ANALYTICAL CHEMISTRY Proskuryakora. G. F., Zacodsknuu I,&., 16, 364-5 (1950). Pshenitsyn, S . K . , Izrest. Sektora Platin!! 1‘ Drugilch Blngorod Metal., Inst. Obshchei I . Scorg. I i h i m . A k a d . , S a u k . S.S.S.R., S O .22, 7-15 (1948). Ibid., pp. 16-21, Pshenitsvn. S.IC.. and Fedorov. I. A . . Ibid.. S o . 22.76-9 (1948). Pshenitsyn, T.K., Fedorov, I. A , , and Simanorakiy, P. V., Ibid., KO. 22, 22--7 (1948). Pshenitsyn, N. K., and Ginzburg, S. I., Ibid., N o . 22, 136-44 (1948). Ibid., KO.24, 118-20 (1949). Pshenitsyn, K . K., Ginzburg, S . I., and Yal’skaya, L. G . . Ibid., TO.22, 64-75 (1948). Pshenitsyn, S . K.. and Gladyshevskaya, K. A,, Ibid., T o . 22, 60-3 (1948). Pshenitsyn, N. K., and Lazareva, M.V., Ibid., No. 22, 49-59 (1948). Pshenitsyn, S . K., and I’akovleva, E. A , , Ibid., KO. 22, 43-48 (1948). Puroshottam. A . , and liao, Bh. 9. V. R., Analyst, 75, 555-7 (1950). Ibid., pp. 684-6. Quadrat, O., and Svejda, Z., Chem. Obzor, 25,85-7 (1950). Rafter, T. A , A n n l y s t , 75, 485592 (1950). Rao, B. R.,and Rao, Bh. S.V. R., J . I n d i a n Chem. Soc., 27, 467-8 (1950). Rasmussen, S.W., and Rodden, C. J., “Analytical Chemistiyof the Manhattan Project,” pp. 459-82, New York, McCrawHill Book Co., 1950. Rby, Priyadaranjan, and Bhaduri, Ajitsankar, J . I n d i a n Cheni. SOC.,27, 297-304 (1950). Rodden, C. J., and Karf, J. C., “Analytical Chemistry of the Manhattan Project,” pp. 1-159, New York, McGraw-Hill Book Co., 1950. Sapir, A. D., Zaroddkaya Lab., 16, 494 (1950). Sarudi, Imre, 2. anal. Chem., 130, 301-3 (1950). Ibid.. 131. 416-23 11950). Ibid., pp. ’424-6. Seelyo, F. T., and Rafter, T. A., Xafure, 165, 317 (1950) Seguin, M . , and Gramme, I,., Bull. SOC. chim. France, 1950, 375-84. Seliverstov, K. S., Izrest. Scktora Platiny i Drugikh B l n g o i o d Metal, I n s t . Obshchei i IVeorg. Khim. Akad., S a u k . S.S.S.R., KO. 22, 80-94 (1948). Serebrennikor, V. V., C’chenye Z a p i s k i Tomsk., Gosiidomt Cniz.. im. S.V . Kuibysheca, 1948, S o . 8 , 111-23. ~
Shell, H. R., A K ~ LCHEV., . 22, 575-7 (1950). Steinle, Heins, Z.annl. Chcnc., 129, 340-5 (1949). Tarasevich, K, I., Vestnik M o s k o ~ rnia., 3, N o . 10, 161-8 (1948). Temuleton. D. H.. and Bassett L. G.. “hnalvtical Cheniistrv of the Manhattan Project,” pp. 321-38, S e w York, McGran:Hlll Book Co.. 1950. Tinovskaya, E. S.,Zhzcr. Anal. Khzm., 5, 345-53 (1950). Ubaldini, I., Proc. X I t h Intern. Congr. Pure and Applied Chenr. ( L o n d o n ) , 1, 293-5 (1947). U. S. Atomic Energy Commission, “Manual of Analytical Methods for the Determination of Cranium and Thorium in Their Ores,” Kashington. Gorernnient Printing Office, 1950. Valentin, F., and Suchhrori, Ai., Chem. Zvesti, 4, 68-80 (1950). Venkataramaniah, II.,and Rao. Bh. Y. T’. R., d n o l i p t , 75,. 553-4 (1950). Ibid., 76, 107-9 (1951). Venkataramaniah, RI., and Rao, Bh. S. V. R., J . I n d i a n Chem. Soc., 26, 487-9 (1950). Venkataramaniah, XI., Satyanara~anamurt~iy, T . K., and Rao, Bh. S. V . R., Ibid., 27, 81-6 (1950). T’enkateswarlu, Ch., and Rao, Bh. S. V, R., Ibid., 27, 395-6 (1950). Visman, J., Fuel, 29, KO.5, 101-5 (1950). Vo?iSek, J., and T’ejdslek, Z., Chem. Listy, 37,50-3, 65-70, 91-5 (1943). Voter, R. C., Banks, C. Y.,and Diehl, H., ANLL. CHEY., 20, 458-9 (1948). Ware, E., U. S.Atomic Energy Commission, Rept. MDDC-1432 (August 1945). Wenger, P. E., hionnier. D., and Besso, Z., S n a l . Chini. A d a , 3, 660-2 (1949). West, P. IT.,and Conrad, L. J.. Ibid., 4, 561-5 (1950). Westwood, W,, Brit. Cast I r o n Research Assoc. J . Research & Del;eZo?jment,3 , 377-80 (1950). Westwood, W,, and Presser, R., Ibid., 3, 515-19 (1950). Wilcox, L. V., IND.ENG.(:HEM., ANAL.ED.,9, 136-8 (1937). Willard, H. H., and Sheldon, J. L., ANAL. CHEM.,22, 1162-6 (1950). Yarne, J. I,., and Sobers, W .R., Am, Faundryman, 17, S o . 6 , 33-5 (1950). Young, R.S., A n a l . Chini. Acta, 4, 366-85 (19501. Zhivopistsev, V. P.. D o k l a d ~d k a d . S n i t k . S.S.S.R., 73, 1193-6 (1950). KECE1VE.D October 19
1031
Inorganic Volumetric Analysis CLEMENT J . RODDEN AND CLARA GALE GOLDBECK C’. S. A t o m i c Energy C o m m i s s i o n , New Brunswick, .V. J .
T
HIS review covers the years 1950 and 1951 and follows the pattern of previous reviews. T h e trend toward instrumental methods has been quite pronounced in t,he past feiv years, with the result t,hat developments in direct volumetric methods have been decreasing to a noticeable extent. BOOKS AND REVIEUS
&-edited methods for ferrous and nonferrous metals by the hinerican Society for Testing Materials (2) have brought this useful volume u p t o date. Books and pamphlets on the assay of uranium include one containing a review of methods used on the Manhattan Project (186), a handbook of met,hods in use in England ( i o ) , and one in use in the United States (187). .1new edition of the well-knon n monograph on volumetric iodate methods has appeared (203) and a comprehensive review of sampling methods (56) was published. Reviews include those on fluorine ( 7 6 ) ;Kjeldahl nitrogen method as applied to microanalysis (123’); the determination of carbon dioxide from carbonates in agricultural and biological material ( 2 2 7 ) ; and the determination of chlorine in water (106). Reviews on the Karl Fischer method for water have included comparison and preparation of reagents and methods of determinations (114), a round table review discussion
(150), and applications to determination of water in mirrerals (119). STUDIES O F \lETHODS
Studies of titration in glacial acetic acid have shown t h a t salts of strong bases and tveak acids, weak bases and weak acids, and \veak organic bases can be titrated using perchloric acid as a titrating agent (142). The relative merits of ceriometry and vanadiometry have been studied and ammonium vanadate is stated to have certain advantages (632). LIanganese sulfate is stated to have certain advantages over iodine muiiocahloride as a catalyst in ceric sulfate titrations (239). Factors affecting the stability of ferrate(V1) ion in aqueous solutions have been studied to improve the use of the reagent as an oxidizing agent in alkaline solutions (195). During titrations in neutralization reactions the change in volume and also heat of t h e reaction has an effect on the pH of the solution. Changes in internal resistance are indicated (193). A P P 4 R 4TL S
Considerable interebt has been shorn 11 in the development of instruments for high frequency titrations. Of the various instruments described ( 5 , 21, 23,92),the stable high frequency titriin-
V O L U M E 24, N O . 1, J A N U A R Y 1 9 5 2 eter j23) and the impedance measuring circuit made from commercially available parts ( 9 2 ) appear quite satisfactory, A highfrequency apparatus from Japan (157) and the radio-frequency apparatus for conductometric titrations (26-28) are of considerable interest. The radio-frequency equipment can be used for microtitrations. A simple apparatus for microconductometric titrations of volumes less than 1 ml. has been described (208). Improvements in apparatus for the Karl Fischer titrator have been in a microburet (243)and a magic-eye indicator (120). A dark rhamber for use in a chemiluminescent indicator titration u i t h highly colored solutions has been described (119). A cell for photometric titration has been made ( 8 7 ) . Construction and details have been given (111) for an inexpensive recording autotitrator. Modifications of volume measuring equipments have included a platinum tip for a microburet ( 4 2 ) ; a constant-flow buret based on a Mariotte-flask principle (225); a 1-ml. buret made from a pipet ( 2 0 9 ) ; a microburet ( 1 2 9 ) ; a buret for use with air-sensitive reagents ( 1 6 ) ; a combination buret and Jones reductor (65, 6 8 ) ; filling devices ( 9 1 ) ; a microburet-pipet combination (185); and a micropipet ( 3 2 ) . For microtitrations, a device for rotating the vessel has been described (210). STANDARDS ASD REAGENTS
A series of papers in Xetallurgia (162-164) has reviewed the subject of primary standards for various types of reactions, including acidimetry, oxidinietry, and argentometry. Potassium acid phthalate is recommended (199) as a standard for acidimetric titrations in glacial acetic acid. A color standard has been used for precision assay of potassium acid phthalate (57). The following have been suggested for use as acidimetric standards: hydroxyniethylaminomet,hane as a substitute for potassium acid phthalate ( 7 4 ) ; sulfaniic acid (100); and potassium iodate ( 9 , 166). An investigation has been made on the standardization of permanganate ( 5 5 ) , and a rapid method for making a standard permanganate solution (248) using kaolin has been proposed. Commercial analytical reagent potassium dichromate is shown ( f 3 7 )to be satisfactory as a standard. The standardization of titanium chloride solution with potassium dichromate (34) has been suggested as better than other methods. Manganese(II1) solutions can be preserved for a t least, 10 days (107)and chromous salts can be kept when in contact nith amalgamated zinc (15.4). The reductor buret was used for vanadium(I1) solutions (146). A study of the standardizationof hypochlorite solutions (133) shows Penot’s method with arsenite to be the most satisfactory. The use (216) and preparation (217) of periodate solution has been described and another method for preparing sodium thiosulfate has been given (240). A detailed desci,iption of volumetric standardization ( 4 ) , based on pure electrolytic silver as ultimate standard and with iodine, sodium carbonate, sodium chloride, arsenious oxide, and potassium dichrom a t e as working standards, is given by the Analytical Chemists Committee of Imperial Chemical Industries, Ltd. A study of the standardization of silver nitrate for the assay of cyanides has been made (103). In the Karl Fischer t,itratioii, sodium tartrate dihydrate is proposed as a primary standard (156). By adding starch and potassium iodide together (207), a more stable indicator solution is obtained. Silver peroxide is proposed as an oxidizing medium for cerium determinations (182). DETERMISATIONS B Y ELEMENTS
Acids. Mixtures of two weak acids were determined tip conductance tit,ration using empirical conditions and formulas (194). Free acids were determined in antimony and bismuth salt solutions by precipitating with potassium ferrocyanide, filtering, and titrating with sodium hydroxide (170). Potassium oxalate is used to complex aluminum in determining free acid in aluminum nitrate (2%). In a novel method, sulfuric acid is precipitated ill
103 aniline and, after filtering and dissolving, is titrated with sodium hydroxide (169). For traces of sulfuric acid in the air, collection on filter paper is used, followed by titration as usual (141). Aluminum. Variations of the fluoride method were: using lithium chloride in a routine control method ( 8 6 ) ; saturating the solution with sodium chloride in ethyl alcohol prior to titration (184);and using barium hydroxide and barium salts prior to addition of the potassium fluoride (231). Antimony. Low’s permanganate method is used in the analysis of bearing metals (181). Antimony is determined together with arsenic by titration with potassium bromate (173). A modification of the method of Gyory is given in which complete decomposition of hydrogen peroxide, used for alloy solution, is ensured by decomposition with sodium sulfite, followed by reduction with sulfur dioxide and titration with potassium bromate using methyl red as an indicator ( 1 9 ) . Arsenic. Arsenic is determined iodometrically in the eluate from an ion exchange column which separates oxidized arsenic from interfering elements (165). A simplified distillation apparatus for separat>ionof arsenic is described and the addition of phosphoric acid is recommended in a potassium bromate titration with methyl red indicator which is decolorized a t the end point (15). In mixtures of arsenicand antimony, arsenicis titrated preferentially by potassium bromate in the presence of iodine monochloride. Too much sulfuric acid interferes and should be neutralized (173). Arsenic is determined in iron, steel, and iron ores by addition of copper sulfate to the solution, reducing the arsenic with sodium hypophosphate, and filtering. Excess standard iodine solution is added to the filtrate and the excess is titrated with 0.03 Y sodium thiosulfate using starch as indicator (115). Barium. Standard sulfuric acid is added to an aqueous solution, followed by titration of excess acid with sodium hydroxide
(64). Beryllium. T h e high-frequency titrimeter was used for titrating an essentially pure solution of beryllium with sodium hydroxide ( 5 ) . Boron. Boron in electroplat.ing baths (247) and magnesite ( 9 9 ) was determined by the usual volumetric method employing mannitol after removing metals. Metal borides are fused with sodium carbonate and, after dissolving and filtering, titrated with sodium hydroxide as usual ( 3 0 ) . I n a rapid method, sodium carbonate replaces the usual sodium hydroxide (154). Bromine. .4study ( 6 ) of bromonietric titration reports on the development of an apparatus which eliminates bromine losses due t o evaporation, uses titration with sodium and potassium thiosulfates, and gives an iodometric end point for titration of bromine. I n a comparison study ( 9 8 ) )the method of Kolthoff and 1-utzy, in which the bromide is oxidized with sodium hypochlorite, was found most satisfactory. I t s application to mixtures of chlorides and bromides is described (97). Compared with it is an electrolytic method of oxidation, and the aeration method of Evans in which chromic acid v a s found to be a more selective oxidizing agent than sulfuric-chromic acid (98). In the determination of bromine ion, most interferences can be removed by sodium carbonate treatment. Bromine can also be distilled into alkaline hydroxide after treatment with potassium permanganate. A thiosulfate titration is made following the addition of chlorine and potassium iodide (220). . I n Meulen’s method .of oxidation with potassium oxychloride the pH should be kept between 6 and 7 and addition of sodium chloride should be omitted (180). Bromine can be determined in the presence of large amounts of chloride and iodide by removing iodine following addition of ferric ammonium sulfate and titrating with chlorine water in slightly acid solution (222). Cadmium. A rapid iodometric method which has several interfering ions has been proposed ( 3 ) .
104 Calcium. The high-frequency titrimeter has been used for titrating calcium with a soap solution but magnesium interferes (113). Variations of the time-honored oxalate-permanganate method have been reported for potassium minerals (1 ) in the presence of nickel and cobalt (81), in dolomites and slags (254),when using acetic acid (235), and after first separating with oxine followed by a n oxalate precipitation (290). Calcium can also be separated with potassium ferrocyanide and the precipitate titrated n-ith permanganate (10, 71) or ceric sulfate (72). Versene has been used for the analysis of leaf tissue (245). By usinR a 0.1 N solution of hexanitrodiphenylamine, calcium can be determined volumetrically but phosphate, carbonate, and ammonium ions interfere (75). Carbonate. Several methods are enumerated for the determinat,ion of carbonate in agricultural and biological materials. These are most,ly modifications of titrimetric methods in which carbon dioxide is absorbed in standard alkali solutions and titrated with acid (227). Carbonates are determined in the presence of bromine and chlorine by reducing the halogens with ferrous sulfate and sodium arsenite, boiling out the carbon dioxide into an alkaline solution, and titrating (97). Cerium. A "silver peroxide" has been used in t,he oxidation of cerium n-hich is more efficient than persulfate and silver ion (222). Chlorine. Alkali halides and amine hydrochlorides can be titrated with perchloric acid in glacial acetic acid (101). By masking the premature blue color, the mercuric nitrate-diphenyl carbazone titration n-as improved (46, 47). Modification of the Volhard method was applied to inorganic salts after liberating chlorine with manganese dioxide and absorbing in sodium carbonate and peroxide (11 2 ) ; to iodates after precipitation as bariumio date (206); and to bromine-containing substanceg (197). If the ferric ion concentration is made 0.2 volume formal, Volhard end points are stable (213). A review of methods for chlorine in water showed the iodometric and methyl orange titration methods tu be satisfactory (105). In a rapid method for hypochlorite, pot'assium iodide is used as titrant (168). I n the Berg method, accuracy is improved by keeping the acid concentration xithin certain limits (638). The direct titration with mercuric nitrate using high-frequency titration appears superior to the potentiometric or conductometric method (22). Chromium. I n alkaline solutions, potassium ferrate has been used to oxidize Cr(II1) (191). T'ariations of the ferrous sulfatepermanganate titration for chrome ore (ZOO), synthet,ic samples ( 9 4 ) , and in the presence of vanadium ( 7 8 ) and steel ( 11 0 ) have been made. For cast iron and steel, a modification of the bromate oxidat,ion proved highly satisfactory (96). An iodometric method for a mixture of permanganate and dichromate employing reduction of permanganate with ethyl alcohol has been proposed ( 8 3 ) . Cobalt. I n a n iodometric method the carbonate complex of Co(II1) is reacted with iodide to form iodine ( 1 3 2 ) . By adding excess ferricyanide to a solution, cobalt can be determined after back-titrating with standard cobalt sulfate (229). Columbium. A study of the reduction with zinc amalgam followed by permanganate titration has been made (127). Copper. Several procedures are reported n-hich use iodometric titrations ( 7 , 35, 181). I n one instance sulfide ores are oxidized with perchloric acid and complesed with fluoride before the iodometric titration ( 8 9 ) . Two methods are reported for titration with potassium permanganate of the ferrous ion that results from the oxidation of cuprous oxide (241)or cuprous sulfide (172). I n the bromometric titration of hydrazine following the precipitation of copper with hydrazine sulfate, fuchsin, tropeolin 00, or thymol blue are recommended as indicators (17 7 ) . A new method is reported in which copper thiocyanate is pre-
ANALYTICAL CHEMISTRY cipitated with pyridine and ammonium thiocyanate, and the escess thiocyanate is titrated with silver nitrate ( 167). Cyanide. A silver nitrate titration can be performed in a photoelectric colorimeter or turbidimeter in the presence of ammonia and pot,assium iodide (13). Nickel ammonium sulfate can be used to titrate cyanide using dimethyl glyoxime as indicator (233). It is recommended t h a t the silver nitrate solution used for titrating cyanides be standardized by t'he Volhard method (103). Ferrocyanide. I n a variation of a standard procedure, potassium ferrocyanide is determined by titration with zinc sulfate, with ferric chloride as outside indicator, and without potassium chloride added ( 102). Sodium vanadate with diphenylbenzidine as indicator can be used to titrate solutions which are not more than 0.0166 N in ferrocyanide and are over 1 N in H + ( 179). Results are reported t o be as accurate as with potassium permanganate and can take place in the presence of hydrochloric acid and oxalic acid. Fluorine. A photofluorometric method using thorium nitrate and quercetin as fluorescent indicator has been proposed (244). The method of Willard and Winter has been discussed ( 8 , 8 6 ) and a simplification applied to agricultural substances (84). T h e back-titration method has not proved as fast (202) as the saltacid method of Williams. By titrating in a 50% alcohol system using gallocyanine as an indicator, usual errors may be avoided (183). A modification of the lead bromofluoride method has been applied to the analysis of welding flux (45). Germanium. Germanium dioxide reacts with mannitol to form a strong complex acid which can be titrated with sodium hydroxide (48). Iodine. Iodine in thallium salts is determined by reducing t h e thallium t o the metallic state with zinc and titrating t,he iodide potentiometrically with silver nitrate (126). A means of improving' the accuracy of mercurimetric titration with dithizone indicator is suggested ($80). Permanganate titrations are carried out in the presence of sulfuric acid and acetone, a complex being formed (43). Iodometric titrations are made following oxidation to the iodate by chlorine water (180, 222). Free iodine is determined in the presence of iodides by titration with alkaline arsenious oxide solutions and then total iodine is determined after addiing potassium iodate and again titrating with arsenious oxide (82). Iridium. .4fter oxidizing, the sample is titrated with hydroquinone or potassium ferrocyanide using o-dianisidine as an indicat,or (146). Iron. Lletallic iron is determined in the presence of its oxides by dissolving with bromine in alcoholic solution and filtering. Iron from both oxide and metal is determined by the Zimmermann-Reinhard method and Fe +2 is determined by permanganate (237). Metallic iron in ores is also determined by permanganate titration following solution with copper sulfate (205). Direct titrations of ferric iron include those iTith mercurous nitrate ( 6 7 , 236), with stannous chloride (196),with a double indicator of thiocyanate and ammonium molybdate ( @ I ) ,and with titanous chloride (11, 69). I n another method, the sample is dissolved in a solution containing ammonium vanadate, and the unreduced vanadate is titrated with Mohr's salt (109). Ti+3 is also used to titrate iron hydrosyquinolate (10). Ascorbic acid is used to titrate Fe'3. ( 7 3 )and i t is also added in excess and back-titrated indnmetrically (176). Methods involving reduction of iron followed by titration employ potassium dichromate (37, 160) and ceric sulfate (196), the. latter in the presence of ethyl alcohol and acetaldehyde (224),and in a micromethod ( 6 6 )following reduction with zinc amalgam. I n a modification of Densen's method, an improved decom-position chamber is described and direct permanganate tit'ration. is replaced by an indirect titration (96).
VOLUME
2 4 , NO. 1, J A N U A R Y 1 9 5 2
Representative volumetric methods are given on a seniirnicro scale (189). Lead. .As an indicator in the titration of lead with molybdate, potassium cyanate and stannous chloride are used, which form 4H20 (131). Precipit,ation as oxalate the red Ka[?rIo(CNS)e]. followed by oxidimetric titration of the oxalate is stated to be more precise than the chromate-iodometric method ( 6 4 ) . For ores and concentration products the chromate method is used ( 6 0 ) . Lead oxide in the presence of lead is determined by heating with ammonium chloride and titrating t,he ammonia liberated (20). Magnesium. Magnesium in leaf tissue has been determined using 1-ersene (245). High-frequency titrations with soap solutions have proved satisfactory in the absence of calcium (113). Oxine precipitation followed by bromide t,itrat,ionhas been used after a ferrocyanide separation (10). Oxine has also been used as a final separation for magnesium in cast iron (44). An arsenatecerimetric method has been proposed (144). Adapt'ations of the magnesium ammonium phosphate method have been made for rapid methods in dolomite and slags (234), potassium minerals ( l ) ,and agricultural products ( 9 3 ) . Manganese. Manganese can be determined in strong alkaline solutions by titrating with pot,assium ferrocyanide in t,he presence of ammonium carbonate and potassium cyanide (219). A study of the ferrocyanide method showing effects of interfering elements has been made (174). When oxidizing manganese with persulfate, silver consumption can be cut by proper attention to acid concentration (61). h4anganese in a mixture of permanganate was determined b y adding potassium iodide, titrating, adding ethyl alcohol, filtering off the manganese, and then titrating the chromium iodometrically ( 8 9 ) . K i t h acetylacetone manganese ions form a stable complex which has no action on potassium iodide, while under the same conditions tetravalent manganese c-hloride loses chlorine with aretylacctone which liberates iodine from potassium iodide (79). Mercury. Trarcs of mercury are distilled and determined by a dithizone titration (148). Mercuric ion reacts with acetone to give hydrogen ion n-hich can be titrated Tvith alkalies ( 6 2 ) . A method similar to that of S-olhard for silver is applicable to mixtures of niei~curousand mercuric ion (36, 58). Nitrogen. S i t r i t c is reduced ivith zinc powder and sodium carhonat?. The ammonium formed is titrated in the usual manner (106'). h critical kurvey of the methods for nitrates has resulted in one in which the nitrate is reacted with permanganate and iodide, and the liberated iodine is titrated ( 3 3 ) . By absorbing in sulfuric acid, nitric oxide and nitrogen tetroxide may be determined by analyzing for total nitrogen xvith a nitrometer and for nitrosyl nitrogen by permanganate titration (,QZ). A review of micro Kjeldahl methods has been made ( 2 9 ) and nickel sulfate is proposed as an absorbent. Aluminum nitride in steel is determined by reacting with an ester-halogen solution, removing the aluminum nitride by filtration and then using the Kjeldahl method ( 1 2 ) . Oxygen. Ozone in high concentrat,ion has been absorbed in potassiuni iodide and the iodine liberated is titrated with thiosulfate (31). For dissolved oxygen, the sample is added to standard chromous chloride and excess chromous ion determined by adding potassium iodate and titrating with chromous ion; the apparatus is described ( 2 1 2 ) . For determining oxygen in metal oxides, the oxide is reacted with sulfur and the liberated sulfur dioxide is determined iodometrically ( 5 8 ) . Palladium. Organic compounds, especially furfural diosinie, were used to precipitate palladium, which was then treated with vanadyl sulfate and the excess titrated with ferrous sulfate (215). I n another method, after precipitating as chloropalladate, the precipitate is dissolved in standard ferrous sulfate and excess ferrous sulfate titrated (214). Phosphorus. After surveying methods for determining phos-
105 phate, a method was developed in which phosphate is precipitated as quinoline phosphomolybdate and the precipitate is titrated with standard hydrochloric acid (246). For iron ores, modifications of the ammonium phosphomolybdat,e method have been, used (117,118). Potassium. hiodifications of the cobalt nitrite method include titration with sulfuric acid (88' and with dichromate (108). Selenium. A control meti,od for metallic copper and pyritic material consists of distilling selenium as tetrabromide and after adding potassium cobalticyanide and potassium iodide, titrating with thiosulfate (140). A similar procedure precipitates selenium before the iodometric titration (158). By using pyrophosphoric acid as a complexing agent and iodine monochloride as a catalyst, a rapid method for selenium in the presence of tellurium has been developed (219). Silicon. A conductometric titration using lead nit.rate has been proposed (14). I n modifications of the fluorosilicate method, standard hydrochloric acid is added to the silica and potassium fluoride and the exceas acid is titrated with standard potassium hydroxide (192,198). Fluorosilicic acid has been determined by a method which is essentially t h a t of Scott and Furman (266). Silver. Silver is determined in the presence of lead and copper by adding i t to a blue starch-iodine solution in the presence of potassium iodide, causing the indicat,or t,o fade. Calibration of the method under similar conditions is required (39). Rapid determinations have been made by the addition of a measured volume of hydrochloric acid and titration of the excess with standard alkali (64). Ultramicro quantities were determined by two methods (228) -titration with 0.005 to 0.01 N ammonium thiocyanate using ferric ammonium sulfate as indicator and titration with the silver salt solution of an iodide solution with iodo-starch indicator. Sodium. -kIloys of sodium and aluminum are separated by vacuum distillation and the sodium is p r e c i p h t e d with zinc uranyl acetate. The uranium is then titrated using titanous chloride (135). Another indirect application of the zinc uranyl acetate method employs the lead reductor to reduce the uranium (139). I n the presence of antimony, the antimony is distilled as chloride and the sodium chloride left behind is titrated with silver nitrate (168). Sodium oxide in metallic sodium is determined by removing metallic sodium with mercury and titrating the oxide with hydrochloric acid (171). Strontium. For a rapid determination, precipitation with standard sulfuric followed by t,itration of excess acid has been used ( 5 4 ) . Sulfur. iZ photometric t,itration using lead nitrate and alcohol has been proposed for sulfate (223). I n another method for sulfate, barium iodate is used, followed by iodometric titration (204). Sulfate can also be determined by precipitating sulfate with barium, the excess barium then being titrated with Versene (162). By using stannous chloride, sulfate can be reduced to hydrogen sulfide, which can then be determined iodometrically (178). I n a rather complicated procedure involving fuming in hydrogen, sulfur is converted to hydrogen sulfide which is converted to polysulfide and titrated with hypochlorite (164). Sulfur is determined by boiling with standard sodium hydroxide and titrating the excess alkali (77). It has been stated t h a t for accurate results the usual iodometric method for determining sulfur in steel is not accurate. Alkaline hypochlorite is stated to have advantages (125). Polysulfides are dissolved in excess standard potassium iodide containing carbon disulfide. Plfter adding thiosulfate the excess is determined with standard iodine ( 6 1 ) . Complete procedures for commercial alkali polysulfides ( 9 0 ) m d sulfate, sulfide, and polysulfides have been given (191). Tellurium. The t,ellurium in metallic copper is separated with hypophosphite, dissolved wit,h bromine, and, after adding potassium cobalt,icyanide and sodium hypophosphite, titrated with iodine (158).
ANALYTICAL CHEMISTRY
106 Thallium. For small amounts, a dithizone separation followed by iodometric titration has been used in ores and flue dust (201 )) while for zinc-cadmium solutions an oxidation with bromine followed by iodometric titration has been used (121 ). Thorium. A review (59) of the general analytical chemistry of thorium contains some volumetric methods but since thorium has only one valence, indirect methods are used. A modification of the oxalate precipitation-permanganate method has been reported (143). A direct titration with sodium oxalate using the high-frequency titrimeter can be used (24). Tin. T h e lead reduction-iodometric procedure has been used for bearing metals (181), bronzes (169, 161), pig tin (116), and ores ( 5 2 ) . For cable sheathing alloys, after determining antimony, reduction with sodium hypophosphite, followed by iodometric titration, has been used (19). I n the usual method using nickel as reductant, it is shown that some tin is coprecipitated with the antimony (104). Titanium. Titanium(II1) has been oxidized with vanadium pentoside during solution and the excess vanadium is titrated a i t h ferrous ion (156). If acetic acid and ammonium sulfate are used, it is stated that titanium(II1) can be titrated without interference of oxygen of the air (218). Titanium is reduced with metallic iron and titrated with ferric ion (17, 18) in titaniurn-rich residues and modification of the thiosulfate method for ferrotitaniuni is given (65). Uranium. T h e interest in this element continues as is shown by the reviely (187) and books (40$ 186) recently published. The use of the lead (@), zinc spiral (138),and bismuth amalgam (150) reductors has been advocated. For ores, a mercury cathodecupferron modification has been proposed (176). Small amounts of uranium have been determined using chromous chloride as a reducing agent (60); sodium vanadate has been proposed as an oxidant (155). Vanadium. Modifications of the ferrous sulfate method have included a dead-stop end point, (80), a photometric end point (a?), and a method for steel (110). For the separate determination of vanadium( IV) and vanadium(V), bicarbonate and acetone are used to precipitate, followed by reduction of vanadium (1:) with ferrous sulfate and total vanadium by the persulfateferrous sulfate method (151). I n another method, vanadium (II), vanadium(III), and vanadyl(I1) are titrated with permanganate, and vanadium(II1) with permanganate using diphenylamine as indicator. T h c vanadium(I1) is oxidized to vanadium(II1) with silver(1) and then titrated (153). Water. There has been considerable interest in the Karl Fischer method as shown by reviews (114, 149, 150). Applications have been made to water in air (188)and gaseous hydrogen chloride (147). Suggestions for standardization of reagents (182) and the use of sodium tartrate dihydrate as a standard (166),as uell as improvements in measuring apparat,us, have heen madF (243). Zinc. Zinc is precipitated as oxalate using ethyl oxalate and thc precipitate is dissolved and titrated with permanganate (41 ). A modification of the oxine-bromate method has been used for aluminum alloys (211). Conditions for using the ferrocyanide method have been given (63). ACKNOW LEDGMEZIT
T h e authors wish to express their thanks to E m m a D. Andrews for assistance with the bibliography.
Anderson, K., and Revinson, D., Ax.4~.CHEM.,22, 1272 (1950). d ' h s , J., and Mattner, J., Angeur. Chem., A63,45 (1951). Bach, J. M.. Rev. obras. sa?&. nacion, 14, 140 (1950). Ballczo, H., Wien. Chem. Ztg., 50, 146 (1949). (9) Ballcao, H., and Sinabell, J., Mikrochemie aer. Mikrochim. Acta, 34,404 (1949). (10) Balyuk, S. T., and Rlirak'yan, V. M., Zaaodskaya Lab., 15, 1368 (1949). (11) Ihid.. 16, 100 (1950). (12) Beeghly. H. F., AN.\L. CHmi., 21, 1513 (1949). (13) Beerstecher. E., Jr., Analus4 75, 180 (1950). (14) Berkovich, M.T., Zacodskaya Lab., 16, 538 (1950). (15) Bertiaux, L., Chim. onal., 32, 269 (1950). (16) Bhunvara. K. B., and Khorana, VI. L., Analyst, 74, 601 (1949). (17) Bischoff, F., Mikrochemie zer. Mikrochim. Acta, 36/37, 251 ( 1951) . (18) Bischoff, F., Z . anal. Chem., 130, 195 (1950). (19) Black, R. M . , A n a l y s t , 75, 168 (1950). (20) Ibid., p. 208. (21) Blaedel, W ,J., and LIalmstadt, H. V., ANAL. CHEM.,22, 734 (1950). 122) Ihid.. D. 1410. Ihid.. b. 1413 Ibid.,23, 471 (1951). Blaedel, K. J., and Panos, ,J. J.. Ibid., 22, 910 (1950). Blake, G. G., Analtist, 75, 32 (1950). Ibid., p. 689. Ibid., 76, 241 (1951). Blom, Jakob, and Schwarz. Birgit. Acta Cham. Scand., 3, 1439 ( I 949). Blumenthal, H., Ax.41,.CHEM..23, 992 (1951). Boelter, E. D., Putnam. G. L.. and Lash, E. I., Ibid.. 22, 1533 (1950). Z. physiol. C'hern., 285, 93 (1950). Boguth, W.. AI.. CHEM..23, 980 (1951). Breit, Juanita E.. J . Assoc. Ofic. A g r . Chemists, 31, 573 (1948). British Standards Inst.. "Methods for the Analysis of Aluminum and Aluminum hlloys: Copper." Brit. Staizdards, p , 1728, Pt. I (19513. Burriel, F.. and Lucena-Conde, F., Anal. Chini. d c t r r , 4, 344 (1950). Burriel, F., and Lucena-Conde, F., A n a l e s fis. y qtcim. ( M a d r i d ) , 45B, 15 (1949). Ihid., 46B, 577 (1950). Burriel, F., Pino Perez, F., and Ortia, J., I t i d , , 45B, 577 j1949). Burstall, F. H., and Williams, .1.F., "Handbook of Chemical Methods for the Determination of Uranium in Minerals and Ores," London, H. M.Stationery Office, 1950. Caley, E. R., Gordon. I,..and Simmons, G . A , , J r . , AXAL. CHEM.,22, 1060 (1950). Casares Looez. D.. A n a l e s rcnl. acnd. .f o r m . . 16. 117 fl950). Celsi, S. A , . and Copello, 11. .I., Man. f a r m . u t e m p . ( M a d r i d ) , 57, 158 (1951). Cheburkova, E. E.. Ziri~odsku!/oLnh.. 16, 663 (1950). Ihid.. p. 1009. Clarke, F. E.. .1s.tt.. ('HEM., 22, 553 (1950) Ihid.. p. 1458. C'lulev. H. J.. Ancilusl. 76. 517 il9511. , Cook;. W. D.. Hazil, F..'and McNahb, \I-. h i . , .ls.t~. CHEW, 22, 654 (1950). Cooke, Wilriam D.. Hazel, Fred, and McSabb. Xallace hl., Anal. Chim. A c t o , 3, 656 (1949). Datsenko, 0. V.,Zoiod.skrcl/o Lab.. 16, 784 (1950). DBvila, J. G.. Eng. M i i i i i i g J . , 151, 81 (1950). Delgado Martinez, Felipe. Iiist. hierro 2~ ncero. 2, S o . 6, 67 (1949). Dey, Arun K.. C'io.wr2l Scr'. (I?!diii),18, 132 11949). Duggan. R. E.. J . A s s o c . O f i c . A g r . Chemists, 31, 568 (1948). Duval, Rene. Ann. mines ('2 carbicmnts. 138, KO.2, 3 (1949). Eaton, F. C., hiatviak, 11..and Koskey. P. J., ( ' h r ~ n i s t - l r ~ a l y s t , 39,28 (1950). Eggertsen. F. T., and Ilohei~ts.R. h l , , .Ax.\I.. C H n f . , 22, 924 (1950). Eichler. -I,, Z.a n a l . ~ ' / I ~ ~ V I129, .. 396 (1949). Fainberg. 6. T u . . Zaichikora, L. B., and Fraiberg. S. M., Znrodakawn Lab.. 16.771 (1950). , , , FehBr, F.. Klug, H.. a i d Emmerich, L.. Z. nnory. C h e m . , 260, 273 (1949). Fernandez, J. B., Snider. L. T., and Rieta, E. G.. A N ~ LCHEM., . 23,899 (19511. Finkel'shtein, D. S . ,and Benevolenskaya, Yu. d.,Zrrcodskayn Lob., 16,907 (1950). Fiore. Luisa, A n n . chinz. npplicata. 39, 523 (1949). Flaschka, H . , -4ncrl. Chinz. Acta. 4, 242 (1950). Flaschka. H.. Mikrochernie zer. Mikrochim. Acta. 35, 36 (1950). Ihid.. p. 473. (5) (6) (7) (8)
.
(1) Aleksandrov, G. P..and Sherchenko, E. A , , Zarodskaya Lab., 15, 1474 (1949). 12) American Society for Testing Materials, "1950 Book of AST3I Methods for Chemical Analysis of Metals," Philadelphia, 1950. ( 3 ) Amiel, Jean, and Nortz, hlaurice, Bull. soc. chim. France, 1950, 226. (4) Analytical Chemists' Committee of Imperial Chemical Industries, Ltd., A n a l y s t . 75, 577 (1950).
,
~~
~
LITERATURE CITED
I
~
I
,
I
V O L ' U M E 24, N O .
1, J A N U A R Y 1 9 5 2
( 6 8 ) Ibid., 36/37, 269 (1951).
(69) Ibid., 38, 15 (1951). (70) Flaschka, H., Monatsh., 80, 506 (1949). (71) Flaschka, H., Wien. Chem. Ztg., 50, 89 (1949) ( 7 2 ) Flaschka, H., and Spitzy, H.. Mikrochemie ~ e r .Mikrochim. a c t a , 35, 306 (1950). (73) Flaschka, H., and Zavagyl. H., 2. ur~nl.Chem., 132, 170 (1951). (74) Fossum, J. H., Markunas, P. C . . and Riddick, J. A , , h s a ~ . CHEM., 23, 491 (1951). (753 Fukuei. Y . .J . Soc. Org. Synthctic C'hem. ( J a p a n ) , 7, 27 (1949). (76) I.'uiiasaka, IT-,, J . J a p u n . Chem.. 4, 125 (1950). ( 7 7 ) I'unck, E., TT-ackernagel,K., and Frober, Karl, Phcirm. Z t g . , 85, 561 (1949). (78) Furness, W,, Analyst, 75, 2 (1950). (79) Fyfe, IT. S., ANAL.CHEM.,23, 174 (1951). ( 8 0 ) Gale, R. H., and Nosher. E.. Ibid.. 22, 942 (1950). (81) Garwin, L., and Hixson. -4.S . .Ibid., 21, 1215 (1949). CNbhart, F., Ann. p h o i m . .fran$.. 7, 40 (1949). I h i d . , p. 136. Leiicke, S., and Kurniies, B., L a n d w . Forsch.. 3, 46 (1951). Geiicke, S., and Kurmles, B., 2. anal. Chem., 132, 335 (1951). Glcmser, O., and Thelen, L., Angew. Chem., 62, 269 (1950). Goddu, R. F., and Hume, D. K., ~ ~ N A CHEM., L . 22, 1314 (1950). Goehring, Margot, and Schlaich, Johanna, 2. anal. Cirem., 129, :319 (1949). Goeta, C. A., Diehl, H., and Hach, C. C., .ixar.. C'HEM.. 21, , 1520 (1949). (;o~izhlesCarrerd, J.. A n u l e s fis. y q u i n ~ . ( M a d r i d ) , 45B, 7 3 (1949). Hahn, F. L., Aual. Chi7n. Acta, 4, 573 (1950). Hall, J. L., and Gibson, J. A., J r . , ASAL.CHEM.,23, 986 (1951). Hardin, L. J., and NacIntire, IT, H., J . Assoc. Offic. -4gr. Chemists, 32, 439 (1949). Hardwick. P. J., Analyst, 75, 9 (1950). Harris, F. K., Ibid., 75, 496 (1950). Harrison, T. S., and Storr, H., A n a l y s t , 74, 502 (1949). Haslam, J., Ibid., 75, 371 (1950). Haslam, J., and Moses. G., Ibid., 75, 343 (19.50). Hazel, W.BI., and Ogilvie, G. H., ASAL.CHEM.,22, 697 (1950). Hernandez-Gutibrrez, F.,I n f o r m . puim. anal. (Madrid),4, 205 (1950). Higuchi, Takeru, and Concha, Jesusa, Science, 113, 210 (1951). Hol, P. J., Chem. Weekhlad, 46, 614 (1950). Ihid., p. 651. Holness. H., Analyst, 74, 457 (1949). Houghton, G. E., Ibid., 75, 180 (1950). Hyazu, Ryoichi, J . Phnrm. S O C .J a p a n , 71, 135 (1951). Ikegami, Hiroshi, J . Cheni. S O C .Japan, 52, 173 (1949). Iritani, N.,J . P h a r m . Soc. J a p a n . 68, 63 (1948). Ishibashi, I. N., and Kusaka, T., J . Chem. SOC.J u p a n , 71, 180 (1950). Jahoulay, E). E., Rev. niBt., 46, 710 (1949). ,Jacohsen, C.F., and LBonis, JosB, Compt. rend. trar. lab. Curlsberg, Ser. chim., 27,333 (1951). James, IT. d.,and Belser, R. E., As.\L. CHEM.,23, 1037 (1951). Jensen, F. IT., Watson, G. lI.,and Vela, L. C . , Ibid., 23, 1327 (1951). Jones, A. G., A n a l y s t , 76, 5 (1951j . Kakita, Tachiyo, Science Repts. Research Inst. TGhoku I m p . Vniv,, Sei-. 8 ,2, 255 (1950). Kallmann, S., As.I.,French Patent 940,104 (Dee. 3, 1948). Rodden, C. J.,ed., ".inalytical Chemistry of the BIaiihattan Project," S e w Tork. i\lcCraw-Hill Book Co., 1950. Rodden, C. J., and Tregoning, J. ,I,, "hlanual of Analytical Methods for the Determination of Uranium and Thorium in Their Ores," Washington. D. C., U. 8. Govt. Printing Office, September 1950. Roman, IT., and Hirst, d., A4nalyst,76, IO (1951). Rulfs, Charles L., Anal. C h i m Acta, 5, 46 (1951). Rynasiewics, J., and Polley, h l . E., ASAL. CHEM..21, 1398 (1949). Sack, IT.,2. anal. Che?~z.,131, 199 (1950). Sawaya, T.. J . Chem. Soc. J a p a n , 71,292 (1950). Schleicher, A., 2. a n a l . Chem., 131,245 (1950). Schleicher, J., and Pivet, L., Rol. soc. chilenu q f i i m . , 1, 9 (1949)
ANALYTICAL CHEMIS’TRY
108 (195) Schreyer, J. M., and Ockerman, L. T., ANAL.CHEY.,23, 1312 (1951). (196) Schreyer, J. M., Thompson. G. W., and Ockerman, L. T., Ibid., 22, 691 (1950). (197) Ibid., p. 1426. (198) Schtitr, H., Fette u. Seifen, 51, 433 (1944). (199) Seaman, W., and Allen, E., ANAL.CHEM.,23,592 (1951). (200) Shlyapin, B. P., and Pevneva, 2. P., Zavodskaya Lab., 16, 661 (1950). (201) Sill, C. W.. and Peterson, H. E., ANAL.CHEM.,21, 1268 (1949). (202) Smith, F. W.,and Gardner, D. E., Arch. Biochem., 29, 311 (1950). (203) Smith, G. F., “Analytical Application of Periodic Acid and Iodic Acid and Their Salts,” Columbus, Ohio, ‘2. Frederick Smith Chemical Co., 1950. (204) Soibei’man, B. I., Zhur. Anal. Khim., 3, 258 (1948). (205) Sosnovskii, B. A , , Zavodskaya Lab., 16,872 (1950). ANAL.CHEM.,23, 1331 (1951). (206) Stanton, L. (207) Steinita, K., Mikrochemk urn. Mikrochem. Acta, 35, 176 (1950). (208) Stock, J. T., Metallurgia, 42, 48 (1950). (209) Stock, J. T., and Fill, M. A., Ibid., 41, 170 (1950). (210) Ibid., p. 239. (211) Stokowy, E., 2. Metullkunde, 41, 347 (1950). (212) Stone, H. W., and Eichelberger, R. L., ANAL.CHEM.,23, 868 (1951). (213) Swift, E. H., Arcand, G. M., Gutwack, R., and hfeier, D. J., Ibid., 22,306 (1950). (214) Syrokomskir, V. S., and Gubel’bank. S.M., Zhur. Anal. Khim., 4 , 146 (1949). (215) Ibid.,p. 203. (216) SyrokomskiI, V. S., and Knyareva, R. N., Zaeodskaya Lab., 16, 1041 (1950). (217) Syrokomskii, V. S., and Melamed, S. I., Ibid., 16,273 (1950). (218) Syrokomski:, V. S., and Silaeva, E. V., Ibid., 15, 1015 (1949). (219) Ibid., p. 1149. (220) Saabo, Zoltan G., and CsBnyi, Lhrl6, Magyar Chem. Folydirat, 56,112 (1950).
s.,
(221) Sznho, Z.. and Sugbr, E., . ~ - . A L . CHEM.,22,361 (1950). (222) Sreberhyi, Pbl, Magyar Kdm. Lapja, 4, 353 (1949). (223) Takagi, K., and Yamada, AT., J. Electrochem. Assoc. Japan. 18, 9 (1950). (224) Talpade, C. R., PTOC. Natl. Acad. Sci., India, 11A, 1 (1941). .. 21, (225) Taylor, J. K., and Escudero-Molins, E., ~ ~ N . A I CHEM., 1576 (1949). (226) Thornson. S. M., Ibid., 23, 973 (1951). (227) Tinsley. ,J., Taylor. T.G.. and Moore, J. H., Analyst, 76, 300 (1951). (228) Titova, Tu. G., Zhur. Anal. Khim., 6, 51 (1951). (229) Tomibek, O., Sandl, Z., and Simon, V., Collection (‘rrchoslov. (‘hwn. Communs.. 14, 20 (1949). (230) Trtilek, J., Chem. Listy, 38, 128 (1944). (231) Trump. W. S . , and Smith, L., Proc. Iowa A c a d . Sci.,55, 277 (1948). (232) Tsubaki, I., J. Chem. Soc. Japan, 71,454 (1950). (233) Urusovskaya, L. G., and Zhilina, P. I., Zaaodskaya Lub., 15, 740 (1949). (234) Usatenko. Yu. I., and Datsenko, 0. O., Ibid., 16, 94 (1950). (235) V&jna, S.,and Gabos-Pint&-, M., M a g y a r Chem. Foly6i~at,56, 63 (1950). (236) Vetrov, A. S., Zavodskaya Lab., 16, 362 (1950). (237) Vogel, H. C. v . , Arch. Eisenhiittenw., 20, 287 (1949). (238) Vorob’ey, A. S., Zhw. Anal. Khim., 4, 200 (1949). (239) Watson, J. P., Analyst, 76, 177 (1951). (240) Welte, H., Siiddeut. Apoth.-Ztg., 89, 698 (1949). (241) Weste, F., Arch. Metallkunde, 3, 147 (1949). (242) Whitnack, G. C., Holford, C. J., Gantr, E. St. C., and Smith, 0. B. L., ANAL.CHEM., 23, 464 (1951). (243) Wberlev. J. S.. Ibid.. 23. 656 11951). (244; Wi1lard:H. H., and Horton, C.~A.,Ibid., 22, 1194 (1950). (245) Wllson, A. E., Ibid., 22, 1571 (1950). (246) Wilson, H. N., Analyst, 76, 65 (1951). (247) Wogrinz, A., and Kudernatsch, G., Prakt. Chem., 1950, 197. (248) Zavgorodnii, S. F., Zavodskaya Lab., 15, 363 (1949). RECEIVED Sovember 12, 1951.
Volumetric Analytical Methods for Organic Compounds WALTER T. SMITH, JR., AND ROBERT E. BUCKLES State University of Iowa, Zowa City, Iowa
T
H I S discussion is based primarily on reports t h a t have b e come available from September 1950 t o October 1951.
DETERMINATION OF ELEMENTS HALQGENS
I n a new variation on the Parr bomb fusion a nickel bomb (with 0.3% manganese) of 10 ml. capacity is used. Eight drops of ethylene glycol and the sample are placed in the bomb a n d covered with 3 to 11 grams of sodium peroxide. T h e bomb is closed and heated with a microburner for 10 t o 20 seconds t o ignite the mixture. After about 50 seconds of heating the bomb is quenched in water. One of t h e advantages claimed for this decomposition procedure lies in the fact t h a t the bomb is not subjected to as severe service ae in the usual sugar-sodium peroxide procedure because the ignition temperature of the sodium peroxide-ethylene glycol mixture is 58” (161). However, i t seems t h a t this low ignition temperature constitutes a safety hazard, and care should be exercised in using this method. T h e following methods are used b y Martin ( 9 4 ) for analyzing t h e decomposition products from t h e usual sodium peroxide Parr bomb fusion. T h e residue from the fusion is dissolved, boiled t o decompose sodium peroxide, and treated with sufficient nitric acid t o bring t h e concentration of the final solution to 25% nitric acid. Chloride is determined b y the usual methods after bromine and iodine are removed b y passing air or nitrogen through t h e solution. Bromide is oxidized b y sodium hypochlorite to bromate arid the excess hypochlorite is removed b y the addition of sodium for-
mate T h e bromate is then determined iodometrically. This method cannot be used in t h e presence of iodide. Iodide is oxidiized b y bromine water in neutral solution, and after t h e bromine is boiled off, the iodate is determined iodometrically. I n a combustion method a tube filled with quartz wool is used. T h e products of t h e decomposition are absorbed in a mixture of 3 ml. of Perhydrol and 7 ml. of water contained in a detachable s iral. T h e halide is determined argentometrically using dicborofluorescein indicator (46). T h e method of Freeman and ,1IcCullen (40)has been modified and subjected to collaborative study. T h e soniea h a t variable results indicate that further study is necessary before the procedure can be recommended ( 1 4 2 ) . Two methods for the determination of halogens in halogenated fluoresceins (8, 6 7 ) have been studied collaboratively M ith satisfactory results (66). Organic bromine compourids may be decomposed by treatment with lead-free zinc and 10% sodium hydroxide solution, followed b y oxidation of the organic residue with permanganate ( 4 7 ) An alternative is to decompose a 3- to 4-gram sample by adding i t t o melted potassium. T h e ewess potassium is decomposed T\ith methanol and the methanol is removed b y distillation (71). T h e analysis of fluorocarbons has been discussed in some detail. A combustion train is described which permits the determination of carbon, fluorine, and chlorine in a single sample if the sample contain. no hvdrogen (85). T h e determination of fluoride has been revieir ed n ith particular attention paid to the titration of fluosilicic acid tvith thorium nitrate using sodium alizarin sulfonate as indicator.
