium in seawater. Standards are measured before and after the sample, and the standards should be matched fairly closely to the sample itself. The sensitivity and limits of lithium detection by atomic absorption spectrometry and by flame emission spectrometry with air/acetylene and nitrous oxide/acetylene flames, and the anionic, cationic, and organic interactions influencing this determination were studied by Ecrement and Burelli ( 4 A ) . Lithium can be detected with flame emission spectroscopy with a strongly oxidizing air/acetylene flame to 0.5 ppb and can thus replace the more polluting sodium dichromate as a tracer in hydrologic investigations (evaluating the flow of water courses, effluents, dams leakages, etc.). An automatic flame emission spectrometer has been developed by Folsom et al. ( 5 A )for measuring traces of cesium in seawater with precision enough to demonstrate for the first time significant concentration variations of this element in the ocean. Complete details and diagrams are included. Analysis of test samples containing about 0.3 kg of cesium replicated better than 0.3%. Sekerka and Lechner (10A) determined simultaneously sodium and potassium in natural and waste water samples by direct potentiometry using sodium and potassium ion-selective electrodes. The results are printed out as concentration units directly from an automated continuous-flow system with on-line minicomputer and printer. The lower detection limits are 0.1 ppm for sodium and 1.0 ppm for potassium. The correlation of standard and proposed methods was reported to be very good. Isotope dilution mass spectrometry using double spikes was used by Murozumi and Nakamura ( 9 A )for successive determination of ppb levels of calcium and potassium in olar snow strata. The sample solution is spiked with 1 X 10- M potasM calcium-42. After establishment of sium-41 and 1 X isotope equilibrium, an aliquot of the spiked sample is loaded onto the ion source (tantalum single filament) of the mass spectrometer. Potassium in the calcium-42 spike solution and calcium in the potassium-41 solution were inevitable sources of error. The error range depends on the amount of the spike
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added. The method requires less sample than other methods. Ward and Biechler (15A) reported that calcium in water can be determined rapidly and accurately by atomic absorption spectrometry by dilution of the sample 1:l with 2000 pg/mL of sodium. This technique compensates for all common interferences except aluminum and silicon at levels greater than 100 mg/L. Results agreed with those obtained by EDTA titration on a number of water samples. An automatic amperometric determination of calcium and magnesium by complexometric titration is described by Kainz, Sontag, and Schoeller ( 8 A ) .Calcium and magnesium are determined in natural waters a t pH 10 by using a thallium oxide anode and EDTA and EGTA as titrating agents. Christiansen, Busch, and Krogh ( 2 A )reported on the successive determination of calcium and magnesium using an indicator electrode sensitive to the calcium ion and EDTA as the titrant in a solution containing 3,4-dihydroxybenzoic acid or acetylacetone. In this solution, the ratio between EDTA’s conditional stability constants for calcium and magnesium is increased so that two pronounced inflection points are obtained in the titration curve. The inflection points are determined in a stepwise, computer-controlled titration. Accuracy data are given. A technique to remove copper and iron prior to determining water hardness by the EDTA titration method is described by Fritz and King ( 6 A ) .Silica gel is reacted either with 3aminopropyltriethoxysilane or with the N-methyl derivative of the same reagent to produce a material with an amino silyl functional group. If a water sample in the pH range of 5.0 to 7.5 is passed through a short column of this material, iron(I1) and copper(I1) are completely retained, while calcium and magnesium pass through. Thompson (13A)reported that a water hardness electrode, while being used to measure magnesium activity in a series of copper-free solutions, displayed some unanticipated changes in potential. As the overall potential change observed for one solution was 183 mV (equivalent to more than six orders of magnitude change in magnesium ion activity), several precautions are suggested when using this electrode for specific purposes. In particular, the author recommended that the exchanger be pre-equilibrated with an appropriate solution if the electrode is to be used in restricted systems of known chemical composition. Total, noncarbonate, and carbonate water hardness have been determined simultaneously by Sekerka and Lechner (11A)by manual and automated direct potentiometry, using the bivalent ion-selective electrode, and known addition-known dilution technique. The automated and programmable system produces direct readout of total, noncarbonate, and carbonate water hardness. The optimum sampling rate is 20 samples per hour. Sixta, Miksovsky, and Sulcek (12A) described an atomic absorption spectrometric method that uses a two-stage separation for the determination of barium in strongly mineralized water. Barium is first coprecipitated with lead chromate, and then isolated and concentrated to a small volume by cation-exchange chromato raphy. As little as 5 wg/’L of barium can be detected. The metaod permits the determination of barium in water samples containing up to 40 g/L of sodium or potassium, 10 g/L of calcium, and 20 g/L of sulfate. Janouskova, Sulcek, and Sychra ( 7 A ) reported that flameless atomic absorption spectrometry could be used to determine as little as 0.05 ppb beryllium without preconcentration. Alkali metals do not interfere; however, sulfates have a mild depressive effect and magnesium a weak positive effect, but they do not compensate each other. Therefore, the calibration solution should contain corresponding amounts of sodium sulfate and magnesium sulfate.
IRON, MANGANESE, ALUMINUM, A N D CHROMIUM Rapid photometric methods for the determination of iron(I1) and iron(I1I) in water with 1,lO-phenanthroline were reported by Fadrus and Maly (5B,6B).Suppression of iron(111) interference in the determination of iron(I1) is accomplished with nitrilotriacetic acid (NTA). The intensity of iron(I1)-phenanthroline complex is then measured at 510 nm. Up to 100 mg/L of iron(II1) did not interfere. T o determine both species, iron(I1) is extracted after iron(II1) is masked with
Marvin J. Fishman, born in Denver, Colo., received his BA degree (1954) and MS degree (1956) from the University of Colorado. He has been employed by the Water Resources Division, U.S. Geological Survey. Denver, since 1956. His research interests are centered on development of methods for water analysis, including atomic absorption. He is a member of the Society for Applied Spectroscopy, and the American Society for Testing and Materials (Mr. Fishman serves on ASTM Committee D-19 on water). He has published about 30 papers related to methods for water analysis.
NTA; then the iron(II1)-NTA complex is destroyed, the iron(II1) reduced with ascorbic acid and the iron(I1) produced is determined after proper pH adjustments. Valcarcel, Martinez, and Pino (16B) used di-2-pyridyl ketone azine as an analytical reagent to spectrophotometrically determine iron(I1) in natural waters and industrial effluents. At p H 4.5 a green-colored complex is formed, which is extracted into chloroform, and the absorbance is measured at 750 nm. Beer’s law is obeyed between 1 and 6 ppm. Kornaga, Motomizu, and Toei ( 8 B ) reported on the extraction of the ternary complexes of iron(I1) nitrosophenolrhodamine B and the application of this technique to the spectrophotometric determination of trace amounts of iron(I1) in water. The method is very sensitive and selective for iron(11);however, the procedure involved is troublesome because of the need to extract the iron from aqueous solution. In a subsequent paper Toei, Motomizu, and Kornaga (14B) investigated a number of nitroso compounds for directly determining iron in the aqueous phase. Nitroso dimethylaminophenol was found to be an excellent reagent for iron(I1) and a procedure for its use in natural waters is given. Trofimov et al. (15B)described a highly selective and sensitive photokinetic method for determining iron(II1) in water by oxidizing Redoxan I1 leuco base with hydrogen peroxide. The effect of other substances was investigated. A flow-through system using repetitive colorimetric determinations, based on injection of the sample containing the sought-for species into a continuously circulated reagent mixture, is described by Dutt, Eskander-Hanna, and Mottola (4B). Practical application of the approach is illustrated with the determination of iron in water using FerroZine. A simple and rapid colorimetric test for determining iron(I1) in water was developed by Tanaka, Hiiro, and Kawahara (I3B).Iron concentrations between 0.1 and 5.6 ppm are determined either visually or photometrically a t 540 nm by immersing a transparent poly(viny1 chloride) film of approximately 0.3 mm thickness, impregnated with bathophenanthroline and butyl phosphate, in the test solution in _thepresence of sodium perchlorate. A fully automated method for the preparation of surface water samples for Lotal inorganic iron analysis by atomic absorption spectrometry and a method for the aspiration of the prepared samples are described by Pierce, Brown, and Fraser ( I 1 B ) . The system will handle 60 samples per hour and is flexible as to sampling rates, sample-digestion solution ratios, added chemicals, and time for particulate settling. The preparation of a hydroxamized cellulose powder as a chelating agent and its analytical potential for selectively extracting iron(II1) from seawater was studied by Kotsuji e t al. (PB). Shigematsu et al. (12B)determined manganese in natural waters by atomic absorption spectrometry with a carbon-tube atomizer. Various inner diameters of the carbon tubes were tested: small bores gave higher sensitivity, but large bores gave higher reproducibility. A nearly linear calibration curve was obtained in the range of 1-6 X g manganese with a 5-pL sample. In 40-fold amounts, few salts interfered, but there were considerable interferences from 400- and 4000-fold amounts. Eriochrome cyanine R, stilbazo, and catechol violet, which had not been used previously for the determination of aluminum in water, were compared by Dougan and Wilson ( 3 B ) .
Davld E. Erdmann has been a chemist with the Water Resources Division of the U.S. Geological Survey since 1968. He received his BS degree from Winona State College and his MS and PhD degrees from the University of Nebraska. His research interests are concerned with the development and automation of methods for water analysis. He is a member of the American Chemical Society, Sigma Xi, and Phi Lambda Upsilon Societies.
Catechol violet was the most suitable, and aluminum was determined in the 0-3 mg/L range at p H 6.0-6.2 using a hexamine buffer in the presence of 1,lO-phenanthroline. As little as 0.003 mg/L could be detected. Fluoride did not significantly interfere a t a level of 1mg/L; larger concentrations interfere and can be removed by fuming with sulfuric acid. Condensed inorganic phosphates were hydrolyzed prior to analysis to minimize their interference. A rapid, simultaneous determination of picogram quantities of aluminum and chromium in water by gas phase chromatography was described by Gosink ( 7 B ) .The trifluoroacetylacetonate chelates of aluminum and chromium are formed in order to determine the metals. Details on the material and the preparation of the columns are given. A method for the determination of chromium in natural waters by gas chromatography was developed by Lovett and Lee (IOB). The chromium is chelated with trifluoroacetylacetone and the chelate is extracted into benzene. The extract is injected into a chromatograph using an electron capture detector. A detection limit of 0.1 pg/L was found. A method utilizing differential pulse polarography for the determination of chromium(V1) in natural water is described by Crosmun and Mueller ( 2 B ) . Additions of 0.62 pg/mL of copper(I1) and 0.55 pg/mL of iron(II1) did not interfere with the determination of 0.050 pg/mL of chromium. The natural water samples containing chromium(V1) are buffered to approximately p H 7 and analyzed. The detection limit is 0.010 pg/rnL. The centrifugal fast analyzer was adapted by Bowling et al. ( I B ) for the chemiluminescent determination of chromium(II1) and, after reduction, chromium(V1) by catalysis of the luminol-peroxide reaction in basic medium. From 50 to 600 ppb can be determined with a relative standard deviation of 1to 2%.
COPPER, ZINC, LEAD, CADMIUM, NICKEL, A N D COBALT Shigematsu et al. (32C) used a carbon tube atomizer with an atomic absorption spectrometer to determine copper in seawater. The carbon tube temperature, argon flow rate, calibration curve, and the interference of diverse ions were studied. The copper is extracted prior to atomization as the diethyldithiocarbamate complex into diisobutyl ketone. Edwards and Oregioni ( I O C ) described a method to extract and concentrate copper from seawater by anodic stripping voltammetry. The copper is reduced onto a thin mercury film deposited on a wax-impregnated graphite tube. The copper is then completely stripped out of the mercury into a small volume of water that is then analyzed for copper by flameless atomic absorption spectrometry. Tinsley and Iddon (34C) determined copper in the 10- to 100-ppm range by a solvent extraction and an atomic absorption procedure involving the use of the liquid-ion exchange Amberlite LA 2 in thiocyanate form. The square-wave polarographic determination of copper in seawater by coprecipitation with zirconium hydroxide was investigated by Yoshirnura (41C).The precipitate is dissolved in 2 M hydrochloric acid, and copper determined in 1 M hydrochloric acid at -0.25 V vs. the mercury pool electrode. Iron(II1) and bismuth interfere. A direct current polarographic ANALYTICAL CHEMISTRY, VOL. 49, NO. 5, APRIL 1977
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method for determining copper in contaminated seawater was reported by Klein and Pennington (16C). Sugawara, Ozawa, and Kambara (33C) used zincon to spectrophotometrically determine ppb levels of copper. Hydrogen peroxide and manganese(I1) ion are added to copper(I1)-zincon complex causing the absorbance of the excess zincon to decrease because of decomposition; whereas, that of the complex is constant for at least 80 min. The ion pair, extracted with chloroform after decomposition of excess zincon and addition of zephiramine, has an absorption maximum at 623 nm. Akaiwa, Kawamoto, and Izumi ( I C ) prevented the interin the ference of residual l,l,l-trifluoro-3-(2-thenoyl)acetone determination of copper by first adding the reagent in chloroform to the aqueous solution at pH 5.4. The excess reagent is then scrubbed from the organic phase with 0.005 M sodium hydroxide and the absorbance of the copper complex measured at 344 nm. Almost complete removal of the residual reagent is obtained and decomposition of the copper complex is negligible. A highly selective catalytic method was described by Rychkova and Dolmanova (30C) for the determination of 2 x pg/mL of copper in feed water using the hydroquinone-ammonium fluoride-hydrogen peroxide reaction at pH 7.1 to 7.3. Optimum conditions are given. The absorbance is read a t 420 nm. Murozumi and Abe (28C) used isotope dilution to determine copper in seawater. Measurement of 6 3 C ~and f s5Cu+ ion beam intensity is carried out by a surface ionization mass spectrometer using a single Re filament. Copper is extracted as the dithizonate into chloroform and then evaporated with nitric and perchloric acids and taken up in sulfuric acid prior g of to the measurement. The detection limit is 1 X copper. Blutstein and Bond (5C) reported that for a wide range of natural water systems, trace amounts of zinc can be determined directly in acidic media by differential pulse anodic stripping voltammetry a t a hanging drop mercury electrode. Cadmium, copper, and lead also can be determined directly and simultaneously on the acidified sample. Le Bihan and Courtot-Coupez (22C) determined zinc in seawater by flameless atomic absorption spectrometry, after elimination of chloride by evaporation as hydrochloric acid during the drying period in the graphite furnace. Maines, Aldous, and Mitchell (26C) determined lead in potable waters using a Delves cup in combination with an atomic absorption spectrometer. The procedure has a detection limit of 5 Fg/L of lead and the calibration curves are linear to 200 Fg/L. For most potable waters, the method of standard addition gave better results. Goto (13C) used atomic absorption spectrometry to determine lead in river water and plant samples by extraction with high molecular weight amines. Lead is extracted from 0.3 M potassium iodide-0.2 N hydrochloric acid with three volume percent Amberlite LA-1 (chloride form) in xylene. The analytical curve is linear between 10 and 140 pg of lead. Chromium(V1) interferes significantly. Regan and Warren (29C)described a method to eliminate matrix interferences when determining lead in water by flameless atomic absorption spectrometry. Matrix interferences were reduced by thermolysis of an aqueous sample solution containing ascorbic acid, tartaric acid, or sucrose, which gives a molecular mixture of carbon and sample to assist in formation of atomic va or. Hirao (14C) reportei on the determination of trace concentrations of lead in natural waters by isotope dilution mass spectrometry. A lead-208 spike is added to a sample solution and, after isotopic equilibration, lead is extracted with dithizone-chloroform solution at pH 7.5-8.5. The sample is then mounted on a Re filament with silica gel and phosphoric acid and measured. Tominaga et al. (35C) made a detailed study of the determination of cadmium by flameless atomic absorption spectrometry using a heated graphite atomizer. Magnesium, copper, iron, cobalt, and nickel as chlorides interfere seriously, even at the 1000-fold level. For the determination of cadmium in complex samples, two simplified standard addition methods are proposed. Lund and Larsen ( 2 4 C ) described a simple flameless atomic absorption technique to determine sub-ppb levels of cadmium in seawater. The metal is first electrolyzed 142R
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for 5 min on a thin tungsten wire, and then atomized by electric heating of the filament within an absorption cell. The results agreed with data obtained by anodic stripping voltammetry. The solvent extraction of cadmium(I1) from hydrochloric acid into a tri-n-octylamine-cyclohexene mixture was studied by Topping and MacCrehan (36C). This system was used as the basis for the development of a reversed-phase column chromatographic technique for preconcentrating cadmium prior to determination by conventional flame atomic absorption spectrometry. With this system, cadmium in acidified water samples as large as 3 L may be concentrated to 10 mL. A neutron activation technique was used by Weiss et al. (37C) to determine cadmium in seawater by measurement of radio-induced 115Cd-1151n.Complete details of the procedure are given. The processed cadmium samples and standards are irradiated for 20 s in a flux of 3 x 1012 n/cmz/s. After 24 h, the a rays of l15Cd-1151n are measured with a sodium iodide (thallium) detector coupled to a pulse height analyzer. A number of investigators during the past 2 years described simultaneous methods for two or more of the elements discussed in this section using anodic stripping voltammetry and other polarographic techniques: Anderson and Tallman ( 2 C ) , Cd, Pb, and Cu; Barnes et al. ( 3 0 ; Ben-Bassat et al. ( 4 C ) ,Zn, Cd, Pb, and Cu; Crosmun, Dean, and Stokely (9C), Zn, Cd, and Pb; Gardiner and Stiff (12C),Cd, Pb, Cu, and Zn; Lund and Salberg (25C),Cu, Pb, and Cd; and Miguel and Jankowski (27C),Cu and Pb. Frimmel, Roeder, and Quentin (11C)determined cadmium, nickel, and lead in concentrations from 0.024 to 12 mg/L using a Davis 2-cell cathode ray polarograph. Yasuda and Kakiyama (40C) determined trace amounts of copper and lead in river and industrial waste waters by direct flameless atomic absorption spectrometry. Interferences are discussed. The limits of detection are 0.2 ppb for copper and 0.4 ppb for lead. Flameless methods for the determination of cadmium, lead, and zinc are described also by Jensen, Dolezal, and Langmyhr (15C).The metals are separated from the salt matrix on a hanging mercury drop electrode, the mercury is transferred to a graphite boat and removed by evaporation, and the metals are atomized. Sato, Oikawa, and Saitoh (31C) used ion-exchange resin to separate copper, cadmium, and lead from estuarine water prior to flameless atomic absorption spectrometry. Yamamoto et al. (39C)determined ppb levels of cadmium, lead, and copper in river and seawater by carbon-tube flameless atomic absorption spectrometry after the metals were extracted with dithizone-carbon tetrachloride. Briese and Giesy (6C) reported on the determination of lead and cadmium associated with naturally occurring organics extracted from surface waters using flameless atomic absorption spectrometry. Matrix interferences in the determination of cadmium are reduced by optimization of charring temperature and time. Addition of 50% ammonium nitrate and 1%nitric acid eliminated matrix interference in the determination of lead. Methods that make it possible to separate ppm levels of copper, zinc, lead, cadmium, and cobalt from natural waters by ion exchange prior to determination by atomic absorption spectrometry are described by Korkisch, Goedl, and Gross (19C, 20C); Korkisch and Sorio (18C,21C); and Korkisch and Goedl (17C).Details of the methods are given in each of the papers. An analytical scheme is given by West and West (38C)for the separation and concentration of copper, cadmium, and zinc from waters. The ring-oven technique is used for the final step of concentration and measurement. The method should be useful for field studies and as a screening device to determine compliance with standards. Leyden, Patterson, and Alberts (23C) prepared an ionexchange resin from tetraethylenepentamine and toluene diisocyanate and used it in a small column to preconcentrate copper, nickel, and zinc from seawater. The resin is then compressed into a tablet and the metals are determined by x-ray fluorescence. Catanzaro (8C) used a simple isotope dilution technique to determine lead and copper in natural waters. The metals are electroplated on platinum wires; copper on the cathode and the lead oxide on the anode. They are then stripped with different acids and concentrations are determined separately by mass spectrometry.
A method is described by Bruninx and Van Meyl (7C) to measure, by x-ray fluorescence, zinc and lead in surface waters a t concentrations of 10-100 pg/L. Zinc and lead are first coprecipitated on iron hydroxide.
MERCURY AND GOLD El-Awady, Miller, and Carter ( 3 0 ) developed an automated atomic absorption cold-vapor method to determine total and inorganic mercury in water and waste water. A detection limit of 0.05 pg/L is obtained by the use of a highly sensitive spectrometer. The use of potassium persulfate, potassium permanganate, and potassium dichromate, and mixtures of these salts as oxidizing agents for the digestion step is discussed, and a study of sample preservation using nitric acid-potassium dichromate is given. Twenty samples per hour can be analyzed. Nishimura, Matsunaga, and Konishi ( 1 9 0 ) determined nanogram levels of mercury in water by flameless atomic absorption spectrometry after preconcentration. Stannous chloride is added to a large volume of an acidified sample and the mixture is allowed to stand for 3 weeks or more. The mercury is then collected on porous silver metal by bubbling nitrogen through the sample. The amount of mercury on the silver is then measured. A cold-trap preconcentration procedure was developed by Fitzgerald, Lyons, and Hunt ( 5 0 ) and incorporated into a standard flameless atomic absorption method for determining mercury in seawater and other environmental samples. The cold trap is created by immersing a glass U-tube packed with glass beads in liquid nitrogen. After reducing, purging, and trapping, the mercury is removed from the glass column by controlled heating and is measured. Baltisberger and Knudson (ID)described a method to differentiate ppb amounts of inorganic and organomercury compounds in water by flameless atomic absorption. Inorganic mercury is determined in a sulfuric acid media with a stannous(I1) salt. The total mercury is determined after oxidation with hydrogen peroxide. Svistov and Turkin ( 2 2 0 ) determined mercury in waste water with 0.05 bg/L sensitivity and approximately 10%reproducibility by heating the sample with nitric acid and potassium dichromate a t 100-120 "C, electrolyzing at 10 mA and 3 V between platinum and copper electrodes, and analyzing the platinum anode wash by atomic absorption. Hawley and Ingle ( 8 0 ) made modifications to the normal apparatus used for the cold vapor atomic absorption determination of mercury in water. They reduced the dead volume of the apparatus, increased the efficiency of diffusion of elemental mercury into the carrier gas, and optimized the instrumental parameters. The analysis time, sample volume, and detection limit are greatly reduced. The detection limit is 0.05 ppb of mercury. Hinkle and Crenshaw ( 1 0 0 ) determined elemental and ionic mercury in natural water, plants, soils, rocks, and sediments by a cold vapor absorption method. Robertson ( 2 1 0 ) determined mercury in seawater samples by ultraviolet absorption of vaporized mercury atoms. Heinrichs ( 9 0 ) described a flameless atomic absorption method to determine mercury in rocks, coal, and water. Elemental mercury is absorbed on gold. The gold is then heated in a graphite atomizer and the vaporized mercury measured. A simple system for determining mercury in natural water by the cold vapor technique with commercial atomic absorption spectrometers is described by Ramelow and Balkas ( 2 0 0 ) . A method was developed by Kiemeneij and Kloosterboer ( 1 3 0 ) for the determination of total mercury in water in the ppb range. Organomercurials are decomposed by ultraviolet radiation from small, low-pressure lamps containing either zinc, cadmium, or mercury, or a mixture of these metals, in their cathodes. Irradiation times are approximately 20 min. The inorganic mercury formed is then determined by normal cold vapor techniques. Hori and Kobayashi ( 1 2 0 ) described a vapor detector tube that was used to determine mercury in the range of 1 to 14 p g L . The apparatus consists of a 100-mL gas washing vessel, a glass tube, and an aspirator. A mixture of silica gel, 40-60 mesh, and cupric iodide is placed in the tube. The mercury vapor is sucked into the tube and mercury determined by the empirical relation between the length of stain and mercury concentration.
A procedure for determining mercury concentrations between 5 and 500 ng/L was reported by Le Bihan and Courtot-Coupez (150). The method involves the formation of mercury pyrrolidinecarbodithioate complex and the extraction of the complex with propylene carbonate. The extracted mercury is reduced in the solvent by stannous chloride and the elemental mercury determined by flameless atomic absorption spectrometry. Vitkun et al. ( 2 5 0 ) determined mercury in water by atomic absorption spectrometry after concentration of the mercury. Air or an inert gas is bubbled through the sample and, subsequently, through a small volume of iodine in aqueous potassium iodide. The absorbed mercury is then reduced to the elemental state with an alkaline ascorbic-acid solution. Watlin ( 2 6 0 ) determined mercury at sub-ng/L levels in seawater gby microwave-excited argon plasma emission that utilized an amalgamation stage where mercury released from water samples by stannous chloride reduction is amalgamated onto silver wool. The wool is then heated and the mercury is flushed by argon into a plasma where i t is excited. Miyazaki and Umezaki ( 1 7 0 ) used a direct-current plasma arc to determine mercury in water. The mercury is reduced by stannous chloride and swept directly with argon into the plasma. They reported that large amounts of silver, selenium, nitrite, iodide, sulfide, and thiosulfate inhibit the evolution of the mercury vapor. A gas chromatograph with a microwave emission spectrometer detector was used by Talmi ( 2 3 0 ) to determine trace amounts of volatile organomercury compounds in environmental samples. The relative sensitivity for methyl mercuric chloride is 1 n g L . Hobo et al. ( 1 1 0 ) described a gas chromatographic technique to determine ppb-levels of methyl mercuric chloride in water. The organomercury compound is concentrated 150-300 times by foaming the water sample in a cylinder with nitrogen in the presence of potassium n-butylxanthate and cetyltrimethylammonium bromide. The foam is collected in a small amount of butyl alcohol, extracted with benzene, and analyzed. Heavy metals interfere but are removed by Amberlite IR-120A and IR-4B. Kraemer and Neidhart 1140) reported that an aniline sulfur resin is an effective matrix for the selective preconcentration of dissolved mercuric nitrate and methyl mercuric chloride from aqueous solution. Mercury can then be determined by neutron activation analysis. A sensitive neutron activation analysis procedure for the determination of mercury in sea and surface water is presented by Van de Sloot and Das ( 2 4 0 ) . Inorganic mercury is isolated by reduction and volatilization followed by absorption on a charcoal column. Total mercury is determined by absorption from the solution directly onto a column of charcoal. The limit of detection is 1ng/L. A nonflame atomic fluorescence system with a detection limit of 5 pg mercury was developed by Hawley and Ingle ( 7 0 ) . The system is useful for the determination of residual mercury levels in water. The relative precision is 5% or better above 50 pg mercury and the range is linear from 0 to 100 ppb. Fitzgerald and Lyons ( 4 0 ) stated that a PVC sampler was suitable for collecting seawater samples for mercury. Bothner and Robertson ( 2 0 ) reported that mercury concentrations increased in seawater and distilled water samples that were placed in polyethylene bottles, acidified to p H 1.5 with hydrochloric acid, and stored at room temperature under certain conditions. No changes were observed in ground-glass stoppered Pyrex flasks. When the polyethylene bottles were stored in a sealed plywood box, the mercury concentration was unchanged for 40 days; whereas, the concentration increased for identical bottles stored on the laboratory floor. Gaston and Lee ( 6 0 ) stored samples of organic and inorganic mercury a t 1 pg/L levels for about 4 weeks when the samples were adjusted to a p H of 1.0with nitric acid or a t p H 1.0, 2.0, and 3.0 with excess potassium permanganate. The difference between flint-glass and high-density polyethylene bottles was not significant. Lo and Wai ( 1 6 0 ) studied a number of preservation techniques for storing mercury in polyethylene bottles for a period of 21 days. When no preservative was added, 95% of the mercury was lost; 77% by adsorption on the walls and 18%by volatilization. The best preservatives, with only a 2% loss, were 0.05% potassium dichromate plus nitric acid a t p H 0.5 and gold(III), 0.2 ppm, plus nitric acid a t pH 0.5. Weiss, Shipman, and Guttman (270) determined the effect of several different conditions on the mechanism of mercury losses from ANALYTICAL CHEMISTRY, VOL. 49, NO. 5, APRIL 1977
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solutions in polyethylene bottles. They stated that natural waters can be stablized against such losses by the addition of a relatively small quantity of cysteine. Musha and Takahashi ( 1 8 0 ) described a method for enrichment of trace amounts of gold in water utilizing the coagulation of soybean protein and its determination by atomic absorption spectrometry and emission spectrography. Gold is determined in the range of 0.01 to 1 ppb.
MOLYBDENUM, VANADIUM, TUNGSTEN, URANIUM, THORIUM, AND THALLIUM Kim, Alexander, and Smythe ( 7 E ) described, a method using long-chain alkylamines for preconcentration of molybdenum from large volumes of natural waters. Molybdenum is extracted as the thiocyanate complex by 0.2% Aliquat 336 in chloroform, followed by solvent evaporation, dissolution into methyl isobutyl ketone, and determination by atomic absorption spectrometry. Korkisch, Goedl, and Gross (IOE)determined molybdenum in natural waters after separation by ion exchange. The sample is acidified with hydrochloric acid, filtered, and after addition of potassium thiocyanate, is passed through a strongly basic ion-exchange resin. The molybdenum is eluted with perchloric-hydrochloric acid, evaporated to dryness, and determined by atomic absorption. Morgen, Rossinskaya, and Vlasov (16E) reported that molybdenum(V1) forms a 1:2:2 complex with pyrogallol red and dimethyldioctadecylamnionium. A spectrophotometric method is presented for the determination of molybdenum in water. Interference from iron is eliminated by adding phosphate ion. If vanadium and tungsten are present, the molybdenum is first extracted with a-benzoinoxime in the presence of potassium dihydrogen phosphate and Mohr salt. After separation of molybdenum from seawater by ion exchange, Kuroda and Tarui (1323) determined traces of molybdenum in the range of 0.01 to 0.3 pg/mL by its catalytic activity on the reduction of the iron(II1) tartrate complex with stannous chloride. Muzzarelli and Rocchetti ( I 7 E ) studied the anion-exchange behavior of chitosan toward metavanadate in salt solutions a t different pH values. Filtered and acidified seawater is passed through a 500-mg chitosan column and vanadium is determined by atomic absorption spectrometry with a graphite furnace and a deuterium background corrector on 5-mg aliquots of the homogenized column. Ohta et al. (18E) spectrophotometrically determined vanadium in seawater after coprecipitation with ferric iron and reaction with N-benzoyl-N-phenylhydroxylamine. Iron(II1) need not be removed. Korrey and Goulden (12E) used solvent extraction and atomic absorption spectrometry to determine tungsten a t levels greater than 100 pg/L in natural waters. Tungsten is complexed with benzoin anti-oxine and extracted into methyl isobut 1 ketone. The extract is aspirated into a nitrous oxideicetylene flame. Mihalik (15E)determined microgram quantities of uranium in water spectrophotometrically at 643 nm with Arsenazo I11 at p H 2 after separation by adsorption on active coal. Thorium interference is masked by addition of sodium fluoride, and zirconium, potassium, and chromium interferences are masked by addition of Chelation 3. The accuracy of the determination is approximately 5% in the range from 1to 10 pg/L. Zharov (23E)used a similar method to determine uranium in water, rocks, and plants. Korkisch and Steffan (11E) and Korkisch and Goedl (8E, 9 E ) reported that fluorometric and spectrophotometric methods can be used for the determination of uranium in natural waters after preliminary isolation by adsorption of its thiocyanate complex on strongly basic anion-exchange resin. Dowex 1is useful also for analysis of waters with high salt content, such as seawater. Sekine (20E)applied froth flotation to separate ppb concentrations of uranium in seawater. After separation, uranium is determined by either neutron activation or spectrophotometry using Arsenazo 111. Van der Sloot, Massee, and Das (21E)determined uranium in sea and surface water samples by neutron activation after preconcentration on charcoal. Gladney, Owens, and Starner ( 4 E ) developed a rapid procedure for the measurement of uranium in natural waters using thermal neutron activation 144R
ANALYTICAL CHEMISTRY, VOL. 49, NO. 5, APRIL 1977
after anion-exchange separation of uranium from ethanolhydrochloric acid solvent mixtures. The detection limit is 0.05 ppb. Weaver (22E) determined uranium in concentrations greater than 25 ppb by a 4- to 8-h irradiation in a flux of 3 x 1013 neutrons/cm2/s. After a 48-h decay, the 1331activity is measured with a low-energy photon detector coupled to a multichannel analyzer. A semiquantitative determination of uranium, plutonium, and americium in seawater is described by Hodge and Gurney (6E). These constituents are first precipitated with sodium hydroxide, the precipitate is centrifuged, and then dissolved with 12 M hydrochloric acid. The solution is neutralized with ammonium hydroxide to a p H of 2-3 and the uranium, plutonium, and americium are electrodeposited on a stainlesssteel planchet for counting. McDowell, Farrar, and Billings ( 1 4 E ) determined uranium and plutonium by a combined high-resolution liquid scintillation-solvent extraction method. The construction of a high-resolution liquid scintillation detector is also described. Fleischer and Delany (3E)stated that individual droplets of water can be analyzed for uranium down to less than 0.01 pg/L using readily available neutron doses. By separately counting randomly arrayed and clustered tracks, the dissolved uranium can be separated from that which is suspended in particulate matter. Reimer (19E)reported that uranium loss can be avoided if the samples are frozen after collection. The frozen samples are analyzed by the fission track technique. Hathaway and James (5E) used chelating ion-exchange resin (Chelex-100) and x-ray fluorescence to determine uranium in alkaline earth-bicarbonate-type ground waters. The uranium is determined directly on the resin. The detection limit is 2 ppb. A chromatographic-a-spectrometric technique is described by Bogdanov and Kuznetsov ( 2 E )for determining uranium in sea and mineral waters. Complete details of the procedure are given in the abstract. Adamek and Chiryat’ev (1E)described an isotope dilution method using substoichiometric displacement for the determination of thallium in a wide concentration range. Thallium is displaced from a thallium-dithizone complex by mercuric ion. Concentrations greater than 0.01 bg/mL can be determined. Results are comparable to those obtained by emission spectrometry and photoactivation analysis.
BORON, PHOSPHORUS, AND SILICA Bikbulatov ( 2 F ) compared potassium persulfate and ultraviolet radiation for the oxidation of organic-phosphorus substances in natural water. He reported that both methods gave the same results for waters with many different organic substances. With ATP and DPN, the oxidation by the photochemical method is incomplete. The author recommends the potassium persulfate method. Nicholls (15F) used a single acid-peroxide method to determine total nitrogen and phosphorus in natural water. The digested sample is neutralized before determining phosphorus. An improved molybdate blue method for determining phosphorus in seawater was reported by Hosokawa and Ohshima (IOF).A reagent that contains both molybdenum(VI) and molybdenum(V) is used and is prepared by the reduction of molybdenum(V1) with metallic zinc in an acid medium. The reagent is stable in the air for several months, and the development of the molybdenum blue color is complete in 20 min at approximately 100 O C ; the color is stable for at least a few months. Mackay (148’) determined low levels of phosphorus in fresh water by a variant of the heteropoly blue method using extraction with isobutanol to lower the detection limit t o 0.001 mg/L. Awad and Kretzschmar ( I F ) described a spectrophotometric method for determining phosphate in surface and waste waters. The sample is ultrafiltered, the humic acids are precipitated by addition of 4 N sulfuric acid, and, if necessary, the water is centrifuged at 3000 rpm to obtain a clear sample. Phosphate is determined as the yellow vanadate-molybdate complex. An automated method is described by Goulden and Brooksbank (8F)for eliminating arsenate interference in the determination of phosphate in natural waters by the molybdenum blue method. The arsenate is reduced to arsenite by
thiosulfate in an acidic medium before the color-producing reagents are added. Goulden and Brooksbank ( 9 F ) also described both semiautomated and fully automated methods for determining total phosphate in natural waters. The semiautomated method involves autoclaving the sample in culture tubes with acid persulfate solution at 15 psig for 30 min. The fully automated method uses ultraviolet digestion. Both methods incorporate automated steps to remove interference from arsenic and to extract the molybdenum blue color. The methods are designed for waters containing 0.24.0 pg/L of phosphorus. An automated system for the determination of total phosphorus and total kjeldahl nitrogen in water, that uses a helix digestion system and a mixture of sulfuric and perchloric acids, and V205 as a catalyst, was described by Gales and Booth (6F).The applicable range is 0.10 to 10 mg/L of nitrogen and 0.02-1.0 mg/L of phosphorus. A semiautomated method is reported by Canelli and Mitchell ( 5 F ) for the determination of phosphorus in water, waste waters, and particulates. The phosphorus compounds are first oxidized by peroxydisulfate digestion and then the orthophosphate is determined by the automated molybdenum blue method. Ramirez-Munoz (18F) described a colorimetric method for determining low levels of phosphate in water using an automatic discrete-sample analyzer. Two methods based on the formation of molybdenum blue are presented. Sixty samples can be analyzed per hour. Leyden, Nonidez, and Carr (13F) used x-ray fluorescence spectrometry to determine ppb levels of phosphate in natural waters. The phosphate is converted first to 12-molybdophosphoric acid and then extracted into ethyl acetate. The germanium, silicon, and arsenic acid compounds, which are contaminants, are not extracted. The 12-molybdophosphoric acid is then adsorbed onto silica gel that contains N-substituted diamine functional groups. The silica gel is pressed into pellets and the K a line of the molybdenum is measured. The standard working curve extends from 0 to 3000 ppb. By using activation by 16 MeV a-particles, Vis and Verheul (24F) determined phosphorus in natural waters with a reproducibility of f5%. The limit of detection is 0.1 ppm. Seitz (19F) evaluated flame emission spectrometry for the determination of phosphorus in water. The spectrometric response in the form of phosphoric acid is linear from 3 p g / L , the detection limit, to 120 mg/L, the highest concentration tested. Metal ions depress phosphorus emission and must be removed by cation exchange. Concentrations of sulfur greater than 5 mg/L interfere positively. Volatile phosphorus compounds produce a larger signal than nonvolatile compounds. Krawczyk and Allen (12F) studied the adsorption of orthophosphate on borosilicate, citrate of magnesia, polyethylene, and polyvinyl bottles in both a distilled water and seawater matrix. There are no problems with glass bottles at low orthophosphate concentrations in distilled water up to 7 days, but they must first be acid washed. In seawater, losses of orthophosphate were noted after 16 days in polyethylene. If mercuric chloride is added, the bottles can be used without any pretreatment. Polyvinyl bottles can be used for seawater samples as received from the supplier. Tillman and Syers (22F) reported that mercury causes a significant positive interference in the molybdate blue colorimetric determination of low levels of inorganic phosphate. The interference results from the formation of a precipitate that varies in particle size and is not always visible to the naked eye. At higher levels of phosphate, a coarse precipitate forms that partially removes the molybdophosphate complex from solution. The mercury interference is eliminated by the formation of a complex that results from the addition of chloride or a metabisulfite-thiosulfate reagent. Problems associated with the determination of phosphorus compounds in water are discussed by Burton (4F). Spielholtz, Toralballa, and Willsen (20F)determined boron in seawater by atomic absorption spectrometry. The sample is concentrated by boiling to 25% of the original volume and then is extracted with 2-ethyl-1,3-hexanediol in methyl isobutyl ketone. A semiautomated method for the determination of boron in surface water by atomic emission spectrometry is described by Pierce and Brown (17F).The technique employs a nonmechanical concentration step, an automated boron concentration by methanol distillation, and an automated aspiration-analysis procedure. Sixty specimens can be distilled
and 180 distilled specimens can be analyzed per hour. The detection limit and sensitivity are 0.002 and 0.004 mg/L, respectively. An improved curcumin method for the determination of 0.25 to 1.00 mg/L of boron in water is presented by Goldman, Taormina, and Castillo (7F).The modified method eliminates interferences and the evaporation step of the standard method. The sample is acidified with hydrochloric acid and boron is extracted with 2-ethyl-1,3-hexanediol in chloroform. The boron in the organic phase is converted to the absorbing rosocyanine red complex by using a solution of curcumin in glacial acetic acid followed by the addition of sulfuric acid. The sample is then diluted with 95% ethanol, and the absorbance read at 550 nm. A simplified automated curcumin method for the determination of boron in seawater is described by Ostling (16F). The system is a single-channel, discrete type. Flow diagrams are given. Bull, Evans, and Foy (38’) modified an automatic alkaline carminic acid method for the determination of boric acid in water. Interference from precipitation of dissolved metal ions such as lead, iron, and aluminum can be prevented by the addition of the disodium salt of EDTA. Isozaki (11F) described a spectrophotometric method for determining microamounts (0.02 pg) of boric acid and tetrafluoroborate ion in water. The tetrafluoroborate ion is chelated with methylene blue and extracted with dichloroethane and its absorbance measured a t 660 nm. The boric acid is then converted to the tetrafluoroborate ion in acid solution using hydrofluoric acid and treated as above. Automated methods for the determination of silicate in natural water are described by Truesdale and Smith (23F). The methods involve the formation of a- and P-molybdosilicic acids a t pH 4.0 and 1.8,respectively. The a- and @-acidsare then reduced by nickel chloride and determined a t 660 and 740, and 660 and 790 nm, respectively. Phosphate interference is eliminated by addition of oxalic acid. The analytical curve is linear from 0 to 1.0 mg/L. Suzanne, Vittori, and Porthault (21F) used alternatingcurrent polarography and impulse polarography to determine silicon in water over the range of 10 to 100 pg/L. The sample is acidified with sulfuric acid and then ammonium molybdate is added. After standing, the molybdosilicic acid is extracted with ethyl acetate. An equal volume of ethanol is added; the mixture is buffered to a pH of 1.98 before it placed in the polarographic cell and analyzed.
SELENIUM, ARSENIC, ANTIMONY, AND TELLURIUM Several hydride generation methods have been reported for the determination of arsenic, selenium, antimony, and tellurium in water and seawater. Measurement is made by either atomic absorption or atomic fluorescence. King and Morrow ( 4 G )used sodium borohydride to form arsine and selenium hydride and then passed the gases into a low-temperature argon/air/hydrogen flame for measurement by atomic absorption. Background correction is made by adjusting the gas flow rates. They reported a limit of detection of 5 pg/L for arsenic and 1pg/L for selenium. Thompson (13G)described an atomic fluorescence method for determining antimony, arsenic, selenium, and tellurium using sodium borohydride for hydride generation. Atomic fluorescence was excited using modulated microwave sources and detected by a dispersive measuring system. An automated method is described by Pierce et al. (8G)for the determination of submicrogram levels of arsenic and selenium. The hydrides are produced in an automated system and passed to a tube furnace mounted in the light path of an atomic absorption s ectrometer. They reported that 70 samples per hour could e! analyzed with a limit of detection of 0.011 pg/L for arsenic and 0.019 p g / L for selenium. Using the same system, Pierce and Brown ( 7 G ) investigated inorganic interferences. The study showed a significant suppressive effect upon the determination of arsenic and selenium by several cations and anions. The study also showed an interference dependence upon the order of reagent addition in the automated technique. A loss of arsenic and selenium caused by the sample cup composition material is also noted. ANALYTICAL CHEMISTRY, VOL. 49, NO. 5, APRIL 1977
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Flameless atomic absorption spectrometric techniques have been reported by many investigators for arsenic, antimony, and selenium. Martin, Kopp, and Ediger (5G) developed a flameless method for the determination of selenium in fresh water, waste water, sediment, and sludge. The samples are first digested with nitric acid and hydrogen peroxide. Nickel nitrate is then added to both the standards and samples to prevent loss of selenium by volatilization during the charring step. The detection limit is 0.2 pg/L without the use of scale expansion. To determine selenium in water and industrial effluents, Henn ( 2 G )first treated the samples with a cation exchange resin to eliminate interference from cations and then added a molybdenum solution to enhance sensitivity and to suppress interference from inorganic anions. The range of the test is 1-50 pg/L of selenium. Yasuda and Kakiyama (14G) determined arsenic and antimony in river and industrial waste waters by the flameless technique without any sample treatment. They reported that only phosphate interferes with the determination, and that results agreed with those obtained by conventional colorimetric methods. Kamada, Kumamaru, and Yamamoto (3G)also described a flameless technique for determining arsenic, antimony, and selenium in water. The absorbance of selenium is affected by nitric, sulfuric, and hydrochloric acids. An indirect flameless method for determining picogram amounts of arsenic and phosphorus in pure water is discussed by Rozenblum ( I I G ) .The method involves the conversion of arsenic and phosphorus into the yellow 12-molybdoarsenate or phosphate, extraction into butyl acetate, decomposition of the heterpoly compounds with aqueous ammonium, and the back-extraction of the liberated molybdenum into aqueous solution. The molybdenum is then determined by flameless atomic absorption spectrometry. Mesman and Thomas (6G) determined selenium and arsenic in water by both flame and flameless atomic absorption spectrometry. Each technique was analyzed for requirements in speed of determination, sample size, potential interferences, coefficients of variation, and overall ease in use. Pradzynski, Henry, and Stewart (9G)used coprecipitation and energy dispersive x-ray fluorescence spectroscopy to determine 0.6-50 ppb of selenium in fresh waters in the presence of transition elements. They stated that the relative speed and economy make the method suitable for application in environmental monitoring. Coprecipitation with molybdenum sulfide in 2 M hydrochloric acid was proposed by Reay (IOG)for the recovery of microgram amounts of arsenic from natural waters. After dissolution of the sulfide precipitate, arsenic is determined photometrically by a molybdenum blue method. Overall recovery of arsenic is 99%. An extraction-photometric method for the determination of antimony in seawater using diantipyrylmethane was reported by Afanas’ev et al. ( I G ) .In the presence of ascorbic acid and potassium iodide, a colored complex SbI4- diantipyrylmethane is formed. The relative standard deviation is 2-5% in the range of 1.5 to 5.2 wg/L. Shendrikar and West (12G) investigated rates of loss of selenium from aqueous solution stored in various containers. The adsorption losses of 1 ppm selenium in Pyrex beakers after 15 days at pH 7,3.8, and in nitric acid were 4,1.5, and 1%, respectively. In flint glass beakers, losses of about 5,2.5, and 1.5% occurred a t pH values of 7, 3.8, and in nitric acid, respectively. Losses in polyethylene beakers were greater than 8, 3 and 2%, at pH 7, 3.8, and in nitric acid, respectively.
HALIDES The use of a solid state chloride ion-selective electrode, based on HgS/Hg&12, was studied by Sekerka, Lechner, and Wales ( I 9 H ) for manual and automated measurements of chloride in natural, industrial, and waste water. The electrode displays Nernstian response for 0.05-3.50 ppm chloride. An ion-selective chloride electrode with a low impedance and portable shock-proof voltmeter was used by Van Oort et al. (25H)for field measurements of the chloride activity in water. Interferences by substances forming complexes with silver were eliminated by adding a few drops acetic acid to the sample solution. Nazarova, Stradomskii, and Bykadorova ( I 6 H ) reported on the use of ion-selective electrodes for the 146R
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automatic monitoring of chloride in natural waters. Dissolved salts in the water interfere because of the change in the ionic strength. Torrance (22H) used a Ag/AgCl wire electrode vs. a HgzS04 reference electrode to determine chloride in boiler water in the range of 0.1 to 10 pg/mL of chloride. Stainton (2OH) described an automated method for the determination of chloride in water using cation exchange and measurement of electrical conductance. Chloride and sulfate are converted to their free acids by hydrogen ion exchange. Silver-saturated exchange resin is used to precipitate chloride and distinguish it from sulfate. Bromide and iodide give positive interferences with chloride. Takata (2123 used liquid chromatography equipped with a closed sample feeder and with an anion exchanger to concentrate traces of chloride in water. The chloride is then determined coulometrically. Nagy, Toth, and Pungor (15H) determined chloride in streaming water samples by a programmed coulometric technique. Silver ion is generated coulometrically in situ and the change in the chloride ion activity is followed with a chloride ion-selective membrane electrode downstream. The silver ion is generated by an electrical current that is increased or decreased linearly with time. An automated, chromotropic colorimetric method was developed by Afghan et al. ( I H )for determining 0.25-100 mg/L of chloride. Chloride catalyzes the conversion of nitrate to nitrite and the resultant nitrite reacts with chromatropic acid to form a colored species that is measured at 505 nm. Twenty samples per hour can be analyzed. Afghan and Ryan ( 2 H )also recommended that the chromotropic reagent be free of chloride impurity in order to obtain reproducible and accurate results. They reported that the reagent supplied by different manufacturers contained varying amounts of chloride. Ramirez-Munoz ( I 7 H ) described an automated discretesample method for the turbidimetric determination of chloride between 5 and 250 ppm in water. Chloride is precipitated with silver ions and the turbidity of the silver chloride suspension is measured at 600 nm. An x-ray fluorescence spectrochemical method for the determination of chloride in water is reported by Magyar and Kaufmann ( 1 3 H ) . Chloride is first concentrated by coprecipitation from 100 mL of sample by using silver thiocyanate. Standards are prepared in the same manner. Reproducibility of 3%was obtained. Vis and Verheul (26H) used alpha-particle activation to determine chloride in natural water. The limit of detection is 0.4 ppm; reproducibility is 5%. Millero, Schrager, and Hansen (14H)determined total sulfate, chlorinity, and total alkalinity in seawater by thermometric titration. The precision for chlorinity is 0.04%. A statistical comparison of six methods for determining fluoride in surface waters was reported by Boniface et al. (7H). The methods compared were colorimetric, titrimetric, fluorometric, and ionometric. The accuracy and precision were estimated using standard solutions. Before establishing the most suitable method, they also took into account the possible presence of interfering ions. An automated fluoride method that uses AutoAnalyzer modules in conjunction with a fluoride ion-selective electrode was evaluated by Erdmann ( 9 H ) . With 38 natural water samples containing 0.04-7.75 mg/L of fluoride, the average difference between the values obtained by this method and a similar manual method was 0.026 mg/L. Aluminum concentrations above 2 mg/L interfere. Thirty samples can be analyzed per hour. Franke (IOH)determined fluoride in polluted water by both an ion-selective electrode method and an alizarin-complexon-lanthanum complex method. In the latter method, fluoride is first distilled. The variation coefficients of the two methods were 13.2 and 1.7%, respectively. Banerjee (3H, 4 H ) described both laboratory and field volumetric methods using 4,5-dihydroxy-3-[(p-sulfophenyl)azo]-2,7-naphthalenedisulfonicacid (SPADNS)-thorium lake to determine fluoride in water. In the laboratory method, the samples are preconcentrated; then, to avoid interference, chloride is removed by addition of silver sulfate, and fluoride separated as HzSiFG by steam distillation. Das et al. ( 8 H )determined fluoride in tap water after substoichiometric extraction with trimethylchlorosilane into benzene. An isotope dilution method usin a carrier-free spike of fluoride-18 was used. Less than 1 m g k of fluoride can be
determined. A rapid method for the radiometric determination of fluoride in surface water samples is described by Van der Mark and Das (2414). The method depends on the chemisorption of hydrofluoric acid on a glass absorber from a dilute acid solution, which has been spiked with fluoride-18. The limit of detection is 0.03 wg/mL. For the determination of fluoride in seawater with a selective ion electrode, Rix, Bond, and Smith (18H)used a modified method of standard addition to provide a direct and simple determination without the need for buffers and/or complex calibration procedures. The effect of the valency states of iodine on the accuracy and reproducibility of determining iodide when using an iodide selective-electrode was studied by Zeinalova, Morshina, and Senyavin (28H). Elemental iodine interferes with the iodide determination if the ratio of iodine to iodide is greater than 10. The effect of iodate is insignificant. A procedure is suggested for iodide and total iodine determinations in natural waters. Lambert, Hatch, and Mosier (12H) spectrophotometrically determined IO-, iodine, and iodide in water in the range of 2.5 to 40 ppb. The sample is treated with N-chlorosuccinimide to convert all iodide and free iodine to IO-. Leuco crystal violet is then added and is oxidized to the colored form by IO-. An interference study was made. Nitrate greater than 40 ppb, cyanide greater than 10 ppb, sulfide greater than 100 ppb, and phenol greater than 50 ppb interfere. Interference from less than 2 ppm nitrite can be prevented by the reaction with N-chlorosuccinimide. Wong and Brewer (27H) described a neutron-activation procedure for determining iodide in seawater. Iodide is separated from most other anions by strongly basic anion exchange resin. The iodide is eluted with 2 M sodium nitrate and concentrated by precipitation as palladium iodide in the presence of excess palladium(I1) with elemental palladium as carrier. The precipitate is pressed into a pellet for analysis. A technique for the determination of trace amounts of halides in various type waters by the combination of a Ag/AgCl potentiometric sensor following separation by liquid chromatography on an ion-exchange resin in the metal form was proposed by Franks and Pullen (11H). The determination of chloride, bromide, and iodide in drinking waters by molecular emission cavity analysis was described by Belcher et al. ( 5 H ) . The method is based on measuring the emissions of the chloride, bromide, and iodide indium salts at 360, 376, and 410 nm, respectively. The detection limits are 0.5 ppm for chloride and bromide and 10 ppm for iodide. A method for the continuous monitoring of chloride between 3.5 mg and 35 g/L and fluoride between 18.9 kg and 18.9 g/L in surface and underground waters by ion-selective electrodes was investigated by Berthier ( 6 H ) . Fluorides, chlorides, and iodides were determined by Zeinalova and Senyavin (29H) in natural waters by using a membrane selective electrode a t pH 5-9 for chloride and fluoride and a t pH 1-12 for iodide. The effect of acetate and citrate ions on the buffer solution is eliminated by the addition of a 0.005 M lanthanum salt. Other interferences are also discussed.
SULFATE, SULFIDE, AND SULFUR Lambert and Ramasamy (95)determined sulfate in water by displacement of violurate anion from barium violurate a t pH 6.0-6.2. The violurate anion is measured spectrophotometrically a t 520 nm. Interfering cations are removed by ion exchange. Adamski and Villard (15)compared the gravimetric method and the automated spectrophotometric methylthymol blue method for determining 0-200 mg/L of sulfate in water and waste water. Both methods produced practically identical results. Cation interferences are removed by ion exchange. Sulfide, sulfite, phosphate, and tannic acid interfere but only a t levels much above those usually encountered in waters. An automated method for the determination of chloride and sulfate in fresh water using cation exchange and measurement by electrical conductance is described by Stainton (155).Ion
exchange is used to convert chloride and sulfate salts to their free acids that are then measured by electrical conductance. The use of silver-saturated exchange resin to precipitate chloride permits the measurement of sulfate. High levels of nitrate, phosphate, and fluoride give positive interference for sulfate. Sawin et al. (145)examined the selectivity of the titrimetric determination of sulfate a t pH 2 and 4 using the metal indicators Orthanilic K and Orthanilic S. A method using Orthanilic K is presented for determining sulfate in water and other materials. An indirect method for the determination of sulfate in water by atomic absorption was proposed by Galle and Hathaway (65). Natural alkaline earth-bicarbonate waters having p H values between 7.2 and 8.0 are mixed with a barium solution, allowed to stand, and the excess barium is determined at 553.5 nm. An x-ray fluorescence spectrochemical method for the determination of sulfate in water was reported by Magyar and Kaufmann (115).Sulfate is quantitatively coprecipitated from solution with barium chloride and the sulfate in the precipitate determined by x-ray fluorescence. Standards are prepared in a like manner. The method enables sulfate to be determined in a 50-100 mL sample with a reproducibility of 3%. Luther and Meyerson (105) measured sulfate in seawater by adding a standard solution of lead nitrate in excess to the sample and measuring the amount of lead ion remaining in solution polarographically. Millero, Schrager, and Hansen (125) determined total sulfate in seawater by thermometric titration. The precision of the analysis for sulfate is 0.3%. X-ray fluorescence spectrometry was used by Gallo, Taylor, and Zeitlin (75)to determine sulfur concentrations in aqueous mixtures resembling seawater. Sample pretreatment and handling were minimized by the x-ray method. Results were compared to those obtained by gravimetric analysis. A method for the separation of thiosulfate and polythionates by high-speed anion-exchange chromatography is given Detection of these anions a t 0.3 by Wolkoff and Larose (165). ppm in mining waste water and environmental samples is possible with a cerium(1V)-fluorescence detection system. De Groot, Greve, and Maes (55)determined sulfur in organic compounds in surface water samples coulometrically after an oxidative destruction of the sample in a quartz tube to produce sulfur dioxide. The products are swept into a titration cell containing a platinum indicator electrode, a platinum generator electrode, and a generator electrode containing known amounts of 13- and I-. The sulfur dioxide is oxidized to sulfate and 13- is detected by the platinum indicator electrode. Cassidy ( 4 5 ) reported that elemental sulfur exhibits a pronounced reversed-phase effect on styrene-divinylbenzene packings and this selective interaction can be used for the determination of sulfur in water by high-speed liquid chromatography. Absorption at 254 nm offers sensitive detection (1-10 ng) and calibration curves are linear up to 10-20 kg. The direct potentiometric determination of sulfides in seawater with a sulfide-selective membrane electrode was proposed by Mor et al. (135).The experimental evaluation of the apparent mixed dissociation constants and the thermodynamic activity coefficient in spiked seawater samples, by means of the electrode, permitted direct calibration in terms of activity. It is also possible to establish an experimental equation for the correction of the electrode potentials in terms of pH that allows direct calibration of the electrodes in terms of total sulfide concentration. Baumann (25) determined ppb levels of sulfide in water with a sulfide-selective electrode after concentration of the sulfide. Zinc acetate and sodium carbonate are added in sequence to coprecipitate the zinc sulfide with zinc hydroxide. Hoover (85)used a new gas-sensing electrode to determine molecular hydrogen sulfide at concentrations greater than 0.1 mg/L. The electrode consists of semipermeable membranes, buffered electrolyte filling solution, silver sulfide crystal sensor, and lanthanum fluoride internal reference electrode. Canterford (35)reported that a rapid (short controlled drop time) dc polarographic method provides a simple method for simultaneous cyanide-sulfide determination. The detection limit for sulfide is 4 X 10-6 M. ANALYTICAL CHEMISTRY, VOL. 49, NO. 5, APRIL 1977
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the relative standard deviations for determinations of 0.5 and 5 mg/L of nitrite are 1.5 and 2.3%, respectively. A list of interfering constituents is included. Garg, Mehta, and Katyal (11K) determined nitrite in well water by reacting it with sulfanilic acid and various pyridinols. The detection limit for Peterson, Metro, and Hopke (28K)modified the method nitrite is 20 pg/L using 2-amino-3-pyridinol and 10 pg/L with of Lambert and DuBois to determine nitrate in fresh water. 2,3-pyridinol and 2-chloro-3-pyridinediol. Fe(III), Cu(II), Excellent results were obtained over the range of 10 to 5000 Zn(II), Cd(II), Hg(II), Co(II), and Ni(I1) interfere. pg/L. Several aromatic, ortho diamines were considered by Evans and Partridge (20K)used an ion-selective electrode Canney ( 5 K )for determining nitrites and nitrates in natural to determine ammonia in water and waste water. EDTA is waters by either spectrophotometric or fluorometric proceadded to prevent the precipitation of hydroxides. Precision dures. The monopiazselenol of 3,3’-diaminobenzidine and is 4% for ammonia (as N) concentrations greater than 0.4 mg/L. 2,3-diaminofluorene were selected as the two most promising and 0.015 mg/L for concentrations less than 0.4 mg/L. A liqreagents. An increase in sensitivity is achieved by using an uid-membrane ammonium electrode and a gas-detecting extraction step with 1,2-dichloroethane. High levels of organic ammonia electrode were used by Dewolfs et al. ( 8 K ) to dematter interfere. A similar study was conducted by Cantermine nitrate and ammonia in canal water. The response ney, Armstrong, and Wiersma (6K).Of the reagents evalutime and stability of both electrodes is comparable although ated, 2,3-diaminofluorene (2,3-DAF) and 5-(3,4-diaminothe detection limit is approximately 50 times lower for the phenyl)-2,1,3-benzoselenadiazole(DABSe) were selected for ammonia electrode. A concentration of 20 ppb can be deteranalytical use. Detection limits are 1.5 and 1.0 pg/L of nitrite mined by this electrode. (as N) for the 2,3-DAF and DABSe procedures, respectively. A modified oxidation-diazotization spectrophotometric If nitrate is determined, it is initially reduced to nitrite by a method is given by Matsunaga and Nishimura (21K)for the Cd-Hg column in both of the above aromatic ortho diamine determination of submicrogram quantities of ammonia in procedures. The optimum conditions for the reduction of nifresh and seawaters. Relative standard deviations for five trate to nitrite by cadmium are discussed by Nydahl (27K). replicate determinations is approximately 4% at the 0.5-118 Maly and Fadrus (20K)determined nitrate in a sulfuric acid level and 2% at the 2-gg level. Liddicoat, Tibbitts, and Butler medium with an excess of indigo carmine. The unreacted in(19K)determined ammonia in seawater by a modified phenol digo carmine is titrated with potassium permanganate. An hypochlorite procedure. Sodium dichloroisocyanurate was automated method proposed by Afghan and Ryan ( 2 K )utiused as the hypochlorite donator and potassium ferrocyanide as a senlizes 2,2’-dihydroxy-4,4’-dimethoxybenzophenone was substituted for the nitroprusside catalyst. Beer’s law is sitive fluorimetric reagent for the determination of nitrate in obeyed over the concentration range of 0- to 20-pg atoms per a wide variety of natural waters and sediments. A procedure liter of ammonia (as N). Gravitz and Gleye ( 1 4 K )found that to eliminate possible interferences from high concentrations sunlight exposure of the reaction mixture for the phenolof chloride, sulfide, and humic acid substances is also incorhypochlorite determination of ammonia results in the forporated. Twenty samples per hour can be analyzed, and conmation of a compound that absorbs at 640 nm. Protection of centrations as low as 5 Wg/L of nitrate (as N) can be detectthe reaction mixture from strong light results in low reagent ed. blanks and ammonia standards that display a Beer’s law deThe adaptation of an ultraviolet technique to an automated pendence on concentration. discrete-sample system is described by Ramirez-Munoz (29K) Sekerka and Lechner (31K)described a procedure that sifor the determination of nitrate. The material required and multaneously determines ammonium, sodium, and potassium the operating conditions are discussed. Sixty samples per hour ions in natural and waste water samples by use of ion-selective can be analyzed with excellent reproducibility. Dilutions of electrodes. The results are printed out as concentration units up to a 1200:l ratio were made by Goulden and Kakar (13K) directly from an automated continuous-flow system with an on-line minicomputer and printer. Twenty samples per hour on the AutoAnalyzer when determining nitrate levels in water are analyzed. For samples with ammonium, sodium, and poover the ranges of 2 pg/L to 250 mg/L of nitrate (as N). The determination of nitrate a t the ppb level in environmental tassium concentrations greater than 10 ppm, the ammonium detection limit is 0.1 ppm. The standard deviation values are samples with a continuous flow immobilized enzyme reaction generally less than 10% of the concentration value. is described by Senn and Carr (32K).Nitrate is reduced to nitrite by the radical cation of l,l’-dimethyl-4,4’-bipyridinium An evaluation study of some of the current techniques for dichloride in the presence of the enzyme nitrate reductase. determining nitrogen compounds in water was conducted by The resulting nitrite is then determined by an azo dye reacAstrani (3K).The analytical techniques considered were the Kjeldahl method for determining organic nitrogen; the titrition. Sample concentrations in the range of 17 ppb to 7 ppm of nitrate can be measured. A precision of 1%was obtained at metric and direct nesslerization methods for determining ammonia; the brucine, ultraviolet spectrophotometric, ionthe 0.2-ppm level. Youne et al. ( 3 7 K ) described a sirnt.de Dortable Dolaroselective electrode, and automated hydrazine reduction graphic kalyzer for determination of niirate in natural water methods for nitrate; and the total nitrogen analyzer method samples. The polarographic waves were determined in the for total nitrogen and, if possible, for the determination of organic nitrogen, ammonia, and nitrate as well. presence of either Zr(1V) or U(V1). The use of these catalytic Hansen, Ruzicka, and Larsen (15K) determined total insystems allows direct compensation of background currents organic nitrogen in aqueous solutions by first reducing the due to interferences. Two ion-selective electrodes were used by Weiss (36K)to inorganic nitrogen compounds to ammonia with Devarda alloy and then measuring the concentration of ammonia by the determine nitrate in drinking and industrialized waters. Silver hydroxide is added to minimize the effect of interfering ions. air-gap electrode. Organic nitrogen-containing compounds The detection limit is 0.6 mg/L of nitrate in weakly mineraldo not interfere. Approximately 6 min is required to analyze ized waters and 5 mg/L in strongly mineralized waters. Mera 100-pL sample. The standard deviation is less than 3%. A tens, Van den Winkel, and Massart (23K) described manual procedure for determining ammonia, nitrate, and organic nitrogen in water and waste water with an ammonia gasand automated procedures for determining nitrates in water sensing electrode is discussed by McKenzie and Young (22K). with an ammonia ion-selective electrode. The nitrates are Nitrate is reduced to ammonium ion by addition of Devarda determined by measuring the ammonia produced during a alloy. Ammonia is distilled from a sample aliquot and the reheterogeneous reduction using Devarda alloy. The concenmaining nitrogen-containing organic compounds are then trations found for samples containing 2 and 20 ppm were 1.95-2.0 and 19.8-20.3 ppm, respectively. This method, which degraded to ammonium ion by a Kjeldahl digestion procedure. Interferences by magnesium and other metals forming incan also be applied to mineral waters and sewage, contains proposals for the elimination of excess ammonium and nisoluble hydroxides are prevented by the addition of EDTA. Scheiner (30K) used an indophenol method to determine trite. A spectrophotometric method for the determination of ammonia and Kjeldahl nitrogen in domestic waste waters in nitrite is presented by Dougherty and Laban ( 9 K ) . Nitrite concentrations of 0.02 to 1mg/L of ammonia (as N). Magnereacts with 4,4’-bis(dimethy1amino)thiobenzophenone and sium, calcium, copper, amino acids, nitrite, and mercury may the resulting colored species is extracted into chloroform for interfere. The use of an ammonia probe for the determination of total nitrogen in river and seawater is also described by absorbance measurement a t 650 nm. Beer’s law is obeyed.and NITRATE] NITRITE, AMMONIA, ORGANIC NITROGEN, CYANIDE] CYANATE, A N D THIOCYANATE
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Mertens, Van den Winkel, and Massart (24K).The distillation procedure is avoided by determining ammonia directly in the diluted digestion mixture. A comparison of digestion procedures is included. This procedure allows good precision and accuracy with a limit for precise measurements of approximately 5 ppm nitrogen. A persulfate digestion coupled with an automated indophenol colorimetric procedure was used by Adamski ( I K )to determine Kjeldahl nitrogen in seawater. The detection limit is 0.06 mg/L for the operating range of 0 to 5.6 mg/L. Stevens (34K) used a commercially available ammonia probe in an automated flow-through system to determine ammonia concentrations in Kjeldahl digests of fresh waters. In the 0.1-1.0 mg/L range of nitrogen, 10 samples per hour can be analyzed. A single acid-hydrogen peroxide digestion procedure for determining Kjeldahl nitrogen and total phosphorus in natural waters is presented by Nicholls (25K).A phenol-hypochlorite colorimetric step follows the digestion. Concentrations as low as 20 pg/L as nitrogen can be determined reproducibly. The analysis rate is 30-40 samples per day. Sharp (33K) outlined a procedure for simultaneously determining particulate organic carbon and nitrogen in seawater with a modified CHN analyzer. With appropriate blank controls, the practical lower detection limits are about 5 pg carbon and 1 pg nitrogen. The effects of water volume filtered and the number of filters used on the observed concentrations of particulate nitrogen and carbon in marine waters were examined by Gordon and Sutcliffe (12K)using 47-mm, 0.8-pm silver filters. It was concluded that the best procedure is to filter through single filters using gravity when possible. The optimum volume for filtering depends on the concentration of particulate matter and generally is between 1 and 10 liters. Direct-current polarography was used by Canterford (7K) to simultaneously determine cyanide and sulfide. The optimum supporting electrolyte p H is in the range 9-10, The cyanide detection limit is 5 X 10+ M. Tanaka and Odo (35K) described a spectrophotometric method for determining cyanide. Hg(II)-bis(4-sulfobenzyl)dithiocarbamic acid (BSDTC) complex reacts with cyanide in the presence of Cu(I1)-NTA complex to yield a brown Cu(I1)-BSDTC complex. Cyanide is determined from the absorbance of the Cu(I1)-BSDTC complex at 433 nm. Beer's law is obeyed for cyanide concentrations less than 0.5 ppm. Interferences from sulfide, thiosulfate, and iodide were eliminated by distillation after oxidation with potassium permanganate. A spectrophotometric method for determining cyanide by destroying the platinum-3,4-diaminobenzoicacid complex was discussed by Keil (18K).Cyanide in amounts of 0 to 30 pg in water was determined using 3,4-diaminobenzoic acid as the complexing agent a t pH 3.9 f 0.1 in the presence of platinum/nickel/ferric chlorides as reaction accelerating aids. The maximum permissible levels of interfering anions and cations are listed. A spectrofluorometric procedure for determining free and complexed cyanide in water is presented by Brebec et al. ( 4 K ) .Cyanide catalyzes the air oxidation of pyridoxal to pyridoxylacetone, which is very fluorescent. The rate is proportional to the cyanide concentration. Amounts greater than 1 ppb can be determined with a reproducibility of f5%. The continuous determination of free cyanide in effluents using a silver ion-selective electrode is discussed by Hofton (16K).The lowest practical limit of detection is 0.01 pg/mL of cyanide. Ishii, Iwamoto, and Yamanishi ( 17 K ) colorimetrically determined cyanate with hydroxylamine-diacetyl monoxime. Cyanate reacts with hydroxylamine at 60 "C to form hydroxyurea, which reacts with diacetyl monoxime in the presence of acidic catalyst at 100 "C to produce a red color whose absorbance is measured at 520 nm. No interference was found from chloride, ammonium ion, or amines. Nota (26K)used a cyanide ion-selective electrode for determining 1-100 ppm thiocyanate in water in the presence of bromide, chloride, ammonia, thiosulfate, cyanide, iodide, and sulfide. The sample is treated with bromine in water to convert thiocyanate to cyanide, excess bromine is removed by treatment with phenol, and BrCN is treated with SOz-saturated water to give cyanide. Thiocyanate is then calculated by difference between the cyanide concentration after oxidation and the original cyanide concentration. Cations are originally removed by a cation-exchange resin.
ALKALINITY, CARBON DIOXIDE, A N D pH Millero, Schrager, and Hansen ( 3 L ) determined total sulfate, chlorinity, and total alkalinity in seawater by thermometric titration. The precision is 0.1% for total alkalinity. A photometric probe that uses optoelectronic components, including light-emitting diodes, was studied by Anfalt, Graneli, and Strandberg (1L)for the determination of total alkalinity in seawater. Influence from ambient light is considerably reduced. Good agreement was obtained between the photometric method using methyl red indicator and the potentiometric procedure. Kegel ( 2 L )outlined a procedure for the quantitative determination of carbon dioxide in natural water. The sample is placed in a gas-tight apparatus with carbon dioxide-free distilled water in such a way that gas exchange between the two waters is possible. After equilibrium has been achieved, the carbon dioxide content of the distilled water is determined and is a measure of the carbon dioxide content of the natural water. A high-sensitivity carbon dioxide analyzer is described by Scarano and Calcagno (415).This procedure is based on permeation of a small quantity of carbon dioxide through a Teflon tube into a flowing solution. The concentration of carbon dioxide is determined from the change in pH of the 0.1 M sodium bicarbonate M potassium chloride and 1 X flowing solution. Free carbon dioxide, bicarbonate, carbonate, and hydroxide were determined in synthetic samples and in to tap water samples in the concentration range of 5 X 2 X 10-3 M. Precision and accuracy are good. OXYGEN A N D OTHER GASES Kollig, Falco, and Stancil(4M) discussed the determination of dissolved oxygen, nitrogen, and carbon dioxide in water by diffusion and gas chromatographic techniques. A stream of helium carries the gases, which are diffused through a plastic membrane, to a dual column-gas chromatographic-trace gas analyzer equipped with helium ionization detectors. The system has a sensitivity of 5 to 10 pg/L dissolved gases. A spectrophotometric method for determining dissolved oxygen in water is presented by Poe and Diehl(9M).Tris(4,7dihydroxy-1,lO-phenanthroline)iron(II)reacts rapidly and quantitatively with dissolved oxygen in alkaline aqueous solution. In ammoniacal solution, the reaction is accompanied by the disapfiearance of the intense red color of the iron(I1) compound. A pale-gray iron(II1) complex is produced by this reaction. By measurement of the absorbance of a solution containing the ferrous compound before and after the injection of an oxygen-containing solution, the concentration of dissolved oxygen in the sample can be accurately determined in the range of 1 to 20 ppm. Karlsson and Torstensson ( 3 M ) determined the oxygen content of air-saturated distilled water between 10 and 40 "C by use of a controlled-potential coulometric method based on the Tortensson method for the iodometric determination of nitrite. The maximum error for the determination is f0.3%, and the time of analysis is 3 min. An analyzer for measuring ozone concentrations in water by a chemiluminescence procedure is described by Stepanova et al. (11M).The accuracy is f5%. The sensitivity of the ozone determination is 30-fold higher than that of chlorine. A review with nine references was compiled by Palin ( 8 M )on the current diethyl-p-phenlenediamine methods for residual halogen compounds and ozone in water. Whitfield (12M) reviewed three colorimetric procedures for determining free chlorine in water. The syringaldazine method was found to be the best for measuring low levels of free chlorine. The syringaldazine procedure was modified by Meier, Cooper, and Sorber ( 6 M )to produce a test for the determination of free available chlorine that is accurate, precise, and free of common interferences. Five commercially available test kits for determining free chlorine residuals in aqueous solutions were evaluated by Cooper et al. (1M).Variations of the neutral orthotolidine test as well as the syringaldazine, N,N-diethyl-p -phenylenediamine, and modified o -tolidinearsenite tests were considered. A syringaldazine method for determining free available chlorine in water is described by Cooper, Sorber, and Meier (2M).The absorbance is measured a t 530 nm. Morrow and Roop (7M)discussed the determination of free and total chlorine residuals by use of an amperometric analyzer operated at specific electrode potentials with appropriate ANALYTICAL CHEMISTRY, VOL. 49, NO. 5, APRIL 1977
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reagents. An amperometric method for measuring residual chlorine levels in cooling water is presented by Manabe ( 5 M ) . Sodium pyrophosphate is added to remove heavy metal interference. Two samplers for monitoring dissolved gases in lake water and sediment were described by Rudd and Hamilton (IOM). An in situ vertical point sampler was used over several months to obtain dissolved gas samples from precise and reproducible points in the water column of a stratified lake. A sediment gas sampler that monitors concentrations by equilibration of dissolved pore water gases with water inside plastic tubing is also discussed. Construction and operation are relatively simple.
OXYGEN DEMAND AND TOTAL CARBON A micro semiautomated procedure for the determination of chemical oxygen demand in surface and waste waters is described by Jirka and Carter ( 7 N ) .The appearance of trivalent chromium is measured spectrophotometrically at 600 nm after sample digestion. Concentrations of 3 to 900 mg/L can be determined. This method is compared to the standard procedure with respect to precision, accuracy, ease of analysis, and comparability of data. The ASTM-D1252-67 method for determining COD of waste water was slightly modified by Wolff (13N)to minimize loss of volatile organic compounds. Details of the procedure and a comparison of COD results from 12 compounds for the ASTM and modified procedures are included. A simplified acid dichromate digestion was used by Canelli, Mitchell, and Pause ( 2 N )to determine chemical oxygen demand in water and waste water samples containing l o ppm) in water was pyrolyzed, oxidized to carbon dioxide, and the carbon dioxide was absorbed in sodium hydroxide solution. After acidification with hydrochloric acid, the potential of this solution is measured. Analysis time is 8 min with a relative error of lt20%. An air-gap electrode was used by Fiedler, Hansen, and Ruzicka ( 3 N )to determine total inorganic and total organic carbon in waste and lake waters. The total inorganic carbon is determined after wet chemical oxidation of the sample with potassium persulfate. The resulting total carbonate content can be determined directly if the concentration exceeds 2 mM. For samples containing less than 0.1 mM carbonate, a preconcentration steo is used. The relative standard deviation is less than 3%. Modifications to a CHN analyzer are described by Sharp ( I I N )for the determination of Darticulate organic carbon and nitrogen from seawater. Partiiulate organic carbon and nitrogen on 24-mm GFC filters can be determined simultaneously. With appropriate blank controls, the practical lower limits for analysis are 5 pg of carbon and 1pg of nitrogen. An automated procedure for determining dissolved organic carbon in lake water is presented by Goulden and Brooksbank (6N).The inorganic carbonate is removed in a heated, packed column; the organic carbon is oxidized; and the resulting carbon dioxide measured by an infrared analyzer. Two alternate oxidation methods are used ultraviolet irradiation and silver-catalyzed peroxydisulfate at 95 "C. The silver-catalyzed peroxydisulfate method is more convenient and precise but does not completely oxidize all materials in water. The limit of detection for carbon is 10 pg/L with an analysis rate of 20 samples per hour. Woelfel and Sontheimer (12N)discussed a procedure for determining organically bound carbon in water using photochemical oxidation. The organic compounds are oxidized at 40 "C by ultraviolet radiation. Concentrations of 1 pg/L of carbon can be detected. 150R
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Bikbulatov ( I N ) outlined an oxidation procedure for organic material in natural water prior to determining organic carbon. An apparatus and optimum conditions are described for this persulfate oxidation procedure. A procedure for the continuous potentiometric determination of oxidizing agents in drinking water is discussed by Malissa and Rend1 (9N).The determination is based on the difference between the redox potential of the water after dosing a continuous stream of the sample with a reagent containing Fe2+/Fe3+and the redox potential of a stream of water containing no oxidizing agents after a similar dosage with the reagent. The isotopic and quantitative determination of the major carbon fractions in natural water samples is described by Games and Hayes ( 4 N ) .Carbon present in natural water is quantitatively transformed into carbon dioxide for quantitation and carbon isotope ratio measurement. Fractions presenting inorganic carbon dioxide, volatile organic carbon, nonvolatile organic carbon, methane, and carbon monoxide are obtained separately with detection limits of 5,5,50,1, and 5 ppb, respectively. The effects of water volume filtered and the number of filters used on the observed concentrations of particulate nitrogen and carbon in marine waters was examined by Gordon and Sutcliffe ( 5 N ) using 47 mm, 0.8 pm silver filters. It was concluded that the best procedure is to filter through single filters using gravity when possible. The optimum filtering volume is generally between 1 and 10 liters. Adsorption of carbon to the filters appears to be negligible.
ORGANICS The direct analysis of water and waste-water samples for organic pollutants with gas chromatography-mass spectrometry was investigated by Harris, Budde, and Eichelberger (29P). Studies were made of the effects of relatively large pressures of water vapor on the well-established electron impact fragementation patterns, quadrupole GC/MS-system performance, interactive background subtraction, and detection limits. It was concluded that direct aqueous analysis is a valuable supplemental procedure for the unambiguous identification of the more volatile organic pollutants in water samples. A computerized gas chromatography-mass spectrometry system for detection of pollutants in all media is outlined by Heller, McGuire, and Budde (3OP).A minicomputer is used for data acquisition, reduction, and control. Computerized search systems and the development of an international mass spectral search system is described. A procedure for determining trace amounts of volatile organics in water by gas chromatography-mass spectrometry with glass capillary columns is presented by Bertsch, Anderson, and Holzer (8P).Traces of volatile organic materials are concentrated by gas-phase stripping and adsorption onto a porous polymer. Sample transfer from the adsorbent into a gas chromatographic column is effected by heat desorption. Compounds less volatile than benzene are usually retained and separations are made with highly efficient glass capillary columns. A portable gas chromatographic technique to measure dissolved (23-6 alkane hydrocarbons in sea water is discussed by Perras (58P).The gas stripping device continuously removes the hydrocarbon vapors from water and injects them into a gas chromatograph. A quantitative, analytical method for concentrating, isolating, and determining volatile hydrocarbon and chlorinated hydrocarbon solvents in water and waste water is presented by Bellar and Lichtenberg (6P, 7P). An inert gas is bubbled through the sample to transfer volatile compounds from the aqueous phase to the gaseous phase. These compounds are then concentrated on an adsorptive material, such as a porous polymer, under noncryogenic conditions and determined by gas chromatography using a flame ionization or microcoulometric detector. The method is applicable to organic compounds that are
