(1017) Wise, W. M., Kurey, M. J., Baum, G., Clin. Chem., 16,103-6 (1970). (1018) Wolf, S., Fresenius’ 2.Anal. C h m . , 250, 13-17 (1970). (1019) Wolf, S., Chem.-Ztg., Chem. App., 93,676-80 (1969). (1020) Woodson, J. H., Liebhafsky, H. A., ANAL.CHEM.,41, 1894-7 (1969). (1021) woodward, B., Taylor, N. F., Brunb. R. V.. Anal. Biochem.. 36, 303-9 (1970 j. (1022) Woudsma, J., Chem. Tech. (Amsterdum), 25,285-6 (1970). (1023) Yamane, I., Sato, K., Sci. Rep. Res. Inst.. Tohoku Univ., Ser. D.,. 21,. 65-77 (1970). (1024) Yamaeoe, F., Nippon Dojo-Hiryogaku Zasshi, 42, 44 (1971). I
.
(1025) Yoshimori, T., Denki Kagaku, 38,869-75 (1970). (1026) Yumatov, E. A., Fiziol. Zh. SSSR im- I . M . Sechaova, 56, 1657-60 (1970). (1027) Yurow, H. W., Sass, S., Anal. Chim. Acta. 52. 537-44 (1970). ~(1028) Zakharova, E. P., Borovskaya, V. S., Kovalenko P. N., Ivanova, Z. I., Fesenko, S. h., Sovrem. Metody Khim. Tekhnol Kontr, Proizvod., 1968, 63-5. (1029) Zaslavskii, B. G., Rybkin, .Y. F., Vedmedenko, V. M., Elektrokhamaya, 6,491-6 (1970). (1030) Zavgorodnii, S. F., Kamyshnikov, I. F., Sovrem. Metody Khim. Tekhnol. Kontr. Proizvod., 1968,51-2.
(1031) Zebreva, A. I., Efremova, G. K., Kozlovskii, M. T., Dokl. Akad. Nauk SSSR, 1 9 3 , 1 3 2 6 8 (1970). (1032) Zebreva, A. I., Matakova, R. N., Kovaleva, L. M., Elektrokhimiya, 6 , 835-8 (1970). (1033) Zegzhda, T. V., Lavrenova, L. G., Ust’yantseva, T. A,, ibid., 5, 1147-50 (1969). (1034) Zegehda, T. V., Lavrenova, L. G., Shul’man, V. M., Ust’yantseva, T. A,, ibid., 6,442-4 (1970). (1035) Zeuthen, T., Acta Physiol. S a n d . , 81,141-2 (1971). (1036) Zinser, E. J., Page, J. A., ANAL. CHEM.42,787-90 (1970). (1037) Znamirovschi, V., Isotopenprazis, 6,29-31(1970).
Kinetic Aspects of Analytical Chemistry Ronald A. Greinke, Union Carbide Corporation, Carbon Products Division, Parma, Ohio 447 07 Harry 0. Mark, Jr., Department of Chemistry, University of Cincinnati, Cincinaati, Ohio 4522 I
T
HIS REVIEW SURVEYS the literature from February 1970 through Deceniber 1971. Some papers published before 1970, which have not appeared in previous reviews in this series, have also been included. Papers pertaining to mechanistic and kinetic studies of reactions were not included unless the results of the studies were used for kinetic analysis. There has been a significant increase in the number of analytical applications of kinetic based methods during the past two-year period. Most of the unique and/or special advantages of reaction rate methods of analysis with respect to conventional equilibrium based techniques, such as the selectivity and sensitivity of catalyzed reaction rate methods, the utilization of reactions which have unfavorable equilibrium constants and/or undergo side reactions, the simultaneous in situ analysis of closely related mixtures, saving of time, etc., have been discussed in the literiature a t great length over the past 10 or 15 years. However, there has been considerable resistance to employing kinetic based analytical methods, except for special problems, because of the obvious problem of adding time as an experimental variable which is necessary in making experimental measurements on dynamic systems. I n the past two years, instrumentation technology, measurement techniques, electronic circuitry, automation methods, and analytical procedures have advanced at a fantastic rate and have reached a high degree of sophistication. These advances are primarily the result of the increase in availability and decrease in the cost of computers,
computer services, and analog and/or digital integrated circuits. These advances have made it possible to attain the measurement accuracy and precision necessary to make dynamic reaction systems applicable to both routine and “special case” analytical problems. The special application of the small digital computers as built-in (on-line) units in chemical instrumentation for data reduction, system control, data acquisition, and especially in experimental optimization and design in red-time is the major factor in making reaction rate based analytical methods practical. Systems have been described in which the computer not only handles the data acquisition and reduction, but takes part in the experiment by real-time examination of the data, and then makes decisions which optimize experimental variables and parameters during the actual experiment. This review classifies the recent literature according to catalyzed reaction methods, uncatalyzed reaction methods, differential reaction rate methods (for mixtures), and instrumental advances. CATALYXD REACTIONS
The use of catalyzed reactions for the determination of a single species in solution is by far the most popular area of kinetic analysis. Catalytic reactions are a very powerful analytical tool because they are capable of extremely sensitive and, in many cases, specific ahalysiu. A review of catalytic reactions was prepared by Bontchev (1). He discussed a number of d s e r e n t
types of catalytic mechanisms with the purpose that it would help in the development of new, improved analytical procedures. Svehla @) has reviewed the kinetic theory and application of Landolt reactions (time required for the appearance of iodine) in quantitative catalytic analysis. Ingle and Crouch (78) presented an excellent paper describing the theoretical and experimental factors influencing the accuracy of analytical rate measure ments for catalyzed reactions. They illustrated that the variable time approach is best suited for rate analysis of catalysts. The number of inorganic cations determined by catalyzed reactions during the two year period is immense. Aleksiev and Bonchev (3) reported that silver a t concentrations down to 1 ppm can catalyze the oxidation of sulfanilic acid by S2082-. The effects of temperature, acidity, and the presence of other metals on the reaction rate have been investigated. Jasinskiene and Rasevichute (4) studied the use of ethylenediamine and triethylenetetramine as activators in determining silver from its catalytic effect on the oxidation of certain azodyes by K2S208. The method, incorporating the use of ethylenediamine, was used to determine the solubility of silver in water. Silver was also assayed by Yasinskene and Yankauskene (6) who reacted catechol violet with K&Oa. The activator, 2,a-bipyridyl was employed for this silver catalyzed reaction. Silver catalyzes the oxidation of sulfanilic acid with persulphate. Bonchev et al. (110) employed this reaction, activated by ethylenediamine, for the determination
ANALYTICAL CHEMISTRY, VOL. 44, NO. 5, APRIL 1972
295 R
of silver in the range of 1 to 35 pg per ml . Various alkyl and aryl esters of HsPOd have been examined as activators for the catalytic activity of alkaline earth metals in the decarboxylation of oxalacetic acid. Mikhailova and Bonchev (6) concluded that the greatest activating effect was obtained with tributyl phosphate in 50% ethanolic medium. These authors (7) also evaluated 2-picoline and 2,4,&collidine as activators for thb catalytic decarboxylation of oxalacetic acid. Based on the results, a method for determining as little as 0.5 pg of aluminum was developed. A selective method for the determination of lo-* to 10-6M calcium in the presence of magnesium was presented by Funahashi, Yamada, and Tanaka (8). It is based on the catalytic effect of calcium on the ligand exchange reaction of Cu(11)-EGTA ((ethyleneglycol) bis-@-aminoethylether)-N,N,N',N'-tetraacetate) with 4(2-pyridylazo) resorcinol. Two methods were presented for the determination of cobalt. Prik and Orlova (9) used the cobalt catalyzed oxidation of catechol with H202 and the activator, p-phenetidine. Cobalt, determined in bovine milk and natural water, was first separated from interfering metals by paper chromatography. Costache's (10) method was based on cobalt catalyzed oxidation of haematoxylin by HzOz. Bilidiene et al. (11) reported a kinetic method for micro amounts of chromium(VI). Chromium catalyzes the oxidation of methyl orange by H202 in an acidic medium. Copper was catalytically determined by a variety of procedures. Hesselbarth (18) assayed for as little as 1 ng of copper(I1) per ml using the iron(II1) thiocyanate-thiosulfate reaction. A simultaneous comparison of the decolorization of sample and standard was employed. This same author (13, 14) reported two procedures for the isolation of copper from interfering metals. I n the first (IS),he employed co-precipitation with mercuric sulfide; while in the second, (14), he used a cation ion exchange resin. After separation, the above-mentioned iron(II1) thiocyanatethiosulfate reaction was utilized. Shigematsu and Munakata (16) applied the copper ion catalyzed oxidation of ascorbic acid for the determination of copper in the range of 27 to 270 ng. The reaction was followed by spectrophotometry at 265 nm. The copper(I1) catalyzed oxidation of amidol with B r O a was the basis for the procedure developed by Suteu et al. (16). Vanadium(V), Fe(III), Mo(VI), and chromate, which also have catalytic activity, interfere. Gregorowicz and Suwinska (17) determined traces of cop296R
0
per(I1) in analytical reagent grade ammonium and sodium salts and in acetic acid. The copper catalyzed oxidation of 3-amino-4-hydroxybenzenesulphonic acid with H202 was used. The oxidation of quinol by Hz02 is catalyzed by copper (11). Pelczar (18) used this reaction for the determination of copper in medicinal tinctures. Weisz and Ludwig (19) determined copper spectrophotometrically in the range of 1 to 25 pg per 10 ml by its accelerating action on the reaction of iron(II1) with thiosulfate. Copper(II), in the range of 1 to 100 pg/ml, was assayed by Pall et al. (20)who used the reaction between peroxidisulfate and iodide. The addition of thiosulfate to this system produced the Landolt effect as i t reacts with the generated free iodine. Several catalytic methods for the determination of iron have been devised. The above-mentioned reaction between peroxidisulfate and iodide, modified by the addition of thiosulfate to produce the Landolt effect, is also catalyzed by iron(I1). The interference from iron in the determination of copper may be overcome by the addition of a masking reagent such as fluoride (20), Kriss et al. (81)determined as little as 1 ng of iron(I1) per ml by the iron catalyzed oxidation of p-phenetidine by H202. This reaction, activated by 1,lO-phenanthroline, was employed to assay iron in vine leaves. Suteu et al. ($2) devised a procedure for the determination of iron(III), which catalyzes the rate of reaction between KBrOs and 2,4diaminophenol. A number of cations interfere. A kinetic method for germanium(1V) described by Alekseeva and Nemzer ($3, 113) was based on the enhancing effect of germanium(1V) on the rate of oxidation of iodide by molybdenum(V1). A number of catalytic methods for manganese have been reported. Bartkus and coworkers ($4, 96) have shown that lead nitrate, in the presence of ethylenediamine, activates the catalytic action of manganese on the oxidation of the sodium salt of carmine by hydrogen peroxide. As little as 0.12 ng of manganese has been determined with an error of = 1%. Bartkus and Jasinskiene (66)have also reported the determination of manganese by its catalytic action on the rate of oxidation of 5-chloro-2hydroxy - 3 - (2,4,6- trioxipyrimidin - 5ylazo) benzenesulfonic acid by hydrogen peroxide. I n a similar study, Sychev and Tiginyanu (27) developed a method for manganese based on the catalytic effect of manganese(II)-l1l0-phenanthrolinq complex on the oxidation of indigo carmine by hydrogen peroxide. Hadjiioannou and Kephalas ($8) described an automated spectrophotometric method, which was based on the potassium periodate-diethyl-aniline reaction catalyzed by manganese(I1).
ANALYTICAL CHEMISTRY, VOL. 44, NO. 5, APRIL 1972
The amounts of manganese in the range 3 to 30 ng were determined with relative errors of 2% and measuring times of only 15 to 1-50 sec. The use of nitrilotriacetic acid to enhance the catalytic effect of manganese(I1) on the oxidation of Malachite Green was reported by Mottola and Harrison (190). The relative standard deviation for 10 determinations of 5 X 1O-sM manganese was 0.8%. Several procedures were reported for molybdenum, based on its acceleration of the rate of oxidation of KI by H202. Shafran et al. ($9) followed the rate of this reaction amperometrically. Fuge (SO) using a Technicon AutoAnalyzer, followed the rate of tri-iodide formation colorimetrically. As little as 0.2 pg per liter was determined in marine and fresh waters, milk and plant samples after dry ashing, and standard rock samples after alkaline fusion. Babko (31) ascertained that the catalytic effect is increased using purified starch as an indicator. The reaction of NaBOs with KI is catalyzed by molybdenum, and was applied by Pelczar and Boleslaw (32) to the determination of 10.8 to 18.8 pg of molybdenum in tinctures. However the error, =t14%, was poor. Pavlova and Yatsimirskii (33) described a spot procedure based on the catalytic effect of molybdenum on the oxidation of dithio-oxamide by HzO2. The reaction is carried out on filter paper and the reflectance of the spot is measured a t 418 nm. The method was applied to the determination of molybdenum in particulate matter from sea water. A kinetic method for nickel was proposed by Dolmanova et al. (34). Nickel catalyzes the reaction between hydrogen peroxide and diphenylcarbazone. Alekseeva et al. (36) described a kinetic method for osmium(VII1) based on its catalytic effect on the oxidation of iodide by bromate in an acid medium. The sensitivity is 40 picograms of osmium per ml. There is no interference from 100-fold amounts of copper, cobalt, nickel, iron, or aluminum, or 10-fold amounts of rut henium . The rate of oxidation of 3,4-dihydroxy-azobenzene, stilbazo or pyrogallol red by SzOe*- in a borate buffer medium is directly proportional to the concentration of lead(I1). Using this reaction, Jasinskiene et al. (36) determined 10 ng of lead per milliliter. Fedorova et al. (37) determined palladium by its catalytic effect on the reaction between tin(I1) chloride and arsenous acid. Kukushkin and Vlasova (38) reported that the decomposition of hydrogen peroxide is catalyzed by palladium. Platinum retards the reaction, which is followed by the measurement of the evolved oxygen.
Ruthenium(IV), which catalyzes the oxidation of I- by HzOz, was determined by Alekseeva and Ignatova (89) in the 0.6- to 2.0-micromole range. Iron(I1) and osmium(VII1) interfere. Yatsimirskii and students (40, 41) presented several methods for the determination of ruthenium. The oxidation of odianisidine by periodate (40) and the oxidation of benzidine by hydrogen peroxide (41) are both catalyzed by ruthenium. Resnik and Bednyak (&) described a method for ruthenium based on its catalytic effect on the reduction of the iron(II1)thiocyanide complex by SnC12. Copper molybdate and fluoride interfere but magnesium(I1) , cobalt (11) , njckel(I1) , and chromium do not. Kawashima, Nakano, and Tanaka (48) used the seleniumfIV) catalyzed reaction between chlorate and phenylhydrazinep-sulfonic acid for the assay of this cation. The pdiazobenzene sulfonic acid formed is coupled with 1-naphthylamine to form an intensely colored azo dyestuff. A kinetic method for titanium, published by Litvinenko (44), is based on the catalytic effect of titanium in the rate of oxidation of I- by HzOZ. Oxalate, EDTA, and fluoride form catalytically inactive compounds with titanium and were employed to stop the reaction for analysis by the fixed time method. A detailed study of the oxidation reaction of bromate with Bordeaux B, catalyzed by vanadium, was presented in a series of papers by Fuller and Ottaway (46-47). The mechanisms and the rate laws for the uncatalyzed (46) and catalyzed (46) reactions were presented. Based on this investigation, a kinetic method for the determination of vanadium(1V) at levels as low as 5 X lo-* pglml was established (47). Interference effects of 37 cations, anions, and complexing agents were examined. Bognar and Jellinek (48-60) have investigated the mechanism of the vanadium catalyzed reaction of bromate and ascorbic acid. The activation energy and the rate law are derived. A variety of approaches were employed to determine vanadium. Thompson and Svehla (61) also used the bromateascorbic acid reaction for the determination of vanadium. A Landolt reaction was employed for measuring the rate of this reaction. Similarly, vanadium was determined by Suteu and Nascu (52) who employed the vamdium(V) catalyzed reaction of bromate and 2,4-diaminophenol. A trace amount of phenol was used as an activator. Christian (68) applied the vanadium catalyzed oxidation of phenylhydrazine-p-sulfonic acid by sodium chlorate for the assaying of this cation in human blood and urine. As little as 0.01 pg/ml was determined after
removal of the interferences by solvent extraction. Omarova (64) reported that the reduction of basic blue K by titanium(II1) is catalyzed by tungsten(V1); 5 X to 33 X 10-8M of tungsten were determined. A limited number of inorganic anions were assayed by catalytic reactions. Takahashi and coworkers (66) determined bromide in silicate rocks by means of its catalytic effect on the oxidation reaction of iodide to 1 0 3 - by KMn04. Rock samples containing less than 0.04 ppm bromide were analyzed, using only 0.25 to 0.5 gram of sample, with an error of *0.03 pg a t the 0.5 pg level. Fluoride inhibits the zirconium-catalysed reaction between perborate and iodide. Klockow et al. (66) employed an automatic potentiostatic technique for determining 19 to 190 ng of fluoride in 50 ml with a standard deviation of h7.4 ng. Knapp (67) reported a kinetic method for fluoride based on its catalytic effect on the zirconiumxylenol orange reaction. Similarly, Hems et al. (68) determined 0.25 to 4.75 pg of fluoride by catalysis of the zirconium-methyl-thymol blue reaction. These latter two reactions were followed spectrophotometrically. A variety of catalyzed reactions were reported for the determination of iodide. Proskuryakova (59) used the oxidation reaction of Fe (SCN)2 by NaN02. Oiwa et al. (60) employed the oxidation reaction of catechol violet by HzOZ; Zoledziowska .(61) reported the reaction of Ce(1V) and As(II1); and Bognar and IUagy (61) described the iodine catalyzed reaction of 3,3'-dimethylnaphthidine with hydrogen peroxide. The silver(1) catalyzed reaction of KzSZO~and the disodium salt of 5-nitro-2- { 3- [4-(sulfophenylazo)phenyl]triazeno ] benzenesulfonic acid, reported by Tamarchenko (68), is inhibited by iodide. Kinetic methods for phosphate, down to the 10-ng range, were described by Yatsimirskii et al. (64) and Rosolowski (66). Both methods employed the phosphate catalyzed reduction of molybdate to molybdenum blue by ascorbic acid. Masalovich et al. (114) kinetically determined 0.01 to 1% of sulfate in phosphoric acid by measuring the time taken to obtain a given absorbance value after adding an acidified BaClz solution. Several organic compounds, cysteine, hydrazine, and alcohols were assayed by catalytic reactions. Cysteine catalyzes the reduction of silver(1) by iron(II), as reported by Babko et al. (66) and also catalyzes the iodineazide reaction, as described by Weisz and Ludwig (19). Suteu et al. (67) reported that the
oxidation of amidol with BrOa-, catalyzed by hydrazine, can be used for the determination of 0.05 mg to 0.5 mg of hydrazine. Other reducing agents will interfere. Kreuger et al. (118) studied the oxidation of tert-butyl alcohol by xenon trioxide. The induction time of the reaction was a function of the ratio of ht-butyl alcohol to XeOa. Twentytwo pg of tert-butyl alcohol was determined with a coefficient of variation of 4%. Methanol, ethanol, and isopropyl alcohol catalyze the reaction by changing the induction time. Many organic substances bond hydrogen and many ligands chelate metals in a way to lower the reduction potential of the hydrogen and metal ion at an electrode, giving rise to a catalytic polarographic prewave. Many papers were published during this period which reported the use of the resulting catalytic current for the sensitive and selective determination of such ligands, metal ions, and organic substances. Alexander and Orth (68) reported the catalytic wave of rhodium(II1) obtained in the presence of cysteine. The method was extremely sensitive for the trace analysis of rhodium, giving a detection limit of 2 X 10-gM. Buckley (69) described the determination of 20 ng to 120 ng/ml of ruthenium after it had been converted to a nitrosyl chloro complex (H [Ru(NO)CLH20]). The standard deviation was *3%. Hojman et al. (70) also determined ruthenium, based on the catalytic reduction wave formed in the presence of rubeanic acid. Ezerskaya et al. (71) observed a catalytic wave in solutions of platinum and EDTA. They polarographically determined 0.16 to 21 pmoles of platinum. Sinyakova and Stepanova (72) proposed a method for niobium(V) based on the catalytic wave of hydroxylamine in the presence of niobium. Milyavskii and Sinyakova (73) polarographically determined nanogram amounts of iron from the catalytic wave for hydrogen peroxide in the presence of the Fe-N,N'-bis-(salicylidene)ethylenediamine complex. The method was applied to the determination of 10-7 to lo-% iron in hydrochloric acid, potassium chloride, and arsenic without prior separation of other impurities. Toropova and Zabbarova (110) determined titanium(1V) by measurement of its catalytic current polarographically observed in a titanium-EDTA solution. Bromate enhances the height of the wave. Tur'yan and Saksin (74) reported that the height of the prewave of titanium(1V) in the presence of citric acid was directly proportional to the concentration of citric acid. The minimum determinable concentration of citric acid was 6 p M and the relative error was less than 57&. Skobets et al. (75) assayed oxalate from the catalytic wave of
ANALYTICAL CHEMISTRY, VOL. 44, NO. 5, APRIL 1972
297R
oxalic acid on a silver amalgam electrode. An infrequently reported type of kinetic method is the titrimetric analysis whose end point is detected by a catalyzed reaction, Le. : Titrant
+ Sample 4Products
Indicator reaction
exoem of titrant (catalyst)
Products Mottola (76) presented a general review which illustrates the usefulness of the catalytic end-point indication of the titrimetric determination of a number of inorganic and organic species. He also applied this technique to the titration of microgram amounts of aminocarboxylic acids (EDTA, HEDTA, DCTA, and DTPA) (77). The exceM manganese(I1) catalyzed the oxidation of malachite green by periodate. UNCATALYZED REACTIONS
Because of lower accuracy, the use of uncatalyzed reactions for the determination of a single species usually is not recommended if a suitable nonkinetic method is available. However, when the reaction that is employed for the classical nonkinetic analysis is quite slow, reversible, or involves an additional interfering consecutive reaction, a kinetic method utilizing initial reaction rates may be advantageous. Ingle and Crouch (78) presented an excellent paper describing the theoretical and experimental factors influencing the accuracy of analytical rate measurements for first or pseudo first order uncatalyzed reactions. They illustrated that, if the reaction monitor is linear with concentration, a fixed time approach is theoretically superior to the variable time approach for pseudo first order uncatalyzed reactions. These same authors also reported a unique application of a kinetic analysis using uncatalyzed reactions (79). They determined 10 ppm or less of silicate and phosphate in mixtures without prior separation. Phosphate and silicate each react with Mo(V1) to form yellow heteropoly acids which can be reduced to heteropoly blues. The initial rate of formation of the heteropoly blue from phosphate was made much faster than the corresponding silicate heteropoly blue under certain experimental conditions. Thus, phosphate was determined without any interference from silicate. Silicate was determined under a second set of conditions by measuring the initial rate of formation of 812-molybdosilicicacid, which forms a t a much slower rate than 12-molybdophosphoric acid. Both species were determined in less than five minutes using an automated reaction rate system. 298R
Tikhonova (80) reported the determination of 2-furaldehyde in the presence of acetone, methanol, and acetic acid by an uncatalyzed reaction with HSOa-. Rodziewice et al. (81-83) described the determination of phenols in several reaction media; ethanol, ethanediol, and propane-1,3-diol. The initial reaction rate, variable time approach resulted in a relative error of 5%. A kinetic method for the determination of uric acid in the 10 to 100 ppm range, described by Cordos and Cirlig (84), was based on the rate of formation of tungsten blue by reacdon of uric acid with standard tungstophosphoric acid solution. Hargis published a fine spectrophotometric study of the formation of ~-12-mo1ybdosilicic acid from the reaction between silicate and molybdate (86). He also presented a mechanistic study of the formation of a-l2-molybdosilicic acid from 8-12molybdosilicic acid (86). As a result of these studies, an initial reaction rate method for silicate was reported based on the formation of the heteropoly complex, ~-l2-molybdosilicic acid (67). The relative precision for 3 ppm of silicon was better than 1%, and for 0.3 ppm, the lower concentration limit, better than 4%. The method required only 10 to 30 seconds of reaction time. The above is an excellent example of the use of initial reaction rates of an uncatalyzed reaction in order to eliminate the error produced by a side reaction, the formation of a-l2-molybdosilicic acid. DIFFERENTIAL REACTION RATES
Differential reaction rate methods continue to be an extremely useful analytical tool for the in situ simultaneous analysis of mixtures with closely related chemical properties. A critical theoretical and experimental evaluation of the limitations of two of the most frequently used methods, the graphical extrapolation and the method of Roberts and Regan, was described by Greinke and Mark (88). The evaluation shows the relationship between the ratio of rate constants of the reacting species and the maximum and minimum tolerable percentage of the faster reacting component in the mixture. These results are guidelines for analysts who use these methods. Willeboordse (89) uniquely employed both the graphical extrapolation method and the method of Roberts and Regan in order to obtain the rate constants of the reaction of primary and secondary hydroxyl groups in polyether and polyester polyols with phenyl isocyanate. Willis et al. (90) described a linear least squares procedure which used a small computer, for the analysis of two- and three-component mixtures of alkaline earth metals. The difference
ANALYTICAL CHEMISTRY, VOL. 44,NO. 5, APRIL 1972
in the reaction rates of the Sr, Ca, and Mg complexes of trans-l,2diaminocyclohexane-N,N,N', N '-tetraacetate in exchange with lead(I1) provided the basis for the metal determinations, The results indicated that the computer processing of a large number of data points from a kinetic run can significantly improve the accuracy of a differential kinetic method. A detailed mechanistic study of the ruthenium catalyzed reaction between cerium(1V) and arsenic(II1) in a sulfuric acid medium was reported by Worthington and Pardue (91). The results of this study provided optimum experimental conditions for the analysis of mixtures of ruthenium and osmium by a method of proportional equations. As low as 2 X lO-'"M of ruthenium and osmium were determined with a relative error of 3%. I n a similar study, Deming (92), using the above ruthenium and osmium catalyzed reaction, graphically illustrated with three-dimensional plots [the rate constant as a function of the arsenic(II1) and cerium(1V) concentrations] the optimum conditions for this analysis. He concluded that the analysis results of the determination of catalytic species by this method of proportional equations, has the best accuracy when the ratio of rate constants is as large as possible in one equation, while the ratio of rate constants is as small as possible in the other equation. Greinke and Mark (93) extended the use of the graphical extrapolation method to include autocatalytic and autoinhibitive reactions. They illustrated, by analysis of amine mixtures, that the order, n, of the amine reacting with methyliodide varied as a function of the reaction media. Shresta and Das (94) analyzed mixtures of primary amines by reaction with salicylaldehyde. An advantage of this method is that secondary and tertiary amines do not interfere. Zaia et al. (96) cleverly employed a differential reaction rate method for mixtures of organo-tin compounds after noting their thermal instability by gas chromatographic analysis. Mixtures of hexabutyl- and hexamethyltin, hexaethyl- and hexamethyltin, and hexabutyl- and hexaethyltin were resolved by reaction with silver(1). The second order graphical extrapolation mathematics were employed. Brook and Munday (96), unable to separate mixtures of methyl ethanesulfonate and ethyl methanesulfonate by gas chromatography, successfully employed the graphical extrapolation kinetic technique for resolution. Mixtures of penicillic acid and penicilloamides were resolved by Schwartz and Delduce (97), who used the graphical extrapolation method and the reagent, HgC12. Delaporte and Laval-Martin (98) analyzed mixtures
of chlorophyll a and chlorophyll b in plant extracts by the graphical extrap olation ditrerential reaction rate method. The spectrophotometric procedure, requiring only 15 minutes, resulted in a relative error of 2%. Yatsimirskii et al. (99)determined mixtures of PrCb and YbCls by measuring Merences in reaction rates of the xylenol orange complexes of these rare earth metals with EDTA. INSTRUMENTAL, COMPUTER, AND OTHER KINETIC METHODS
Sand and Huber (100) demonstrated the electrochemical technique, differential constanbcurrent potentiometry, for kinetic analysis. During a kinetic analysis, the differences in potential between two voltametric electrodes held at different constant currents is monitored. The potential a t each electrode is established by electroactive species corresponding to the current density applied. Shifts in potential occur whenever concentrations in the electroactive species change. An electroactive species undergoing depletion by homogeneous solution reaction exhibits a peak-shaped potential us. time response. The width of the peak is proportional to the initial concentration. This technique was applied to the determination of phenols by bromination and to the oxidation of hydroxylamine by ferricyanide. Many workers have described the use of computers as an effective aid in kinetic analysis. Ingle and Crouch (101) used a fixed time rate computer system for calculating the initial rate of a reaction by digital integration of the output voltage from, for example, a spectrophotometer. Continuous or single measurements can be made over a wide range of input slopes. The described circuit can easily be included in an automated sampling system. Results for the spectrophotometric determination of 3 to 10 ppm of P showed a coefficient of variation from 0.66 to 2.05%. Willis et al. (102) developed a logic control system and interface to link an optically stabilized spectrophotometer to an on-line computer. Various kinetic parameters can be obtained within a few seconds without the introduction of errors from the oscilloscope or operator. They used a stabilized spectrometer, which eliminated the need to periodically adjust the 100% transmittance setting. Two chemical systems were employed as models for analysis based on stoppedflow kinetic measurements: one was the exchange reaction between strontium complex of CyDTA and hydrogen ions with lead(I1) as a scavengef; the other was the reaction between iron(II1) and thiocyanate. Date from the stabilized spectrometer showed a twofold
improvement in standard deviation compared to data from a commercial instrument. Deming and Pardue (103) described a computer technique for kinetic analysis which utilired a low resolution analog to digital converter (ADC) in such a manner that it yielded data equivalent to an ADC with resolution between 14 and 15 bits. This system was evaluated for chemical applications by obtaining kinetic measurements on the reaction between semi-carbazide and 2,6dichlorophenolindophenol a t pH 7.0. The reaction was followed spectrophotometrically at 522 nm. Hicks et al. (1167, Toren et al. (117), and Eggert et al. (118) have discussed the use of a hybrid analogdigital approach to on-line computer operation. They employed a hardware interface to compute the reaction rate “outside” of the actual digital computer. The computer was thus free to monitor the data and control the electromechanical equipment used for sampling, reagent addition, automatic scaling, calibration, timing and sequencing operations, and output display. Eggert et al. (118) also discussed this hybrid system in on-line experimental control operations. An excellent discussion of the principles, objectives, and general design “philosophy” of computer controlled instrumentation for kinetic measurements has recently been published by Deming and Pardue (119). A noteworthy study of ion selective electrodes for following reaction rates under turbulent flow conditions was described by Fleet and Rechnitz (116). This system, capable of following reaction times as short as 10 msec, was used for the measurement of the rates of complex formation of Ca(II), Mg(II), and Ba(1J) with biologically important ligands. Several aids have been reported to improve the speed of automated kinetic analysis. Varley and Baker (104) reported a reliable electronic timer that controls the operation of the Technicon AutoAnalyzer. This timer, which controls the samp!e and wash operations, resulted in a 30% increpe in the analysis rate for automated determinations. Dawson et al. (105) described an attachment to a commercial chart reader that facilitated the measurement of gradients of sloping traces resulting from reaction rates. A voltage is generated, by this attachment, that is proportional to the gradient of the recorder trace. Two advantages were found using this attachment: one, a two- to five-fold increase in the measurement rate; and two, a reduction in operator fatigue. Several commercial instruments and modified commercial instruments were used for kinetic analysis. Husbands (106) employed the Unicam AC60 for the automated determination of en-
~ymes,while Lalor (107) used a Zeiss
PMQ I1 spectrophotometer. Hexter and Hand (108) improved the scanning mechanism of a rapid scan infrared spectrophotometer, which WM designed for flash photolysis kinetic spectroscopy. Keene et al. (109) describe an improved photomultiplier and amplifier circuit for a spectrophotometer used for flash photolysis measurements. LITERATURE CITED
(1) Bontchev, P. R., Tahnfa, 17, 499
(1970). (2)Svehla, G.,Analyst (London), 94, 513 f1969). (3)qleksiev, A. A., Bonchev, P. R., Mzerocham. Acta, 1970, 13. (4)Jasinskiene, E., Rasevichute, N., Zh. Anal. Khim., 25, 458 (1970). (5)Yasinskene, E.,Yankauskene, E., Tr. A M . Nauk Litov. SSR, 9 41 (1968). (6)Mikhailova, V., Bonchev, P. R., Mikrochim. Acta., 1970,688. (7)Ibid., p 344. (8) Funahashi, S.,Yamada, S., Tanaka, M., Anal. Chim. Acta., 56, 371 (1971). (9)Prik, G.A.,Orlova, M. N., Uch. Zap. Vladimir. Gos. Ped. Znst., 22,48 (1970). (10) Costache, D., Rev. Roum. Chim., 15, 1161 (1970). (11)Bilidiene, E. B., Chepelenite, .Y., Jasinskiene, E., Tr. Akad. Nauk Lztov. SSR., 10, 55 (1969). (12)Hesselbarth, H., 2 . Anal. Chm. 248. 163 (1969). f 13) Ibid.. D’167. (i4j Ibid.; h 289. (15)Shigematsu, T., Munekata, M., Bull. Inst. Chem. Res. Kyoto Univ., 48, 198 (1970). (16)Suteu, A., Crisan, I. A., Pop, E., Rev. h u m . Chim:, 15, 1337 (1970). (17)Gregoromcz, Z., Sumnska, T., Chem. Anal. (Warsuw), 15, 295 (1970). (18)Pelczar,. T.,, Acta Pol. Phamn.,. 26,549 . (i969). (19)Weisz, H.,Ludwig, H., Anal. Chim. Acta, 55, 303 (1971). (20)P&ll, A., Svehla, G., Erdey, L., Tulanta, 17,211 (1970). (21).Knss, E.,Savichenko, Y.,. Yatsimmkii. K. B.. Zh. Anal. Kham.,. 24,. 875 (1969). ‘ (22)Suteu, A., Crisan, I. A,, Kiss Z., Stud. Univ. Babes-Bolyai, Ser. Chm., 14, 57 (1969). (23)Alekseeva, I., Nemzer, I. I., Zh. Anal. Khim., 24, 1393 (1969). (24)Bartkus, P. I., Jasinskiene, E. I., ibid., 23, 1622 (1968). (25)Bartkus, P. I., Kaleanikdte, S., Jasinskiene, E. I., Tr. Akud. Nauk Litsov SSR, 10, 15 (1969). (26) Bartkus, P.,Jasinskiene, E., Nauch. Tr. Vyssh.. Ucheb. Zaved. Ldov. SSR, Khim. Khim.-Tekhml., 11, 83 (1970). (27)Sychev, A,, Tiginyanu, Y., Zh. Anal. Khim., 24, 1842 (1969). (28)Hadjiioannou, T. P., Kephalas, T. A., Mikrochim. Acta, 1969, 1215. (29)Shafran, I. G.,Rozenbl um, V. P., Shteinberg, G. A,, Tr. NauchXssled. Inst. Khim. Reakt., Osobo Chist. Khim. Veshchest., 31, 171 (1969). (30)Fuge, R.,Analyst (London), 95, 171 (1970). (31)Babko, A. K., Lisetskaya G. S., Tsarenko, G. F., Zh. Anal. Kflim., 23, 1342 (1968). (32)Pelczar, T., Boleslaw, J., Acta Pol. Phurm., 26, 319 (1969). (33)Pavlova, V. K., Yatsimirskii, K. B., Zh. Anal. Khim., 24, 1347 (1969). (34)Dolmanova, I. F.,Zolotova, G. A., Kabanova, T. P., Peshkova, V. M., ’
des.
ANALYTICAL CHEMISTRY, VOL. 44, NO. 5, APRIL 1972
299R
Vest. Mosk. &OS. Unw., Ser. Khim., 6, 96 (1968). (35 Al&va, I. I., Smirnova, I. B., Jataimirskii, K. B., Zh. Anal. Khim., 25, 539 (1970): (36) Jasinskiene, E., Kalesnikaite, S., w..D 87. (37 F(dokva, T. I., Shvedova, L. V., datsimirskii K, B. W . p 307. (38) Kukuahkh p. k., Vhova, R. A., Zh. Prikl. Kham.. Lmmw., - , 41.. 2293 (1968). (39) Alekseeva, I. I., Ignatova, .N. K., Uchen. Zap. Mosk. Zmt. Tonkoa Kham. Tekhnql., 1, 59 (1970). (40)Kahma, V. E., Yatsimifskii, K. B., Zunma. T. S.. Zh. Anal. Kh%m..24. 1178
(63) Tamarchenko, L. M., Zh. Anal.
Khim., 25, 567 (1970). (64) Yateimirskii K., Rmolovskii, S., ~ r i e sE. E., a&,, p 324. (65) Rdsolowski, S., Chim. A d . (Warm ~ )15, , 157 (1970). (66) Babko, A. K. Markova, L. V., Maksimenko, T. d., Zh. Anal. Khim., 23, 1268 (1968). (67) Suteu, A., Crisan, I. A,, Mhdrutiu, E., Rev. R a m . Chim., 15, 1187 (1970). (68) Alexander P. W., Orth, G. L., J . Ehroanal. dhha., 31, A p. 3+ (1971). (69) Buckley, J. P., Anaf Chzm. Ada, 52, 379 (1970). (70) Hojman, J., Stefanovic, A., Stankovic. B.. Zuman. P.. J . Eledroanul. Chem:, 30, 469 (1971).’ (71) Ezereka a, N. A., Kiseleva, I. N., Zh. Anal. ghim., 24, 1684 (1969). (72) Sinyakova, S. I., Stepanova, I. K., W.,23, 1405 (1968). (73) Milyavskii, Y., Sinyakova, S., ibid., D r 1183. (74) Tur’ an, Y., Saksin, E., W., 25, 998 (19?0). (75) Skobets, E. M., Chernyi, V. A., Drutstsa, P. I., Tr. Nikolaev. Korabbstrod Inst., (36), 167 (1970). (76) Mottola, H., Talanta, 16, 1267 flg69). (77j-M6ttolaI H., ANAL.CHEM.,42, 630 (1970). (78) Ingle, J. D., Jr., Crouch, S. R., ANAL. CHEM.43, 697 (1971). (79) Zbid.. D 7. (80j TikhGova, V. I., Zh. Anal. Khim., 23, 1720 (1968). (81) Rodziewicz, W., Kwiatkowska, I., Kmatkowski. E.. Chem. Anal. (War.saw), 13, 1067 (1968). (82) Zbid., p 1305. (83) Ibid., 14, 55 (1969). (84) Cordos, E., Cirlig, E., Stud. Univ. Babes-Bolyai, Ser. Chem., 15, 13 (1970). (85) Hargis, L. G., ANAL.CHEM.,42,1494 (1970). (86) Ibid., D 1497. (87) Ha&, L. G., Anal. Chim. Acta., 52, 1 (1970). (88) Greinke, R. A,, Mark, H. B., Jr., ANAL.CHEM.,39, 1577 (1967). (89) Willeboordse, F., J . Phys. Chem., 74, 601 (1970). - -,(gojwillis, G. B., Woodruff, W. H., Frysinger, J. R., Margerum, D. W., Pardue, H. L., ANAL.CHEM.,42, 1350 (1970). (91).Worthington, J. B., Pardue, H. L., zbzd., p 1157. \ - -
,-”--,. (61) Zoledziowska, Z., Chem. Anal. (Warsaw), 15, 1037 (1970). (62) Bognar, J., Nagy, L., Mikrochim. Acta, 1969, 108.
(92) Deming, 8. N.,ibid. 43,1726 (1971). (93) Greinke, R. A. dark, H. B., Jr., W . 39,1572 (196t). (94) Shreate, I. L., Das, M. N., A d . Chim. Ada, 50, 135 (1970). (95) Zaia, P., Peruzzo, V , Lazzogna, G., W , ,51, 317 (1970). (96) Brook, A., Munday, K., Analyst (London),94,909 (1969). (97) Schwartz M., Delduce, A., J . Phurm. Sci., 58, 113b (1969). (98) Dela orte, N., Laval-Martin, D., Anal. d i m . Ada. 55, 425 (1971). (99) Yatsimirskii, k. Budarin, L. I., Khachatryan, A., bokl. A M . Nauk SSSR, 195, 898 (1970). (100) Sand, J. R., Huber, C. O., ANAL. CHEM.,42, 238 (1970). (101) Ingle, J. D., Jr., Crouch, S. R., Bittikofer, J., Pardue, H., M a r g e m D., ibid., p 1340. (103) Deming, i., Pardue, H., aid., p 1466. (104) Varley, J. A., Baker, K. F., Analyst (London),96, 734 (1971). (105) D a m n , J., Fisher, G., Annan, W., ibid., p 380. (106) Husbands, A. P., Spectrovhion, (23). 13 (1970). (107)’Lalo< G. C., Lab. Pract., 19, 607 (1970). (108) Hexter, R. M., Hand, C. W., Appl. Opt. 7, 2161. (1968). (109) keene, J. P., Black, E. D., Hayon, E., Rm. Sei. Znstrum., 40, 1199 (1969). (110) Toropova, V., Zabbarova, R., Zh. Anal. Khim., 25, 1059 (1970). (111) Bonchev P. R., Aleksiev, A. A., Dimitrova. f.. Mikrochim. Acta. 1970. 1104. (112) Kreuger, R., Vas, S., Jmehkis, B., Talanta, 18, 116 (1971). (113) Alekseeva, I., Nemzer, I., Zh. Anal. Khim., 25, 1118 (1970). (114) Masalovich, V. M., Agasyan, P. K., N. Kolaeva, E. R., Tr. Ural. NauchIssbd. K h m . Znst., 19, 173 (1970). (115) Fleet, B., Rechnitz, G., ANAL. CHEM.,42, 690 (1970). (116) Hicks, G. P., Eggert, A. A., Toren, E. C., Jr., ibid., (117) Toren, E. E gert, A. A., Sherrv. A . E.. kicks. P.. Clin. Chem:.’16. 215 i1970). ’ (118) Eggert, A. A., Hicks, G. P., Davis, J. E., ANAL.CHEM.,43,736 (1970). (119) Demina. -, S. N., Pardue, H. L.. ibid.. . p i92. (120) Mottola, H. A,, Harrison, C. R., Takanta, 18, 683 (1971). \-_.
I
,
a’?:,
8
8.
I - - -
Light Absorption Spectrometry D. F. Bok, Wayne State University, Detroit, Mid. M. G. Mellon, Purdue University, La fayetfe, Ind.
T
HE APPLICABILITY OF SPECTROPHOTOME-Y to the determination of
traces of metals, nonmetals, and organic substances is one of the main reasons for the continued widespread utilization of this opticometric method of analysis. Reliable low cost instrumentation, speed, satisfactory accuracy and precision, and suitability for automation are additional factors contributing to the popularity of spectrophotometric 300R
analysis. This review records the sigiiificant developments in analytical, light absorption spectrometry for the period from November 1969 through November 1971, as documented by Chemical Abstracts. The subject matter has been classified under the topics of Chemistry, Physics, and Applications, aa in the previous reviews (103, 494, 496)* The extensive literature cited in this
ANALYTICAL CHEMISTRY, VOL. 44, NO. 5, APRIL 1972
review attests to the large number of relevant publications which have appeared in this biennium. It has been necessary to evaluate carefully all papers and abstracts and to cite only those references of most probable significance to analytical chemists. Although hundreds of papers of scientific merit have not been mentioned because they were judged to be either of limited applicability or repetitious, this review
