Ryland, L. B., ANAL. CHEM.32, 1002 (1960). (184) Tamele, M. W., Ryland, L. B., McCoy, R. N., Ibid., 32, 1007 (1960). (185) Tochstein, A., Pecka, R., Collection Czechoslov. Chem. Communs. 25. 2115 (1960). (186) Tutundzic, P. S., Paunovic, N. M., Paunovic, M. M., Anal. Chim. Acta 22, 345 1960j.
(187) Urbafiski, T., Chem. Anal. (Warsaw) 5,687 (1960). (188) Van Meurs, N., J. Electroanal. Chem. 2 , 17 (1961). (189) Voorhies, J. D., DaviB, S. M., ANAL.CHEM.32, 1855 (1960). (190) Vydra, F., PEibil, R., Talanta 5, 44 (1960). (191) Ibid., p. 92. (192) Wegmann, D., Lyssy, G. H., Simon, W., Helv. Chzm. Acta 44, 25 (1961).
(193) Wen. 1...T. Wen, W.-Y.. W.-Y., Klotz. Klotz, I. 3 M., J . Phvs. Phys. ' &em. Chem. 65; 65, 1085 (1961). (194) Wiessner, W.,Kandler, D., Beckert, W.,Acta Imeko 4, 414 (1959). 36, (195) Wilson, R. H., J . Sci. Instr. 36. (1959).' 424 (1959). (196) Wolf, S., Osferr. Chem. Ztg. 61, 292 (1960). (197) Fqood, K. I., ANAL.CHEM.32, 537 (1960). (198) Woiniak, J., Roczniki Palistwowego Zakladu Hig. 12, 33 (1961). I
-
~
7
-
~
d -
'
Review of Fundamental Developments in Analysis
Volumetric and Gravimetric Analytical Methods for Inorganic Compounds W . H. McCurdy, Jr., Universify o f Delaware, Newark, Del.
T
HE large number of publications each year describing advances in gravimetric and titrimetric analysis of inorganic materials indicates the continued interest in this branch of analytical chemistry. I n accordance Lvith the viewpoint taken by the previous authors of this review, comments have been restricted to papers describing new procedures or valuable improvements in old procedures during the period August 1959 to December 1961. The author recognizes that many worthwhile contributions to specific analysis problems may have been omitted.
GRAVIMETRIC ANALYSIS
The discrepancy which exists between the types of new reagents described and those needed in analysis has been the source of much comment. Selective precipitants for palladium, copper, zirconium, and thorium continue to appear in abundance. Widespread application of new chelating agents has revived interest in many nonspecific precipitants under masking conditions. Investigation of pertinent equilibria and kinetic features of these reactions will show the advantages and limitations of this approach. Tandon and Bhattacharya (123) have shown that bis(2-thiophene-trans-aldoxime) palladium(I1) chloride may be precipitated from hydrochloric acid solution with very few interferences, Interference of cerium(1V) was removed b y reduction to the trivalent state, but some difficulty was encountered with reduction of other platinum elements to the free metal. The reagent is stable, water-soluble, and more selective than dimethylglyoxime. A recent review of tetraphenylborate chemistry b y Flaschka and Bernard (98) has been published. Several work-
322 R
ANALYTICAL CHEMISTRY
ers have described the analytical properties of other borate derivatives. The preparation of lithium tetra-p-tolylborate has been reported (109) and applied to the determination of sodium. The other alkali metals also precipitate and must be separated with lithium tetraphenylborate. Havfi: (51) determined the solubilities of several triphenylcyanoborates. The cesium, thallium(I), and silver(1) salts were quantitatively precipitated in the presence of potassium and ammonium salts, but extensive coprecipitation of rubidium occurred. Investigation of other modifications of this reagent should prove interesting. N-Benzoyl - N -phenylhydroxylamine introduced by Shome (114) for precipitation of aluminum, copper(II), iron (111), and titanium has received considerable attention. The beryllium (d7), cobalt, nickel (116)) molybdenum (VI) (117), niobium(V) (68, 7 d ) , tin(1V) (101), and zirconium (6, 100) salts are stoichiometric and may be dried at 110' C. Scandium (4, thorium, and cerium(II1) (115) precipitates must be ignited to the oxide. Many separations are feasible using p H control and masking conditions. The improved characteristics of this cupferron analog will doubtless find many other applications in the near future. Attempts to separate various metals b y selective reduction with sodium borohydride at controlled p H were only partially successful (110). Zinc was not reduced a t any pH; cadmium was reduced in the p H range 2 to 7 ; lead a t p H 5 to 6. Mixtures of lead-barium, cadmium-mercury, cadmium-zinc, and lead-zinc were studied. The idea is interesting and may find useful application in effecting preliminary separations.
Jain and Singhal (68) have summarized research on 2,5-dihydroxy-1,4-benzoquinone and related compounds. This reagent selectively precipitates thorium and zirconium from 1X hydrochlsric acid in the presence of titanium and rare earths (60). Other elements are precipitated as the p H is increased (69). I n most cases the precipitates are nonuniform in composition and must be ignited to the oxide. Many other less selective reagents have been described. For example, Szabadvhry, Takhcs, and Erdey (120) report precipitation of tin, zirconium, thorium, and iron in strong acid, manganese, lead, copper, mercury, cadmium, zinc, nickel, and cobalt a t p H greater than 2.5 and silver, magnesium, and uranium(V1) in neutral solution with 4-hydroxyl-3-nitrophenylarsonic acid. Such behavior strongly limits application of the reagent to practical analysis situations. Precipitation from Homogeneous Solution. I n addition to the classical hydrolysis technique, a number of other methods have been described for gradual cation or anion release in homogeneous solution. These include displacement from masking agent (40, 41), oxidation of masking agent (go), reduction of cation (SO), evaporation of masking agent (58,S9), and evaporation of solubilizing solvent (9, 55). Howick and Jones (55) recommend the latter technique for separations where close p H control is required. Zinc 8-quinolinol was separated from magnesium b y slowly evaporating acetone from a carefully buffered solution. The most elegant technique involves in situ synthesis of precipitant from component chemicals in the presence of the metal cation. This method has been applied to precipitation with dimethylglyoxime (61, IO@, l-nitroso-
2-naphthol (62), and N-phenylnitrosohydroxylamine (53). T h e procedure should be applicable to any synthetic reaction which can be carried out under conditions required for quantitative precipitation. Nightingale and Benck (88) report the preparation of crystalline p-FeO(0H) from dilute iron(II1) chloride complexed with N,N‘-dihydroxyethylglycine upon hydrolysis of urea. Some difficulty was encountered in obtaining both crystalline precipitates and quantitative recovery of iron. Swift and coworkers have continued their fine studies on metal sulfide precipitation with thioacetamide. Bowersox, Smith, and Swift have shown that nickel ( l a ) and zinc (13) sulfides precipitate b y a direct reaction mechanism described earlier for lead and cadmium. The rate constants are nearly inversely proportional to the metal sulfide solubility product. Zinc also was precipitated by the indirect hydrolysis-controlled mechanism but nickel was not. The kinetics of alkaline hydrolysis of thioacetamide were described by Peters and Swift (91). Preliminary measurements of rate of sulfide formation indicated that alkaline hydrolysis of thioacetamide and direct reaction of the metal with thioacetamide mere occurring simultaneously. King and Anson (63) obtained specific acid catalysis of the thioacetamide hydrolysis reaction in the p H range 4 to 6 by introduction of hydrazine. This effect may be useful in the separation of weakly acidic sulfides from basic sulfides. A recent review of thioacetamide chemistry has been written b y Swift and Anson (98). A survey of metals separated by precipitation from homogeneous solution is given in Table I. Recent findings suggest that “precipitation from homogeneous solution” may be somewhat misleading terminology. Kucleation and precipitation measurements on silver chloride formed by slow hydrolysis of allyl chloride have been described by Klein et al. (64). The ion product calculated from conductance measurements and the known rate of hydrolysis of allyl chloride was found to exceed the equilibrium ion product by several times during initial stages of precipitation. I n a study of physical factors which influence the number of crystal nuclei, Fischer (43) emphasized the importance of undissolved reagents, contamination, container walls, and inert electrolyte as nucleation sites. This viewpoint was extended by a microscopic study of the number of particles of cadmium sulfide, lead sulfide, and barium sulfate in solution a t various stages of precipitation of these compounds from homogeneous solution (42). The evidence obtained (at 50% confidence level) indicates that nucleation is completed within the first 30 seconds of reaction
and all further reaction occurs as growth on these nuclei. For these examples Fischer concludes that precipitation from homogeneous solution has little control over the number of crystal nuclei. Haberman and Gordon (60) held the opinion, based on the work of Klein and others, t h a t Fischer’s conclusions are not valid for most cases of precipitation from homogeneous solution. This discussion will undoubtedly be resolved as more experimental evidence becomes available. It is obvious that unless precautions are taken in the preparation of reagents, sites for nucleation will be largely predetermined. On the other hand particle count experiments could be extended to more soluble precipitates where the rate of precipitant formation might be expected to have a more profound effect on the rate of nucleation. Coprecipitation. Measurements of extent of coprecipitation of strontium and lead with barium sulfate formed b y hydrolysis of sulfamic acid were performed by Cohen and Gordon (22). The results follow a log distribution relationship v-hich permits reasonable predictions of contamination to be made. Bowersox, Smith, and Swift (12, I S ) have provided convincing proof that coprecipitation of zinc on lead sulfide and nickel on lead and cadmium sul-
Table 1.
fides formed b y hydrolysis of thioacetamide at p H 0.5 occurs via the direct reaction mechanism. Because the direct reaction is inhibited b y hydrogen ion, the separation should be made at the lowest p H value which permits quantitative recovery and the precipitate should be removed as soon as it has completely formed. During an investigation of conditions for separation of copper, cadmium, and zinc b y precipitation of sulfides with thioacetamide, McCurdy et al. (’71) noted other factors which may be important. A better separation of zinc from copper(I1) sulfide was obtained in trichloroacetic acid buffer than in hydrochloric acid of lower pH, suggesting some protective action. On the other hand, the amount of zinc coprecipitated with cadmium sulfide under various thioacetamide conditions was noticeably larger than with hydrogen sulfide procedures and 8 to 10 times larger than expected for the direct reaction of zinc and thioacetamide at this acidity. The authors proposed the formation of a limited solid solution of zinc in cadmium sulfide to explain these results. The slow precipitation of tungsten(VI) oxide by decomposition of peroxytungstate in nitric acid was reported by Dams and Hoste (25) to yield a good
Precipitation from Homogeneous Solution
Element Technique Conditions Aluminum Hydrolysis 8-Acetoquinoline, pH 5 Barium Hydrolysis KzCr107, urea, pH 3 Cation displacement K~Cr04,EDTA, MgClz EDTA, MgSOI, pH 9
Separation“ Mg, Cu, Cd
Bismuth
Pb
Hydrolysis Cation release Hydrolysis
Formic acid, urea EDTA, (XHa)HzPO,, HiOz, pH 3 HPOI, 0.05M “01
Ca, Sr, Pb, Fe Ca
- Sr -_
- Pb
Reference (56, 7 5 ) (89) (41)
(40) (19) (80)
Cd, Zn, Mg, Cu, ( 9 9 ) Fe, - Zr, Sb, Sn
Cobalt
Synthesis
Copper
Cation reduction
Halide
Volatilization of masking agent Phosphate Volatilization of masking agent Nickel Synthesis Niobium
Hydrolysis Anion oxidation
Palladium
Synthesis
Thorium
Hydrolysis Volatilization of solvent
Uranium Zinc
Hydrolysis
double ppt. Pb Fe, W
2-Naphthol, HXOz, NaF, pH 3 h-aBPh4, ascorbic acid, - Ag, Hg PH 1 AgTOa, NH3, pH 9.8 - I, Br, C1 10.2, pH 8.6-8.7 AgNOs, h ” 3 , pH 8
(62)
Biacetyl, hydroxylamine, Cu, Co, - Fe pH 7.5 (?rTH4)2CzO4,XaF, urea 3,3’,4’,5,7-PentahyZr, Mo droxyflavanone, - Ti, Ta 6-9hl HC1 Biacetyl,hydroxylamine, Ni, Pt
(103)
iH 3-Acetyl &hydroxy-
(38) (39)
(66) (21 1 (61)
8-. cetoxyquinoline, pH 5 Rare earths
(182)
coumarin in ethanol, PH 2 8-9cetoxyquinoline, pH
Mg, Pb
(11)
Many metals - Co, Xi
(67)
5
Cation displacement Thioacetamide, EDTA hydrolysis CaC12, pH 9
+
(30)
V,rare earths
(9)
- indicates interference. VOL. 34. NO. 5, APRIL 1962
323 R
separation from molybdenum(VI) and vanadium(V), provided the solution temperature remained below 60' C. From the errors observed, contamination was believed to occur b y a surface diffusion process. Coprecipitation has become a standard technique in trace analysis. Recently Merrill et al. ('77) reported the use of iron(II1) or manganese(1J') hydrous ovides dispersed in a n ion exchange column to collect beryllium from large quantities of sea rvater. Ziegler (1%) has employed an anion exchange column containing sulfate to precipitate 3- to 150-mg. amounts of lead in the presence of 50% methanol. The precipitate may be eluted from the column n-ith dilute sodium hydroxide and determined without interference from niany common metals. A similar procedure was devised for separation of silver from bismuth, copper, and large amounts of lead, employing an anion cschange column treated n it11 saccharinic acid (134). Silver saccharinate was eluted n-ith dilute ammonia. Improvements in the collection of traces of platinum and palladium in a tin-copper-nickel matte (36) and palladium, platinum, osmium, and ruthenium in an iron-copper-nickel button (62, 105) by fire assay procedures have pointed out the value of this classical technique. It might be possible to apply zone refining technology to this problem n.ith further improvement in the isolation of platinum metals. Thermogravimetry. Muller (83) has described a new automatic recording balance of commercial manufacture which is well suited to thermogravimetric studies. T h e thermogravimetric method has received a much needed critical examination for sources of error. Changing buoyancy effects. variable gas atmosphere, and temperature fluctuation due to heat liberation or absorption by the sample are some of the errors discussed by Ken-kirk (87). hlost errors are caused by application of heating rates vhich are too high for the particular sample and sample holder. Garn and Kessler (46) describe a simple holder which allon-s gas to escape from the sample but minimizes exchange with the surrounding atmosphere. Striking examples are s h o ~ ~ -ofn differences in thermograms obtained in air us. in the sample holder. Results must be considered in light of the type of information desired. A number of workers have reported new drying temperatures for different compounds. Wendlandt (128) has obtained thermograms on a number of (ethylenedinitri1o)tetraacetates using slow heating rates. Anhydrous disodium dihydrogen tetraacetate may be dried a t 168' to 230" C. in contrast to the 135" C. upper limit statild by Duval. Kendlandt and Ewing (130) recommend 324 R
ANALYTICAL CHEMISTRY
Element Reagent Aluminum Embelin dmmonium Tetraphenylboroii Beryllium
Acetoacetanilide 2,2 '-Dimethylhex-
ane-3,5-dione
Bismuth
Cadmium Cerium Cesium
Cobalt Copper
Conditions pH 4.2 pH 2.0, dry 100" C. pH 5.5, EDTA, dry 110" c. pH 7 . 5 EDTA
-41, Ca, Ti, Fe, Ce. Nd. TJ
(80)
(70)
pH 7 , dry 110" C.
Many metals - Mn, Cr, Fe, Sb. Sn. Th. U.'Zi~ i i metals y - < l o % Pb Ca, Sc, A1, Cr, Fe -&In - Many metals
pH 7, ignite t o oxide
- Many metals (116)
S-Benzoyl-Xphenylhydroxylamine Dimethylglyoxime
pH 6, dry 110" C.
Annnonium naphthyl selenonate 1,lO-Phenanthroline NH4SCN 1-Phenyltetrazoline5-thione S-Benzoyl-Sp h e q Ihydroxylamine Ammonium permanganate Hevachlorotellurous acid A'-Benzoj l-AVphenylhydroxj-lamine m,fi-Hydroxyiminobutyranilide 3-Hydroxy-3-phenyl1-p-tolyltriazen
0.2.U HNOJ
o( p-Tolyleulfon-
pH 6.5, tartrate, dry 110" c. pH 2.5, tartrate, dry
an1ido)aniline 3-Oximinomethylsalicylic acid
pH 11! EDT-1, dry 125O c.
pH 3.5, EDT.A
pH 6.5, dry 110" C. pH 2.5, SO,-', F-, tartrate, dry 125' C.
110° c.
Gold
Thioglycolic acid
Mercury
.\,.V'-I)iallylthiocsrbamoylhydrazine .V-Benzo yl-.Vphenylhydroxylamine a ,0-Dioximino-butyro-o-tolriidide
pH 3, EDTh
.\-Cinn a inoyl--Y-
pH 5, EDT.4, dry
Siobiuin
phcnyltij-drouylamine
(93)
(82)
11-12M HC1, deconip. in moist air SH?OH. pH 6, dry lloo c .
Lithium chloride
Nickel
(119)
Excess reagent, 0" C.
Fluoride
Rlolybdenum
Table II. GraviSeparation" Reference Be (95) Initial separa(34) tion as NH3 -41, Fe (26)
95cc ethanol, dry 110" c . 6AVHCI, dry 115" C
Pdb ..
12.9 i
~
\
-
~
,
- Xi, NO3Ti, Fe, Zr. 110, (48) Ce,-Sb, Sn, Bi - k'd Many metals (10) - Sh, Bi - yjb 98 CdrZn, M n ,Co, \
I
Fe, Sb, Bi, -is
SO, -2
(27)
Many metals (84) Os, Ir, Ru, Pd - Pt. Zr Many metals (34) Agb
2 M HCl, EDT.4, dry 150" c. pH 5
lloo
c.
105' to 110" C. for drying iron(I1) ethylenediammonium sulfate. The minimum temperature for ignition of aluminum oxide is 1200' C., according to Milner and Gordon (79) compared with a 611' to 672" C. range suggested b y Duval. Quinolinium phosphomolybdate was reevamined and found to exist as a monohydrate u p to 107" C. and the anhydrous material to 370" C. (131). Plutmium(1V) sulfate was shown to he a suita1)le neighing form for this clement (127). Indirect determination of a mixture of calcium, strontium, and barium oxalatcs from a therniogravinictric curve was found to be accurate to 1 2 . 0 to 10% on small samples according to Erdey et al. (3.5).
T', Cr, Fe, Ca,
(117)
Xi, Cu - C , Ga, In. \IMg, Zn, Hg, 128) Cd, Cit Pdb
- Ti, Zr, 110, IT,
(7.3)
Sn.Sb
-4study of rare earth cupferrates (129) revealed no distinguishing features nhich would permit thP determination of a mixture of these clcments. GRAVIMETRIC DETERMINATION
A survey of new or niodified gravimetric determinations of various elements is presented in Table 11. In addition, several gravimetric determinations which have been critically evaluated are briefly discussed. Alkali Metals. After preparation of a number of sulfonic acid derivatives, Gowda and Stephen (47) discovered 5-benzaminoanthraquinone-2sulfonic acid to be the most sensitive reagent for sodium that is known.
metric Separation
Element Osmium
Reagent Tetraphenylarsonium chloride or Benzyltriphenylphosphonium chloride Palladium Dialkyldithiocarbamidohydrazine 4-Methyl-2-thiazolvlthiourea 2-Thio"phene-trmw aldoxime Potassium .V,.V'-Dimethylethanol-ammonium orotate Platinum Dimethylphenylbenzyl ammonium chloride Rhodium Copper powder Hexamine cobalt(111)nitrate Scandium
Conditions HC1 solution
Separation" Rh, I r - RU
Reference (86)
pH 2, EDTA, dry 105' C. HC1 solution ..
pH 1, F-, O - ~ C -tar, - Ce, Ag, Sn (123) trate, dry 125" C. Au, Pt, Os, Ru pH 7, 3" C., 80% meth- Al, Fe, CO,Ni, (113) m o l ,, drv- 105' C. cu -Li. Ka. Ca HBr solution, dry (152) 80" C. 1.031 HCl at 90' C. 1 . O M HCl, NaN02, vac
Ir
(124)
hIercury(1) chloride
20y0 HC1, KBr
Fe, Ni, Cu, Os, (31) Pd, Pt - Co., Kr., Rub I r Ir (69)
Mandelic acid
pH 2.5j ignite to oxide
Rare-earths, T h ( 3 )
pH 5.5, dry 110" C.
- Many metals
(92)
pH 5.4, ignite to oxide
- RIany metals
(4)
pH 8.5, EDTA pH 5.0, EDTA, ethanol pH 3, 0" C., volumetric finish HBr, KBrOa, tartrate, volumetric finish pH 4.0, ignite t o oxide pH 8, dry 110" C.
Ca - Ba Many metals
(8) (1)
Rare earths Al
(94) (23)
pH 4, ignite to oxide
U
(67)
pH 5, ignite to oxide
Zr, Tib
(115)
0.2-234 HCl, (collect on
Fe, Co, Ni, Mn, (78) cu - hlo, V, Ti, Nb, Cr Ti, Cr, Nb, T a ( 6 , 100) - V, Sn, Ce
Nercaptobenzothiazole S-Benzoyl-N-phenylhydroxylanline Strontium Magnesium sulfate Ammonium sulfate Sodium a-Methoxyphenylacetic acid Thallium Diantipyrinylmethane Thorium o-Bromobenzoic acid 8-Hydroxyquinaldine 5,5'-Intiigodisulfonic acid S-Benzyl-S-phenylhydroxylamine Tungsten Tributylamine, (NK)&PO, Zirconium N-Benzoy1-Nphenylhydroxylamine 1-Hydroxycyclohexane carboxylic acid Thioglycolic acid Thiomalic acid
dried
cellulose column) dry 190°
c.
2-4M HCI, dry at 110' C.
- Pt,
- Zr
- Many metals - Many metals
(97)
2116 HC1, ignite to oxide Bi, Th, V, Sn, U,
(9)
0.2-0.4111 HC1, ignite to
(108)
rare earths
oxide 0.2N HCl, ignite to oxide
Many metals - Th, CeIV Many metals - Hg, Bi, Thb
(107)
- indicates interference. Interference removed by prior separation.
Unfortunately, the compound is not selective. The use of a-methoxyphenyl acetic acid is novel in that sodium is the only common elenlent that crystallizes as an acid salt. Thus volumetric determination of sodium may be accomplished in the presence of many ions t h a t form precipitates. Reeve (91)has described the sources of error in this method and recommended a correction factor. Schwartzenbach and Geir (112) have investigakd the formation of potassium sodium decavanadate as a potential method for sodium. A stoichiometric compound is obtained even in solutions containing very large potassium-sodium ratios. Alkaline Earths. I n a review of
analytical methods for beryllium, Smythe and Whittem (118) concluded that the ammonium phosphate and 8-quinolinol methods were most accurate. Radiotracer determination of coprecipitation of sodium and potassium with magnesium compounds by Heyn and Finston (54) revealed that magnesium 8-quinolinate gave the best separation. E D T A masking was advocated b y Schulek and Endroi-Havas (111) for the separation of magnesium ammonium phosphate from iron, aluminum, and calcium. After making a eomparison of methods for strontium, Ford (44) recommended precipitation of calciumstrontium oxalates followed by extraction of calcium with 80% nitric acid.
Rare Earths. As a result of conflicting reports, Broadhead and Heady (14) performed a statistical study to determine the optimum pH, oxalic acid concentration, and digestion time in order to obtain complete precipitation of rare earth oxalates. The rare earth concentration (less than 0.01X) and p H 2.0 were found to be the most important factors. Gusinskaya (49) compared the iodate and oxalate methods for cerium(II1) using radio tracers. Although the oxalate method permitted a good separation from manganese, chromium, and iron, the iodate method was required to obtain a suitable separation from nickel. Titanium - Zirconium - Uranium. hIurphy et al. (86) have made a very careful investigation of the separation of titanium, zirconium, iron, and aluminum in barium titanate ceramics. Meadows and Matlack (76) report the significant details involved in the separation of zirconium from plutonium with p-bromomandelic acid. Sulfur dioxide m-as employed to remove tellurium and reduce plutonium(1V) to the trivalent condition. ,4 different uranium(V1) compound with 8-quinolinol was noted by Bordner, Salesin, and Gordon (11) lvhen precipitated from honiogeneous solution, [U02(0,)2]2H0,,compared with conventional procedures, GO~(O,)~IIO,. Solvate-type 8-quinolinates formed n-ith scandium, thorium, uranium, and plutonium(1V) have been subjected to x-ray analysis b y Van Tassel et al. (126). Evidence mas obtained that the solvated molecule is bound differently in the case of uranium. Niobium-Tantalum. T h e separation of these elements has received considerable attention over the years. Sormally they are separated together-for example, in 111.1 sulfuric acid with N-benzoyl-N-phenylhydroxylamine using peroxide to mask titanium (68). It was shown b y l l a j u m d a r and Nukherjee (72) that the combincd oxides dissolved in tartrate a t n pH less than 1.5 yielded a precipitate of only tantalum upon addition of N-benzoylN-phenylhydroxylamine. Kiobiuni v as recovered with the same reagent in the pII range 3.5 to 6.5. Using a double precipitation, 100 to 1 ratios of these elemcnts were resolved. These results have been confirmed by Langnillir and Hongslo (68) and hIajumdar and Pal (74)' Nickel Cobalt Cadmium. I n a study of t h e separation of nickel from cobalt (66), Korotun found that cobalt reacts appreciably fastm Kith dimethylglyoxime than nickel in acid solution. Contamination was reduced by oxidation of cobalt(I1) to the trivalent condition with persuliate in ammonia solution followd b y acidification and precipitation of nickel a t p H 5 . Gravimetric determination of cobalt
-
-
VOL. 34, NO 5 APRIL 1962
325 R
as the violet modification of cobalt ammonium phosphate was recommended b y Foster and Williams (46) after separation of interferences. Kallmann’s procedure for cobalt was evaluated by Salyer and Sweet (104) using Goa radiotracer. Rate measurements showed that precipitation should be made in a hot solution of acetic acid and potassium nitrite of not more than 200-ml. volume. Tartrate and fluoride masking permitted the quantitative separation of cobalt from 15 common elements. DeVoe and Meinke (32) made a survey of decontamination procedures for cadmium. The crystalline precipitate of cadmium thiourea complex with Reinecke’s salt a t p H 3 was found to contain only silver, mercury, thallium, and selenium in amounts exceeding 1% among 19 elements examined. Precipitation of cadmium with 2(o-hydroxyphenyl)benzoxazole suffered from extensive interference of cobalt and ruthenium and to a smaller degree cerium, zinc, antimony, and iodide. Comprehensive studies of this type could be profitably extended to many other elements. Platinum Metals. A critical review of methods for separation of platinum metals was published by Beamish ( 6 ) . In another review ( 7 ) Beamish examined the gravimetric methods for gold. Precipitation of the metal with hydroquinone was ranked as the best general procedure. Thioglycolic acid has recently been proposed b y Mukherji (84) for the selective precipitation of gold from 6M hydrochloric acid. The reaction apparently involves reduction of trivalent gold to the monovalent state. A reinvestigation of the precipitation of sulfo salts of the platinum metals b y Sant et al. (106) has proved this method to be incapable of the precision and accuracy claimed b y Taimni and Salaria (121). The latter workers have developed a large number of thio salt separations employing sodium sulfide (102) which must be reviewed in the light of this criticism. Nonmetals. In agreement with many others, Cannon (18) found the phosphomolybdate method for phosphate to be inexact. Addition of the phosphate sample to the molybdic acid rather than the reverse and drying the precipitate at 130” C. for 2 hours were suggested improvements. The quinoline phosphomolybdate method designated by Wilson for microdetermination of phosphorus has been extended to the milligram range b y Fennel1 and Webb (37). The interference of boron in gravimetric silica determination was overcome b y evaporation of the sample with hydrochloric-nitric acids and glycerol. Pasztor (90) demonstrated that the silica is dehydrated properly, while boron remained complexed. It was
326 R
ANALYTICAL CHEMISTRY
also noted that adsorption of molybdenum, titanium, vanadium, and zirconium was materially reduced by this modified procedure. TITRIMETRIC ANALYSIS
Examination of the current literature describing titrimetric procedures for inorganic components reveals that nearly 70% employ a chelometric process either in the quantization step or in some auxiliary capacity. (Ethylenedinitri1o)tetraacetate (EDTA) occupies a position in solution chemical analysis comparable to that held b y gas chromatography in physical methods of analysis. While excellent new studies continue to appear, there is much that is repetitious or limited in scope. Titrations employing coulometric, amperometric, potentiometric, or thermometric techniques are not included. Acid-Base a n d Precipitation Titrations. T h e interesting application of carbonic anhydrase to permit rapid alkalimetric determination of carbon dioxide was reported b y Underwood (241). This enzyme catalyzes the slow hydration step in this reaction to an extent that complete titration may be accomplished within 2 minutes. Selective blocking of this reaction by certain cations and anions is suggestive of other analytical applications. From a re-examination of the formaldehyde procedure for ammonium salts, Stockdale (233) recommends overtitration with base followed b y backtitration after allowing time for complete formation of hexamethylenetetramine. Strahm and Hawthorne (234)describe a rapid oxidation procedure for borohydrides using trifluoroperoxyacetic acid in acetonitrile. The excess strong acid may be easily differentiated from boric acid b y titration to p H 6.3, addition of mannitol, and completion of the determination. Several attempts have been made to determine metal chelates extracted from aqueous solution b y a nonaqueous titration. The successful conductometric titration of metal 8-quinolinates with potassium methoxide in ethylenediamine solvent was recorded b y Underwood and Underwood (242). Errors averaging 0.9% were obtained in the determination of aluminum, magnesium, scandium, vanadium, molybdenum, and zinc. Because the titration curves were nonlinear, end points could not be located by extrapolation. Perhaps the use of other solvents might improve this condition, The improved color change resulting from the application of a n acid-base indicator and a dye of constant color has been known for many years. Recent quantitative treatment of this subject by Reilley et al. (221) permits
the preparation of screened indicators in a rational manner. Equations were derived based on the tristimulus diagram, Beer’s law, and pertinent equilibrium constantswhich completely characterize the color quality of indicator action. From this analysis, proper concentrations of appropriate indicator pairs may be mixed so as to obtain the end point color at the desired point in a given titration. As the authors point out, other qualifying factors such as variable color memory, nonlinearity of Beer’s law a t different wavelengths, ionic strength, and solvent effects make rigorous use of the theory somewhat difficult. Sastry and Pratt (224) have employed a mixture of 4 parts copper pht“locyanine-4,4’,4’’,4”’-te tkasulfonate and 1 part methyl orange as a screened indicator for carbonate titration. Modest errors amounting t o 0.2y0 were obtained. Bishop has derived equations which allow simple calculation of chemical and indicator errors in titration of strong acid-strong base, weak acid-strong base and TTeak basestrong acid (143). Interest has been noted in chemiluminescent indicators recently. Turowska (239) has prepared several N,N’-alkyl acridine derivatives which yield a yellow-gray chemiluminescence that is quenched by dilute base in solutions containing small amounts of hydrogen peroxide. A mechanism for chemiluminescence of lucigenin involving metal ion catalyst and perhydroxide ion has been proposed by Erdey and BuzCts (167). The indicator ceases to emit light when the catalyst is masked or the indicator adsorbed on a substrate. The latter effect has been employed in microtitration of iodide in ammoniacal solution containing chloride and bromide with a precision of 0.2%. Diresorcinoldiphenyl pyromellitein was observed to yield sharp end points in the argentometric titration of halides in 1111 nitric acid (144). The color change (yellow to purple) is said to be visible in colored solutions. Bobtelsky and Carmon (145) have devised a selective microheterometric determination of bismuth in the presence of 14 common elements. Addition of thiocarbanilide (TCA) to a dilute nitric acid solution containing potassium iodide results in precipitation of a compound having the formula Bi(TCA)&. Puschel and Lassner (220) have reviewed the numerous applications of chelatochrome indicators in precipitation titrations. Oxidation - Reduction Titrations. T h e mechanisms of many common analytical redox reactions are not completely understood. Duke (164) postulates that electron transfer proceeds concurrently with or immediately after an acid-base reaction. Many bridge intermediate and atom transfer
mechanisms appear to fit this reaction sequence. Duke suggests that this viewpoint may assist in the prediction of p H effects and choice of catalysts. The kinetics of the iron(II1)-vanadium(II1) reaction catalyzed by copper (11) salts and the cerium(1V)-mercury (I) reaction catalyzed b y silver(1) salts were presented a t a recent symposium b y Higginson et al. (182). Mechanistic arguments are given for transient formation of copper(1) and silver(I1) in these reactions. McCurdy and Guilbault (199) first reported the enhanced rate effect obtained b y use of a mixture of silver(1) and manganese(I1) salts in the slow ccrium(1V) sulfate oxidation of mercury(1) perchlorate. Both silver(I1) and manganese(II1) and possibly higher oxidation states of these elements are believed to be present in this reaction niechanism. Beneficial effects of the silver(1)-manganese(I1) catalyst system have been obtained in the cerium(IV) sulfate oxidation of metal 8-quinolinates (180),hypophosphite, phosphite, and tellurite (181). An improved hydrous cerium(1V) oxide for preparation of stable cerium solutions was described by Diehl and Smith (162). The process depends on careful drying over a period of 2 to 3 weeks. As a result of conflicting reports in the literature, Grant and Payne (17‘9) have reinvestigated the decomposition of cerium(1V) sulfate in sulfuric acid a t boiling temperatures. Decomposition was found to be catalyzed by surface indicating a radical mechanism. Although the results were difficult to reproduce, a 1% loss in strength per hour was observed in lilf sulfuric acid. The reaction of sodium vanadate and titanium(II1) chloride in hydrochloric acid solution WAS examined by Murty and Rao (205). Addition of oxalic acid was noted to have little effect on the titanium(II1)-titanium(1V) redox potential but a large effrct on the rate of reduction of oxidized phenosafranine indicator. A procedure was developed for precise determination of titanium(111) in inert atmosphere in the presence of iron employing this indicator. Kennedy (188) quantitatively reduced uranium(V1) to uranium(II1) in nitrogen atmosphere with amalgamated zinc and 1Jf hydrochloric or perchloric acid. The equivalent amount of iron(I1) produced in a ferric alum collecting solution was determined by dichromate titration. Sulfate was shown to seriously interfere with complete reduction t o the trivalent oxidation state. Combination of this procedure with a n air oxidation procedure was suggested as a means of analyzing mixtures of titanium or iron and uranium. An exhaustive study of errors in the Lingane-Karplus method for manganese(I1) in neutral pyrophosphate media has been pub-
lished by Scribner and Scribner and Anduze (228, 219). No suitable visual indicator has been reported for this useful and highly selective determination. Schulek and coworkers (148, 226) have conducted a series of investigations on the fundamentals of bromatebromide oxidation. It has been shown that bromine, bromine monochloride, and chlorine mixed with bromine monochloride are formed as the chloride to bromide ratio is increased. Reactions are interpreted in terms of nucleophilic us. electrophilic character of the reaction intermediates. A 1,M hydrochloric acid solution containing 100% excess of bromine monochloride was found to yield stoichiometric oxidation of hydroxylamine within 0.5%. The first titrimetric method for determination of mixtures of hydrazine and methylhydrazine has been developed by Clark and Smith (155). Differential oxidation of the mixture was accomplished by treatment of aliquot portions of sample with chloramine T and sodium hypochlorite. Chloramine T in hydrochloric acid undergoes a 4-electron reaction with both compounds while hypochlorite in buffered phosphate requires 4 electrons in reaction with hydrazine and 8 electrons in reaction with methylhydrazine. Results show a precision of 0.1%. Unsymmetrical dimethylhydrazine could not be determined with either method. A review of the many applications of ferricyanide oxidation in titrimetric analysis was written b y Sant and Sant (223). Preparation of Variamine Blue (4-amino-4’-methoxydiphenylamine) sulfate has resulted in a redox indicator of improved stability over the free base (168). An elegant determination of very slight deviations in oxygen stoichiometry in crystalline manganese, cobalt, and nickel oxides by iodometry has been described by Sachse (222). Wolf, Franz, and Hennig (255) have employed a reductimetric titration of iron(II1) thiocyanate in hydrochloric acid using an ethanol solution of ferrocene and 2,4-dinitro-N-phenylpyridinium chloride indicator. The method was applied to the determination of milligram amounts of iron in the presence of 25 common elements. Only copper(II), peroxide, and fluoride interfere. An interesting application of ion exchange resins to oxidation-reduction titrations was reported by Erdey, InczBdy, and Markovits (169). Quantitative reduction of iron(II1) salts was effected b y adsorption on a cation exchange column and treatment TTith ascorbic acid. After removal of excess reductant, iron(I1) was eluted from the column with dilute sulfuric acid. A second method employed an anion exchange column pretreated with tin(I1) chloride in hydrochloric acid. Passage of a n iron(II1) solution in 3M hydrochloric
acid through the column resulted in reduction of iron and retention of tin(I1) and tin(1V) chloro complexes. Chelometric Titrations. Although a certain amount of lore has developed concerning favorite procedures of end point detection, masking, a n d demasking, continued progress has depended heavily on increased understanding of fundamental principles. Schmrtzenbach (227) surveyed the different structural modifications of polyamino-N-carboxylic acids and related compounds and the significant facts that have been learned. He concludes that in order to design a reagent which forms complexes that are both stable and selective, a structure must be created to exactly fit the steric requirements of the ion in question. A summary of some of the major advances in selective chelonietric titration are presented b y West (249). Such a titration not only requires a selective titrant but also selective masking and a selective indicator. The conditional formation constants of various metals with (diethylenetriamine) pentaacetic acid (DTPA) and ethylene glycolbis(p-aminoethyl ether)N,N’-tetraacetic acid (EGTA) are compared with E D T A as a function of p H b y TT’anninen (247). The superiority of EGTA for selective determination of calcium in the presence of magnesium was shown theoretically and demonstrated experimentally. The importance of kinetic considerations in complex formation has been reflected b y the increasing number of publications on this subject. One such study b y hlargerum et al. (201) describes the stepwise displacement of EDTA from nickel(11) by cyanide ion. The slow stt,p in the series of reactions was identified with the conversion of a n octahedral paramagnetic complex into a planar diamagnetic complex. It may be anticipated that investigations of this type will lead to useful analytical methods. Masking. Sodium-2,3-dirnercaptopropane sulfonate (245) and thioglycolic acid (118) are reported to be excellent masking agents for sulfide-forming elements. Formation of a n intensely colored iron(II1) thioglycolate complex was prevented b y addition of triethanolamine. It is somewhat surprising t h a t chromium(II1) forms an ascorbic acid complex which is suitable for masking this element. Pfibil and Vesely (216) consider the comparatively weak color of this complex to be a considerable advantage over the deep red chromium triethanolamine romplex. Phosphate interference in the chelometric determination of calcium was eliminated b y addition of molybdate to a n ammoniacal solution of the sample (203). A thorough review of masking agents and masking action has been published b y Cheng (164). Although much of the information in this paper is VOL 34, NO. 5, APRIL 1962
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ANALYTICAL CHEMISTRY
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qualitative in nature, i t will be very useful in the development of many selective titrations. The selective reaction of zirconium with Xylenol Orange and hydrogen peroxide, but not hafnium, represents a striking example of n h a t has been donr. Cheng has defined a selectivity ratio (p~I,)*/(pM,) which gives a more reliable picture of the competition betn-cen the principal complexing agent for metal ions (-If9)and masking agent for metal ions (M,) than that obtained by comparison of foimation constants. The important effects of nonequilibrium condition? remain ignored. Antiblockinp of indicators such as Eriochrome Black 'I' by 1,lOpheiianthroline (o-phen) hay lx en dcw i b e d by PEibil (218). iZpparcntly only labile indicator complexes are formed when some of thc coxdination positions are occupied h y (o-phen). Similar antiblocking action has bcen reported using cupferron, glycine, o-phenylenediamine, and other cornpounds in acetate buffer (149) Indicators. A large number of new indicator reactions have been inyestigated. T h e improved water solubility and indicator equilibrium constants of 4-(2-p3 rid>-lazo)resorcinol, (PAR) over 1-(2-pyridylazo)2-naphthol, (PAN) are summarized by Iwamoto (185). l-(2-Thiazolylazo)2-resorcinol described by Svoboda (235) has indicator properties similar to PAR. Svoboda, Dorazil, and Korbl (237') have studied 2,6-dibromophenolindo-o-creeol6-niethylaminediacetic acid and recommend it for titration of bismuth, iron, scandium, and thorium a t p H 3. Diehl and Ellingboe (161) and Lindstrom and Diehl (196) have investigated the reactions of o,o'-dihydroxyazo dyes TT ith calcium and magnesium. Of these
4-methy1-2-phenylazo-2-naphthol-4-sulfonic acid (Calgamite) has considerably improved stability over Eriochrome Black T. A diazotized A'-acid of 8-hydroxyl- l-aminonaphthalein-3,6-disulfonic acid designated Calcichrome by Close and West (156) complexes calciuni selectively in the presence of strontium and barium at pH 13. This indicator yields a satisfactory end point n i t h 1,2-diaminocyclohexanetetraaceticacid (DCTA) b u t not EDTA. Fritz, Abbink, and Payne (175) have described 7 - (6-sulfo - 2-naphthylazo) - 8- hydroxyquinoline-5-sulfonic acid (Naphthyl Azoxine S) as an excellent indicator in both acid and basic solutions. A very similar compound (SNAZOXS) has been evaluated b y complimentary tristimulus colorimetry b y Reilley et a l . (221) along with a number of chelometric indicators. Indicators of this type are often sensitized by addition of known amounts of copper to the sample solution. Pfibil (214) has suggested t h a t decarboxylation is probably responsible for the gradual decomposition of 3,3'VOL. 34, NO. 5, APRIL 1962
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bis(N,N - dicarboxymethy1)aminomethy1-o-cresolsulfonethalein (Xylenol Orange) in aqueous solution. Further study might reveal a structurally similar compound with greater stability. A considerable amount of research has been directed toward the preparation of fluorescent chelometric indicators in a pure form. These indicators are generally more sensitive than the conventional type and are particularly applicable to highly colored solutions. Svoboda, et al. (236) have employed a 4 : l mixture of Calcein and phenolphthalein to eliminate the residual fluorescence of free Calcein a t the end point. Kilkins (252) has described the interesting sequence of fluorescence effects with Calcein Blue in acid and basic solution. The free indicator fluoresces a t all p H values u p to 11 and is quenched by addition of transition metal ions. Above p H 12 a reversal effect occurs whereby a n alkaline earth metal indicator complex now fluoresces but the free indicator does not. Similar observations have been reported by Belcher, Rees, and Stephen (141) in a study of N,N,N’,N’-tetracarboxymethyl derivatives of benzidine and Eggers (165) who prepared iminodiacetic acid .derivatives of 4-methylumbelliferon (Calcein Blue) and 3,6-dihydroxyxanthon. Eggers has also shown that the sodium fluorescence displayed by indicators of the Calcein type is strongly temperature-dependent and may be virtually eliminated a t 80’ C. Several mechanisms and indicator complex structures have been proposed (166, 251) which lack sufficient experimental proof a t the present time. Other end point devices have been effectively applied in certain cases. Cameron and Gibson (151) determined milligram amounts of copper, nickel, iron, and vanadium by backtitration of excess EDTA with standard cobalt at p H 9. A sensitive end point is obtained by extraction of the triphenylmethylarsonium salt of tetrathiocyano cobaltate(I1) into a small volume of chloroform. Aikens et al. (136) have performed selective titrations by extrapolation to a photometric end point. A copper indicator complex may be adjusted to yield theoretical equivalence points in the resolution of mixtures by control of ammonia concentration. Results accurate to 0.5Y0 were obtained for calcium-magnesium mixtures using EGTA and 1 to 2% for cadmium-zinc mixtures using DTPA. Photometric titration of copper and nickel in N,N-dimethylformamide with l-nitroso2-naphthol has been described by Takahashi and Robinson (W58). The similarity of the complex and free reagent spectra prevented extension of the method to lead, uranium, and zinc. Manning and Menis (200) report an accuracy of 1% in the determination of 330 R
ANALYTICAL CHEMISTRY
thorium with EDTA employing a new recording 190-Mc. high-frequency Titrimeter. Titration a t p H 2.8 was successful in the presence of iron(II), aluminum, and rather large amounts of electrolyte. Joussot-Dubien and Oster (186) applied an interesting photochemical process to EDTA titrations. Thionine or methylene blue in a nitrogen atmosphere is not reduced by exposure to strong light in the presence of metal EDTA chelates but rapid discoloration occurs after the addition of a slight excess of EDTA. The method was applied to a direct titration of aluminum, iron, and lead. The stability of coordinated chelating agents to ouidation or reduction has also been demonstrated b y Beck and Seres (140). Indirect determination of certain metals was effected by permanganate oxidation of excess oxalate or E D T A a t suitable p H without destroying the metal complex. Separation and Determination. T h e determination of nickel and aluminum by (N-hydroxyethyldinitrilo) N ,N ,N‘triacetic acid (HEDTA) titration and fluoride displacement-copper backtitration at p H 4.8 and manganese b y E D T A titration in tartrate media at p H 9.5 without any prior separation and using only Methyl Calcein indicator (250) illustrates the effective use of selective titrant and masking action. As alternatives to selective masking, precipitation, extraction, or ion exchange offers an infinite number of possibilities. A classification system such as that suggested by Cheng (164) should be of assistance in the selection of the best approach to a given problem. Of the various methods, ion exchange possesses general applicability to many analytical separations. Jones (185) described the determination of nickel, copper, zinc, and cadmium in silver solder following elution from a 100- to 200-mesh anion exchange column. A Dowex A-1 chelating resin was employed effectively by Olsen et al. (209) to separate trace amounts of calcium from lithium salts. Recently Wilkins and Smith (254) and Fritz and Pietrzyk (176) have shown the gain in separation factor obtained by use of hydrochloric acid-alcohol-water mixtures in ion exchange chromatography. Precise separation of three- to five-component mixtures of transition metals in 50- to 100-ml. volumes of eluate were demonstrated (176). A survey of new or improved titrimetric methods is given in Table 111. Several additional publications of a more critical nature should be mentioned. Powell, Fritz, and James ($12) reported cadmium acid (N-hydroxyethyl)N,N,N’-triacetate as a dual primary standard for bases and for E D T A after oxidation with boiling persulfate. The compound was conveniently pre-
pared in pure form and dried a t 110’ C. In view of the large number of papers describing various E D T A procedures for calcium and magnesium, a careful evaluation of this analysis was obviously needed. Lewis and Melnick (196) found that accurate determination of calcium was obtained by titration of 95% of the calcium content before adjusting the p H to 12.5. Comparative analyses were made on several National Bureau of Standards samples. I n a study of the successive titration of iron and aluminum with EDTA, Davis and Jacobsen (151) confirmed the observations of Sweetser and Bricker which showed some interference of aluminum with an accurate determination of iron. As a result of theoretical predictions an improved photometric titration was performed using 5-sulfosalicylic acid indicator a t p H 1. On the other hand, Kydahl (2008) has proved that the aluminum EDTA chelate is not displaced by backtitration with zinc or iron when such an error is expected from equilibrium calculations. These results are interpreted as evidence for an inert aluminum EDTA structure. A number of indirect procedures have been proposed for determination of nonmetals. D e Sousa has applied the tetracyanonickelate(I1) method originally proposed by Huditz and Flaschka to the rapid analysis of bromatebromide mixtures (160) and chloridethiocyanate-cyanide mixtures (159) with a n accuracy of 1%. Complexometric determination of sulfate by precipitation of lead sulfate appears to have some advantages over barium chloride procedures. Sporek (252) investigated the rapid precipitation of lead sulfate from isopropyl alcohol-nitric acid solution. The precipitate may be separated from most interferences except phosphate and molybdate, dissolved in excess EDTA, and backtitrated with zinc. Quantitative recovery of tellurium dioxide was obtained from an EDTA-masked solution a t p H 4.5 according to Cheng (155). The solubility of the precipitate is increased by fluoride and citrate but not by EDTA. The determination may be completed gravimetrically or by cerium(IV) sulfate oxidation (181). LITERATURE CITED
Gravimetric (1) . , Afanas’eva. L. I.. Zhur. Anal. Khim. 15, 564 (1960). ’ (2) Alimarin, I. P., H&n,H. H., Ibid., 16, 162 (1961). (3) Alimarin, I. P., Shen, K., Ibid., 15,31 (1960). (4) Alimarin, I. P., Yung-Schaing, T., Talanta 8, 317 (1961). ( 5 ) Alimarin, I. P., Yun’-Syan, T., Zhur. Anal. Khim. 14. 574 (1959). (6) Beamish, F. E., T a k a 5 , 1 (1960). (7) Ibid., 7, 85 (1961). (8) Berhk, L., Munich, J., Collection
(55) Howick! L. C., Jones, J. L., Talanta 8, 445 (1Y61). (56) Howick, L. C., Trigg, W. W., ANAL. CHEM.33, 302 (1961). (57) Jain, B. D., Singh, J. J., Talanta 8, 648 (1961). (58) Jain, B. D., Singhal, S. P., J . Znorg. Suclear Chem. 19, 176 (1961). (59) Jain, B. D., Singhal, S. P., J . Sci. Znd. Research (India) 19,495 (1960). (60) Jain, B. D., Singhal, S. P., Talanta 4, 17s tiofin) (61) K:mner. L. J.. Salesin. E. D.. Gordon. L., Zbid., 7, 288 (1961). ' (62) Kavanagh, J. M., Beamish, F. E., Izvest. Vysshikh Ucheb. ZavedniZ, Khim. ANAL. CHEM.32, 490 (1960). i Khim. Tekhnol. 3, 69 (1960). (63) King, D. M., Anson, F. C., Zbid., (16) Caley, E. R., Deebel, W. H., ANAL. .YUlJ. 33, 572 (In@" CHEM.33, 309 (1961). (64) Klein, D. H.. Gordon. L.. Walnut. (17) Caley, E. R., Kahle, G. R., Zbid., 31, T. H., Talanta 3; 177, 187 (1959). 1880 (1959). (65) Korotun, M. V., Ukrain. Khim. (18) Cannon, P., Talanta 3, 219 (1960). Zhur. 26, 377 (1960). (19) Cartwright, P. F. S., Analyst 85, 216 (66) Kosta, L., Dular, M., Talanta 8, (icm). 265 ( *"VI,. lacl) (20) Zbid., 86, 688 (1961). (67) KIriin. C. C.. den Boef. G.. Anal. (21) Chan, F. L., Talanta 7, 253 (1961). Chim. 2cta 23, 35 (1960). (22) Cohen, .4. I., Gordon, L., Zbid., 7, (68) Langmyhr, F. J., Hongslo, T., Zbid., 195 (1961). 22, 301 (1960). (69) Lloyd, K. W.,Morris, D. F. C., Talanta 8, 16 (1961). (70) Lott. P. F.. Vitek. R. K.. ANAL. . CHEM.32, 391 (1960). ' (71) McCurdy, W. H., Jr., Vanden HeuVal, W.A. J., Casazza, A. R., Ibid., 31, 1413 (1959). (72) Majumdar, A. K., Mukherjee, A. K., Anal. Chim. Acta 19, 23 (1958). (73) Zbid., 22, 514 (1960). (74) Majumdar, A. K., Pal, B. K., Zbid., 24, 497 (1961). (75) Marec, D. J., Salesin, E. D., Gordon, L., Talanta 8, 293 (1961). (76) Meadows. J. W. T.. Matlack.' G. M.. ' ANAL. &E>;. 32, 1607 (1960). (77) Merrill, J . R., Honda, M., hrnold, J. R., Zbid., 32, 1420 (1960). (78) Miller, C. C., Thow, D. H., Talanta 8, 43 (1961). (79) Milner, 0. I., Gordon, L., Zbid., 4, 115 (1960). (80) Moiseeva, L. M., Kuznetsova, N. M., PalBhina, I. I., Zhur. Anal. Khim. 15, 561 (1960). (81) Montgomery, H. A. C., Analyst 8 5 , 687 (1960). (82) Moore, C. E., Robinson, T. A., Anal. Chim. Acta 23, 533 (1960). (83) Miiller, R. H., ANAL. CHEM. 32, No. 3, 97A (1960). (84) Mukherji, A. K., Anal. Chim. Acta 23, 325 (1960). (85) Murphy, T. J., Clabaugh, W. S., Gilchrist. R.. J . Research Natl. Bur. Standards 64A, 535 (1960). (86) Neeb, R., 2. anal. Chem. 177, 20 (19601. ( 8 7 ) Newkirk, A. E., ANAL. CHEM.32, 1558 (1960). (45) Foster, A. G., Williams, W. J., (88) .Sightingale, E. R., Benck, R. F., Anal. Chim. Acta 24, 20 (1961). Zbzd., 32, 566 (1960). (46) Garn, P. D., Kessler, J. E., ANAL. (89) Norwitz, G., Zbid., 33, 312 (1961). CHEM.32, 1563 (1960). (90) Pasztor, L. C., Zbid., 33, 1270 (1961). (47) Gowda, N. S., Stephen, W. I., Anal. (91) Peters, D. G., Swift, E. H., Talanta Chim. Acta 25, 153 (1961). 1, 30 (1958). (48) Gupta, H. K. L., Jain, T. C., Sogani, (92) Pirtea. T. I.. Rev. chim. (Bucharest) N. C., J . Indian Chem. SOC.37, 531 ' 11, 336 (1960).' (19601. .----, (93) Pirtea, T. I., 2. anal. Chem. 184. (49) Gusinskaya, S. A., Zzvest. Vysshikh 252 (1961). Ucheb. ZavedniZ, Chernaya Met. 3, (94) Rao, C. B., Umapathi, P., Venkates193 (1960). warlu, V., Anal. Chim. Acta 24, 391 (50) Haberman, H., Gordon, L., A 4 ~ ~ ~ . (1961). CHEM.33, 1801 (1961). (95) Rao, C. B., Venkateswarlu, V., 2. (51) . . Havif. J.. Collection Czechoslov. Chem. anal. Chem. 178.277 (1960). Communs. 26, 1775 (1961). (96) Ray, 8 . K:, Riy, P:, J . Indian (52) Heyn, A. H. A., Brauner, P. ii., Chem. SOC.37, 133 (1960). Talanta 7, 281 (1961). (97) Reeve, W., ANAL. CHEM.31, 1066 (53) Heyn, A. H. A., Dave, N. G., Zbid., (1959). 5, 119 (1960). (54) Heyn, A. H. A., Finston, H. L., (98) Rehley, C. X., ed., "Advances in AXAL. CHEM.32, 328 (1960). Analytical Chemistry and InstrumentaCzechoslov. Chem. Communs. 26, 276
(1961). (9) Bhat, A. N., Jain, B. D., Talanta 4, 13 (1960). (10) Billman, J. H., Janetos, N. S., Chemin, R., ANAL. CHEM. 32, 1342 (1960). (11) Bordner, J., Salesin, E. D., Gordon, L., Talanta 8, 579 (1961). (12) Bowersox, D. F., Smith, D. M., Swift, E. H., Zbid., 2, 142 (1959). (13) Zbid., 3, 282 (1960). (14) Broadhead, K. G., Heady, H. H., ANAL. CHEM.32, 1603 (1960). (15) Busev, A. I., Tiptsova, V. G.,
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I
tion," Vol. 1, Chaps. 1, 6, Interscience, New York, 1960. (99) Ross, H. H., Hahn, R. B., ANAL. CHEM.32, 1690 (1960). (100) Ryan, D. E., Can. J. Chem. 38, 2488 (1960). (101) Ryan, D. E., Lutwick, G. D., Zbid., 31, 9 (1953). (102) Salaria, G. B. S., 2. anal. Chem. 180, 358 (1961). (103) Salesin, E. D., Gordon, L., Talanta 5 , 81 (1960). (104) Salyer, D., Sweet, T. R., ANAL. CHEM.32, 548 (1960). (105) Sant, B. R., Beamish, F. E., Zbid., 33, 304 (1961). (106) Sant, B. R., Chow, A,, Beamish, F. E., Ibid., 33,1257 (1961). (107) Sant, S. B., Sant, B. R., Zbid., 32, 379 (1960). (108) Sant, S. B., Sant, B. R., Anal. Chim. ilcta 21, 221 (1959). (109) Sazonova, V. A., Leonov, V. N., Zhur. Anal. Khim. 14,483 (1959). (110) Schaffer, G. W.,Waller, M. C., Hohnsted, L. F., ANAL. CHEM. 33, 1719 (1961). (111) Schulek, E., Endroi-Havas, A., 2. anal. Chem. 174, 90 (1960). (112) Schwartzenbach, G., Geir, G., Helu. Chin. Acta 44, 859 (1961). (113) Selleri. R.. Caldini,, 0.., A4NAL. CHEM.33,'1944'(1961). (114) Shome, S. C., Analyst 75,27 (1950). (115) Sinha, S. K., Shome, S. C., Anal. Chim. Acta 21, 415 (1959). (116) Ibid., p. 459. (117) Zbid., 24, 33 (1961). (1181 Smvthe. L. E.. Whittem, R. N., Analyst 86, '83 (l96i). (119) Sotnikov, V. S., Alimarin, I. P., Talanta 8, 588 (1961). (120) . , Szabadvhrv. F., Takhcs, J., Erdey, L., 2. anal. Chi&. 1'82, 88 (1960). (121) Taimni, I. K., Salaria, G. B. S., Anal. Chim. Acta 11, 329 (1954). (122) Takiyama, K., Salesin, E. D., Gordon, L., Talanta 5, 231 (1960). (123) Tandon, S. C., Bhattacharya, S.c., ANAL.CHEM. 32, i94 (1960). (124) Tertipis, G. G., Beamish, F. E., Ibid.. 32. 486 (1960). (125) Uno,' T., 'Akihkma, S., J . Pharm. SOC.Japan 80, 1015 (1960). (126) Van Tassel, J. H., Wendlandt, W. W., Sturm, E., J . Am. Chem. SOC.83, 810 (1961): (127) Waterbury, G. R., Douglas, R. M., Metz, C. F., ANAL. CHEM. 33, 1018 (1961). (128) Wendlandt, W. W., Zbid., 32, 848 (1960). (129) Wendlandt. W. W.,' Anal. Chim. Acta 21, 116 (1959). (130) Wendlandt, W. W., Ewing, G. W., Ihid.. 22.497 (1960). (131) Wendlandt, W. W., Hoffman, W. M., ANAL.CHEM.32, 1011 (1960). (132) Westland, A. D., Westland, L., Talanta 3, 364 (1960). (133) Zieeler. M.. Z. anal. Chem. 180. . l(1960. ' ' (134) Ziegler, M., Gieseler, M., Zbid., 180, 415 (1961). ~
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Titrimetric (135) ilbel, G. J., ANAL. CHEM.32, 1886 (iRe,n). (136) Aikens, D. A., Schmuckler, G., Sadek, F. S., Reilley, C. N., Zbid., 33, 1664 (1961). (137) Ashbrook, A. W., Ritcey, G. M., Analyst 86, 740 (1961). (138) BAnyai, E., Gere, E. B., Erdey, L., Talanta 4, 133 (1960). (139) Barakat, M. Z., Abdalla, A,, Analyst 8 5 , 288 (1960). (140) Beck, M. T., Seres, I., Chemist Analyst 50, 14, 48 (1961). \ - - - - I -
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(141) Belcher, R., Rees, D. I., Stephen, (182) Higginson, W. C. E., Rosseinsky, W. I., Talanta 4, 78 (1960). D. R., Stead, J. B., Sykes, A. G., (142) Berndt, W., Sara, J., Ibid., 5, 281 Discussions Faraday SOC.29, 49 (1960). (1960). (183) Iwamoto, T., Bull. Chem. SOC. (143) Bishop, E., Anal. Chim. Acta 22, Japan 34, 605 (1961). 205 (1960). (184) Janougek, I., Studlar, K., Collection (144) Bishop, J. A., Zbid., 22, 221 (1960). Czechoslov. Chem. Communs. 24, 3799 (145) Bobtelsky, M., Carmon, B., Ibid., (1959). 21, 515 (1959). (185) Jones, S. L., Anal. Chim. Acta 21, 532 (1959). (146) Bobtelsky, M., Cohen, M. M., Ibid., 22,485, 532 (1960). (186) Joussot-Dubien, J., Oster, G., Bull. (147) Ibid., 23, 42 (1960). soc. chim. France 1960, 343. (148) Burger, K., Gaizer, F., Schulek, E., (187) Kakabadse, G., Wilson, H. J., Talanta 5, 97 (1960). Analyst 86, 402 (1961). (149) Burns, E. A., Muraca, R. F., ANAL. (188) Kennedy, J. H., ANAL. CHEM.32, 150 (1960). CHEM.32, 1316 (1960). (150) Busev, A. I., Chan, F., Zhur. Anal. (189) Kopanica, M., Pfibil, R., Collection Khina. 14, 445 (1959). Czechoslov. Chem. Communs. 25, 2230 cisfin). (151) Cameron, A. J., Gibson, N. A., \----/. Anal. Chim. Acta 25, 24, 429 (1961). (190) Kristiansen, H., Anal. Chim. Acta (152) Ceausescu, D., 2. anal. Chem. 183, 25, 513 (1961). 39 (1961). (191) Lassner, E., Puschel, R., Scharf, R., (153) Cheng, K. L., ANAL. CHEM. 33, Z. anal. Chem. 170, 412 (1959). 761 (1961). (192) Lassner, E., Scharf, R., Chemist (154) Ibid., p. 783. Anal@ 50, 6 (1901). (155) Clark, J. D., Smith, J. R., Ibid., 33, (193) Lassner, E., Scharf, R., Talanta 7, 1186 (1961). 12 (1960). (156) Close, R. A,, West, T. S., Talanta (194) Lassner. E., Scharf, R., 2. anal. Chem. 183, 187 (1961). 5, 221 (1960). (157) Davis, D. G., Jacobsen, W. R., (195) Lewis, L. L., Melnick, L. M., ANAL.CHEM.32, 215 (1960). S N A L . CHEM. 32, 38 (1960). (158) De Sousa, 8., Anal. Chim. Acta (196) Lindstrom, F., Diehl, H., Zbid., 32, 22, 522 (1960). 1123 (1960). (159) De Sousa, .4.,Talanta 8, 686, 782 (197) Luke, C. L Ibid., 33, 96 (1961). (1961). (198) Ibid., p. 13$5. (100) De Sousa, A., 2. anal. Chem. 174, (199) McCurdy, W. H., Jr., Guilbault, 837 11960). G. G., Ibid., 32, 647 (1960). (101) Diehl,' H., Ellingboe, J., .INAL.(200) Manning, D. I,., Menis, O., Talanta CHEM.32, 1120 (1960). 6, 30 (1960). (102) Diehl, H., Smith, G. F., Talanta (201) Margerum, D. W., Bydalek, T. J., 2, 382 (1959). Bishop, J. J., J . Am. Chem. SOC.83, 1791 (1961). (163) Dubsky, I., Collection Czechoslov. Chem. Communs. 24, 4045 (1959). (202) Mee, J. E., Corbett, J. D., Chemist (164) Duke, F. R., ANAL.CHEM.31, 527 Analyst 50, 74 (1961). (1959). (203) Middleton, K. R., Analyst 86, 111 (165) Eggers, J. H., Talanta 4, 38 (1960). (1961). (166) Endo, Y., Takagi, H., Japan (204) illohr, E., Chem. Tech. (Berlin) 11, Analyst 8, 829 (1959). 598 (1959). (167) Erdev. L.. Buz& I.. Anal. Chim. (205) Murty, B. V. S. R., Rao, G. G., Acta 22."624 (1960). ' Talanta 8, 438 (1961). (168) Erdky, L.; Gere, E. B., B h y a i , E., (206) Mustafin, I. S., Kruchkova, E. S., Talanta 3, 209 (1959). Zhur. Anal. Khim. 15,20 (1960). (169) Erdey, L., InczBdy, J., Markovits, (207) Numajiri, G., Kodama, M., J . I., Ibid., 4, 25 (1960). Chem. SOC.Japan, Pure Chem. Sec. 81, (170) Erdey, L., Vigh, K., Pdos, L., 454 (1960'1. Ibid.. 3. 1 (1959). (208) Nydahl, F., Talanta 4, 141 (1960). (171) Fabregas, R:, Badrinas, A., Prieto, (209) Olsen, R. L., Diehl, H., Collins, A., Ibid., 8, 804 (1961). P. F., Ellestead, R. B., Ibid., 7, 187 (172) Fauth, M. T., McNerney, C. F., (1961). ANAL. CHEM.32, 91 (1960). (210) PaleI, P. N., Chang, W-C., Zhur. (173) Flaschka, H., Ganchoff, J., Talanta Anal. Khim. 15. 598 (1960). 8, 720 (1961). (211) Povondra, P., Piibil, R., Collection (174) Ibid., p. 885. Czechoslov. Chem. Communs. 26, 311 (175) Fritz, J. S., Abbink, J. E., Payne, (1961). i\l. A., ANAL.CHEM.33, 1381 (1961). (212) Powell, J. E., Fritz, J. S., James, (176) Fritz, J. S., Pietrzyk, D. J., Talanta D. B., ANAL.CHEM.32. 954 (1960). 8, 143 (1961). (213) Ptibil, R., Talanta 3,'91 (1959). ' (177) Geyer, R., Chojnacki, K., Z. anal. (214) Zbid., p. 200. Chem. 179, 409 (1961). (215)1Pfibil, R., Burger, K., Zbid., 4, 8 (178) Goryushina, V. G., Archakova, T. (1960). A., Zavodskaya Lab. 25, 789 (1959). (216) Pfibil, R., Vesely, V., Ibid., 8, 565 (179) Grant, D., Payne, D. S., Anal. (1961). Chim. Acta 25, 422 (1961). (2i7) Ibid., p. 743. (180) Guilbault, G. G., McCurdy, W. H., (218) Ibid., p. 880. Jr., ANAL. CHEW33, 580 (1961). (181) Guilbault, G. G., McCurdv, W. H..' (219) PIibil, R.. Veselv. V..' Kratochivii, Jr., Anal. C h h . Acia 24, 214-(1961). . K.', Zbid., 8, 52 (196l").' \ - - - - ,
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(220) Puschel, R., Lassner, E., Chemist Analyst 50, 26 (1961). (221) Reilley, C. N., Flaschka, H. A., Laurent, S., Laurent, B., ANAL.CHEM. 32, 1218 (1960). (222) Sachse, H. B., Ibid., 32, 529 (1960). (223) Sant, B. R., Sant, S. B., Talanta 3, 261 (1960). (224) Sastrv. T. P.. Pratt. S. A.. Z. anal. ' Chem. 175; 182 (1960). ' (225) Schulek, E., Barcza, L., Talanta 3, 23, 27 (1959). (226) Schulek, E., Burger, K., Laszlovszky, J., Ibid., 7, 51 (1960). (227) Schwartzenbach. G.. ANAL. CHEhf. ' 32. 6 (1960). (228j Siribne;, W. G., Ibid., 32, 966, 970 (1960). (229) Scribner, W. G., Anduae, R. A, Ihid., 33, 770 (1961). 1230) Seal. K. C.. Anal. Chim. Acta 24. 536 (1961). (231) Sen Sarma, R. X., A N A L . CHEST. 32, 717 (1960). (232) Sporek, K. F., Zbid., 30,1032 (1958). (233) Stockdale, D., Analyst 84, 667 (1959). (234) Strahm, R. D., Hawthorne, M. F., ANAL.CHEM.32, 530 (1960). (235) Svoboda, V., Talanta 4, 201 (1960). (236) Svoboda, V., Chromy, V., Korbl, J., Dorazil, L., Ibid., 8, 249 (1961). (237) Svoboda, V., Dorazil, V., Korbl, J., Collection Czechoslov. Chem. Communs. 25, 1037 (1960). (238) Takahashi, I. T., Robinson, R. J., ANAL. CHEM?. 32, 1350 (1960). (239) Turowska, M., Chem. Anal. (Warsaw) 5, 815 (1960). (240) Tyniec, T., Ibid., 5, 775 (1960). (241) Underwood, 9. L., ANAL. CHE\I. 33. 955 (1961). ( 2 i 2 j Underwood, E. A., Underwood, A. L., Talanta 3, 249 (1960). (243) Verbitskaya, T. D., Romanova, N. K., Zavodskaua Lab. 26, 818 (1960). (244) Verma, M. "R., Agarwal, K. C., J . Sci. & Ind. Research (India) 19B, 319 (1960). (245) Volf, L. A., Zavodskaya Lab. 26, 1353 (1960). (246) Wagner, F., Z. anal. Chem. 178, 34 (1960). (247) Wanninen, E., Talanta 8, 355 (1961). (248) Watts, H. L., ANAL. CHEM. 32, 1189 (1960). (249) West, T. S., Anal. Chim. Acta 25, 301 (1961). (250) Wilkins, D. H., Ibid., 23,309 (1960). (251) Wilkins, D. H., Talanta4, SO (1960). (252) Ibid., p. 182. (253) Wilkins, D. H., Hibbs, L. E., Ibid., 2 , 201 (1959). (254) Wilkins. D. H.. Smith. G. E.. Ibid., ' 8,'138 (1961). (255) Wolf, L., Franz, H., Hennig, -. H., 2. ' Chem. 1,'27 (1960).' (256) Wronski, pvl., 2. anal. Chem. 179, 350 (1961). (257) Yamamura, S. S., Kussy, M. E., Rein, J. E., ANAL. CHEM. 33, 1655 (1961). (258) Zvenigorodskaya, V. M., Ryanicheva, M. I., Zhur. Anal. Khim. 14,457 (1959). I
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