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A study of methods for the determination of thallium in toxicological analysis

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A study of methods for the determination of thallium in toxicological analysis

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Content A STUDY OF METHODS FOR THE DETERMINATION OF THALLIUM IN TOXICOLOGICAL ANALYSIS a 3L A Thesis Presented to the Faculty of the Department of Chemistry University of Southern California In Partial Fulfillment of the Requirements for the Degree Master of Science in Chemistry fey Paul G# Summers May 1936 UMI Number: EP41482 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. UMI EP41482 Published by ProQuest LLC (2014). Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106- 1346 This thesis, w ritten under the direction of the candidate's Faculty Committee and approved by all its members, has been presented to and ac cepted by the Council on Graduate Study and Research in partial fulfillm e nt of the require ments for the degree of MSTER..QE1 .aeiENCE 'ecretary Dean Date Jy3.et.1936 Faculty Committee hairmai TABLE OF CONTENTS PAGE THE PROBLEM AND ITS IMPORTANCE.............. 1 HISTORY OF THALLIUM AND A REVIEW OF THE LITERATURE . 3 DESCRIPTION OF MATERIALS AND APPARATUS....... 23 METHODS USED AND EXPERIMENTAL RESULTS ........ 24 SUMMARY AND CONCLUSIONS.................... 33 BIBLIOGRAPHY......... 34 LIST OF TABLES TABLE PAGE I. Precipitation as Thallic Hydroxide ....... 15 II. Determination of Thallium as the Acid and Neutral Sulphates • • ........ ...... 14 III. Determination of Thallium as Thallous Chrornate . 16 IV. Volumetric Estimation of Thallium ....... 17 V. The Determination of Thallium as Thallous Chromate.......................... 26 VI. The Determination of Thallium as Thallous Iodide................................ 28 VII. The Determination of Thallium as Thallic Oxide .......... ............... 29 VIII. The Colorimetric Determination of Thallium in Toxicological Material by the Liberated Iodine .......................... 32 THE PROBLEM AND ITS IMPORTANCE The continued commercial use of thallium as a depila tory agent in cosmetical creams and as a toxin in rodenti- cidal compounds has resulted in numerous instances requiring the determination of small quantities of thallium in toxico- logical materials. Various procedures for such a determination have been recommended, but an analysis of the methods now in general use shows many of them either to be cumbersome, lengthy, or lacking in certain elements of technique that are essential to accuracy in a quantitative determination. Too often the procedure recommended sponsors a process that makes a com plete separation of the element sought from the many complex substances present in. toxicologica.l materials virtually im possible, even though acceptable results have been reported by the proponents of these methods for simple test solutions. The Problem. It was the purpose of this investiga tion to make a study of methods for the determination of small quantities of thallium in toxicological material and to compare experimental results with the results previously reported by other investigators. Importance of the Study. The toxic nature of thallium compounds has long been recognized, but effective legal meas ures to prevent its continued use in commercial products have not yet been enacted. As a result of negligence in this matter, cases of blindness, followed by death are occasional ly recorded throughout the world, as a result of thallium poisoning. Not long ago a widely publicized account of such a case involving eleven victims of thallium poisoning appeared in this state. Under such circumstances, it may readily be seen that instances will arise that require the identification and ac curate determination of minute quantities of thallium in toxi- cological materials, and it is most important that the chemist be adequately prepared to meet such a situation when the ac tual need arises. HISTORY OF THALLIUM AND A REVIEW OF THE LITERATURE History of Thallium. Thallium was discovered spectro scopically in 1861 by Sir William Crookes. Most of the early work on the element was done by Crookes. He studied its chem ical properties, isolated and purified the metal, investigated its sources, and proposed methods for its determination that have yet to be improved upon. Occurrence of Thallium. Upon examining a large col lection of ore samples from different parts of the world, Crookes**- found, thallium to be a widely distributed consti tuent of iron and copper pyrites. Among the ores analyzed, it was found to be present in more that one-eigth, though the amount present seldom exceeded from 1/100,000 to 1/4,000 of the total bulk of the ore. Other sources of the metal include: (l) Sweedish crooksite, (CuTlAg)gSe, containing 16 per cent to 19 per cent Tl; (2) lorandite, TlAsSg, from Mace donia, containing 59.5 per cent Tl; (3) hutchinsonite, a com plex sulfide, containing 18 per cent to 25 per cent Tl; (4) vrbaite, TlAs„Sb , containing 29 per cent to 32 per cent Tl; ^ o 9 zinc blende; and hematite.'' It may also be present in the **W. Crookes, Select Methods in Chemical Analysis. (New York: Longmans, Green and Company, 1905), p. 164. ^A.B. Prescott and O.C. Johnson, Qualitative Chemical Analysis. (New York: Van Nostrand Company, 1933), p. 191. mud and flue dust from sulphuric acid plants, and even in commercial sulphuric and hydrochloric acids. Properties of Thallium. Freshly cut metallic thallium has a silvery-white luster with a distinct blue-grey tinge. It is readily oxidized in moist air, but may be preserved under water that is free from dissolved oxygen. It is soft er than lead. It is malleable and may be extruded but not drawn into a wire. It is a poor conductor of electricity, and stands between iron and cobalt in the electromotive series. Its crystalline structure exists in two modifica tions, and the transition temperature is 226°. The various compounds of thallium are poisonous. Symptoms of thallium poisoning are: (l) restlessness, (2) salivation, (3) cata racts, followed by total blindness, (4) loss of hair, (5) bleeding of the lungs, and (6) finally death in from three 4 to five days due to respiratory distresses. In general, thallium compounds are relatively insolu ble in inorganic solvents other than HNOg, H^SO^, and aqua regia. Thallium salts, however, are quite readily soluble Crookes, op. cit., p. 165. ^H.M. Ginsburg and C.E. Nixon, f , Thallium poisoning.1 1 Journal of American Medical Association, 98: 1076-77, 1932. ^W.W. Scott, Standard Methods of Chemical Analysis. 4th edition. (New York: Van Nostrand Company, 1925), p . 140. 5 in organic solvents such as acetic ether, and a mixture of 6 absolute ethyl and methyl alcohols, according to Bottger. Compounds of Thallium. Thallium forms two well de fined series of compounds: those in which the valence is one are the thallous compounds, and those in which the valence is three are thallic compounds. The behavior of the element in any given analysis will depend to a large extent upon its valence. Thallic salts may be prepared by oxidizing thallous salts with chlorine, potassium permanganate, sodium peroxide, and other similar oxidizing agents. On the other hand, thal lic salts may be reduced to the thallous condition by treat ment with stannous chloride, sulpherous acid, hydrogen sul fide, ferrous sulfate, and arsenous compounds. A still fur ther reduction to metallic thallium may be brought about by treating thallous salts with metallic zinc, magnesium, and aluminum. Uses of Thallium. Commercially, thallium is relative ly unimportant. Small quantities of the metal are used, how- 7 ever, in insecticidal and rodenticidal compounds as its various salts are odorless and tasteless. Because of its 6 Bottger, cited in Comeyfs Dictionary of Chemical Sol ubilities . (New York: The Macmillan Company, 1896), pp. 469-70. ^ Munch and Silver, The Pharmacology of Thallium and its Use in Rodent Control. U.S. Department of Agriculture, Technical Bulletin, 238, April, 1931. depilatory action, it has been, and still is being, used quite g disastrously in commercial hair removers* An English con cern has found a further use for the element and is using it 9 as an anti-knock compound in gasoline* Because of its high index of refraction, it is used in the manufacture of optical glass and artificial stones.^ It is also used as a component in certain alloys* An alloy consisting of 10 per cent thal lium, 20 per cent tin and 70 per cent lead that resists the action of sulphuric, nitric and hydrochloric acids has been reported. Detection of Thallium. In the regular course of qual itative analysis, thallium passes into the zinc-nickel group. It may be separated from lead by boiling the solution in ques tion with sulphuric acid. The lead sulphate thus produced may be removed from the solution by filtering. Thallium con tained in the filtrate from the lead separation may be re moved from iron, aluminum, the zinc-nickel group, and the alkaline earths by oxidizing the filtrate with nitric acid, ^R. Fridli, wEine Thalliumvergiftung.1 1 Deutsche Ztschr. f* d. ges. Gerichtl. Med.. 21: 461-462, 1933. ^British Patent, No. 249,560. 10 T.W. Case, wThalofide cell - a new photo-electric sub— stance.1 1 Physical Reviews. (2), 15: 289-292, 1920. ^British Patent, No. 297,665. 12 boiling with sodium carbonate, and filtering. Thallium contained in this filtrate may be precipitated as thallous sulphide, TlgS, with ammonium sulphide after the solution has been made ammoniacal. The resultant brown precipitate of thallous sulphide may be dissolved in dilute nitric acid and subjected to the following tests, each of which gives a characteristic reaction that will prove valuable in the iden tification of thallium. 1. Spectroscopic Determination of Thallium. If the loop of a platinum wire be moistened with thallous nitrate solution, and held in the outer portion of the Bunsen flame, a characteristic green color will be imparted to the flame, which when viewed through the spectroscope will appear as a 13 green line at 5350.6 angstrom units. If the glare of the sodium line is cut out, as low as 0.0002 per cent of thallium 14 can be detected in 0.03 grams of material. Other tests for the determination of thallium are incorporated in chart form on the following page. 19 W.W. Scott, 0£. cit., p. 140. 13 Stonley, Lines in the Area Spectra of Elements. (London: The Adam Hilger Company, 1911), p. 27. 14 W.F. Hillebrand and G.E.F. Lundell, Applied Inorgan ic Analysis. (London: Chapman and Hill, Ltd., 1929), p. 374. Treatment Comp, of ppt. I II III IV V VI VII VIII IX Concentrate a few drops of TINOg so^n, by evaporation, then add dilute HC1. Neutralize TINOg solfn. with NfLOH, then acidify with CH3C00H and add KI sol»n. Neutralize TINOg solfn. with NH^OH and add a slight ex cess. Ppt. with KCrQ4 sol!n. Treat a few drops of the TINOg sol*n with chloroplati- nic acid •Dissolve (NH^)gCOg crystals in uranyl acetate neutralized with NH4OH and add TINOg sol'n. Add KNOg and CH5C00H to a sol ution of TINOg and warm gently To a sol*n of TINO3 add a mix ture of SbClg and KI; then warm gently To a sol*n of TINO^ add some alkali molybdate solfn., and warm Add to a sol*n. of TINOg some alkaline tungstate sol*n. T1C1 Til TlgCr04 TlgPtClg T12C03- uo2 So5 T15C0(N02)6 3TlI#2SbIg TlgMoO^ TlgW04 Color Sensitivity in Authority micro mgs. White 0.16 Lindsley 15 Yellow 0.17 16 Yellow Moser and Reif ^ Yellow 0.008 Lindsley 18 Yellow 0.1 19 Red Orange Red Prescott Scott^ 20 Yellow 0.033 Lindsley 22 Iridescent plates 0.08 23 ■^L.C. Lindsley, Industrial Microscopy. (Richmond: The William Byrd Press, Inc., 1929), p. 79. -^Ibid.. p. 151. *^L. Moser and W. Reif, Mikrochem. Emich. Festschr., 1930. pp. 215-218. •^L.C. Lindsley, op. cit., pp. 79-80. 19Ibid., p. 151 and 158-159. 20 A.B. Prescott and O.C. Johnson, op. cit., p. 192. 21W.W. Scott, op. cit.., pp. 14-141. 22 L.C. Lindsley, pp. cit., pp. 151 and 154. 23 Ibid., pp. 151, 155, 159. 1. T1C1 2. Tlgft- - Cl~ 3. T15Mo04 ° 4« Tl CrO 5I Tj|s04 + KNOg 4 (CHgC00)2U03 REVIEW OF THE LITERATURE In any given analysis, when the presence of thallium has been proven, it then becomes a problem to determine the amount present. Perhaps as many methods for the determina tion of this element have been proposed as there are char acteristic tests for its identification. Some of the most important of these methods will be reviewed on the following pages so that later investigators may have this data before them. It is to be remembered, however, that some of these methods are included only for completeness and have not necessarily been tested in the pre sent investigation. Crookes, the discoverer of thallium, has proposed a number of methods for its quantitative determination. His gravimetric methods, based on the precipitation of insoluble thallium salts that are removed from solution by filtration, dried, and weighed, have proven quite valuable for the deter mination of thallium in simple test solutions. Browning, working in collaboration with Palmer and Hutchins has carried out experiments on the analysis of thal lium, working with quantities ranging from 79 to 160 milli grams. Some of their experiments were conducted under condi tions similar to those proposed by Crookes. It will prove interesting to review their experimental results. Determination of Thallium by Precipitation of Thallic Hydroxide. For the gravimetric estimation of thallium pre cipitated as thallic hydroxide by potassium ferricyanide and potassium hydroxide, and its subsequent oxidation to thallic £4 oxide by heating. Browning and Palmer found the following* results listed in Table I. The Gravimetric Estimation of Thallium as the Acid Sulphate. TIHSQ^. and as the Neutral Sulphate. Tl^SO^. £5 Crookes , first found that thallium precipitated as the sul phate by the action of sulphuric acid, when evaporated to dryness and heated to redness had the composition of a neutrall sulphate that could be further heated without appreciable loss £6 of weight. Castanjen further observed that the acid sul phate tends to lose acid on strong ignition in the air. £7 Browning _ has shown, however, that under proper conditions thallium may be determined either as the neutral sulphate or as the acid sulphate. His experimental results are recorded in Table II. 24 Browning and Palmer, American Journal of Science. (£), £7: 380. Reprinted in F.A. Gooch, Methods of Chemical Analysis. (New York; John Wiley and Sons, 1912), p. ££0. 25 Crookes, Chemical News, 8: £43. P6 Castanjen, Jour. Prakt. Chem., 102: 131, £7 Browning, American Journal of Science. (4), 9:137. Reprinted in F.A. Gooch, ojq. cit.. p. ££0. . TABLE I PRECIPITATION AS THALLIC HYDROXIDE 5 Og taken as [lous nitrate Tl^Og found Error grin. grm. grm. 0.1305 0.1309 *0.0004 0.1305 0.1314 *0.0009 0.1505 0.1308 +0.0003 0.0870 0.0872 +0.0002 0.1740 0.1741 -0.0001 0.1740 0.1739 +0.0001 0.1740 0.1742 +0.0002 0.1305 0.1307 +0.0002 0.1305 0.1309 +0.0004 0.1305 0.1308 +0.0003 0.0870 0.0872 +0.0002 0.0870 0.0874 +0.0004 TABLE II DETERMINATION OF THALLIUM AS THE ACID AND NEUTRAL SULPHATES TIHSO^ calculated tihso4 found Error Tl^SO, calcula grm. grm. grm. 0.1605 0.1611 0.1608 0.1612 0.1602 0.1608 0.1617 .0.1608 0.1609 0.1596 0.1608 0.1608 0.1600 0.1596 0.1596 0.1604 0.1592 0.1590 i i i i i i it ooooooooo • ••••«••• ooooooooo HHHHOHOOO COOWfOO^OWCD 0.1344 0.1349 0.1347 0.1350 0.1341 + «•••• 0.1347 0.1348 TlgSO^ found grm. 0.1546 0.1346 0.1353 0.1346 0.1346 0.1358 0.1346 Error 4*0.0002 -0.0003 +0.0005 -0.0004 +0.0005 +0.0011 - 0.0002 15 The Gravimetric Estimation of Thallium as the Chrornate. Browning and Hutchins28 have described conditions under which the determination of thallium as the chrornate gives exact quantitative results. Their procedure, in gen eral, is based on the precipitation of thallous chromate by the addition of potassium dichromate to a hot ammoniacal sol ution of thallous nitrate. This method for the analysis of thallium was first proposed by Crookes, and the experimental results of Browning and Hutchins that appear in Table III tend to confirm the reliability of the method. The Estimation of Thallium by the Action of Potassium Ferricvanide in Alkaline Solution and of Potassium Permanga nate in Acid Solution upon the Ferrocvanide Produced. For 29 the volumetric estimation of thallium, Browning and Palmer have proposed a process based on the oxidation of a thallous salt with precipitation of thallic hydroxide by the action of potassium ferrieyanide and potassium hydroxide and the subsequent oxidation of the potassium ferrocyanide produced, after filtration of the mixture. 28 Browning and Hutchins, American Journal-of Science. (4), 8: 460. Reprinted in F.A. Gooch, ojs. cit.. p. 222. 29 Browning and Palmer, American Journal of Science. (4), 27:379. Reprinted in F.A. Gooch, op. cit.. pp. 223-224. TABLE III TlgNOg taken TlgCrO^ found Error calculated as TlgO calculated as Tl^O calculated as 0.0796 0.0791 -0.0005 0.0792 0.0788 -0.0004 0.0792 0.0786 -0.0006 0.1188 0.1177 -0.0011 0.1192 0.1186 -0.0006 0.1185 0.1178 -0.0007 0.1190 0.1185 -0.0005 0.1189 0.1183 -0.0006 0.1196 0.1200 +0.0004 0.1196 0.1205 +0.0009 0.1173 0.1173 0.0000 0.1171 0.1163 -0.0008 TABLE IV VOLUMETRIC ESTIMATION OF THALLIUM taken as the ^^2^3 ^oun(i Error nitrate grm. grm, 0.0809 0.0809 0.0809 0.1213 0.1213 0.1213 0.1213 0.1213 0.1213 0.1618 0.1618 0.1618 0.0809 0.0808 0.0809' 0.1212 0.1216 0.1218 0.1218 0.1212 0.1207 0.1614 0.1613 0.1616 0.0000 - 0.0001 0.0000 - 0.0001 +0.0003 +0.0005 +0.0005 - 0.0001 -0.0006 -0.0004 -0.0005 - 0.0002 18 The essential steps in the procedure are represented by the following equations: (1) TlgO + 4K3Fe(CN)6 + 4K0H= Tl^Og + 4K4Fe(CN)6 + (2) 5K4Fe(CN)6 + KMn04 + 4HgS04= 5K3Fe(CN)6 +3KgS04 + MnS04 + 4HgO In this determination, it is necessary to apply a cor rection for the amount of permanganate required to give the first tinge of pink color to the amounts of ferricyanide used in this estimation, but this seldom exceeds 0.1 ml. of the standard permanganate. A Review of Methods for the Determination of Thallium .in..Toxicologica 1 Materials. In the discussion that has pre ceded, only methods for the determination of thallium in simple test solutions have been considered. Of the various methods proposed for the determination of thallium in toxicological 30 31 materials, those described by Shaw , Munch and Silver , 33 Lepper , and Fridli , are perhaps the best known. For this reason, these methods will be considered in the following paragraphs. 30 P.A. Shaw, Colorimetric Determination of Thallium.” Industrial and Engineering Chemistry. Anal. Ed.. 5: 93-95, 1933. 31 J.A. Munch and J. Silver, oj>. cit. 3%. Lepper, Z. Anal. Chem.. 79: 321-324, 1930. 33R. Fridli, Deut. Z. ees. Gerichtl. Med.. 15: 478-488, 1930. Chemical Abstracts . 1931. 19 Shaw has proposed a colorimetric method for the deter mination of thallium in organic matter based on comparing the color intensity of iodine liberated when thallic chloride is reduced to thallous chloride by the action of potassium iod ide, Briefly, Shaw!s procedure is as follows: The weighed and finely divided sample of toxicological material is reduc ed to a fluid mass with 6 normal hydrochloric acid, brought to boiling on the water bath, and oxidized in the usual man ner by successive additions of potassium chlorate. The cool ed solution is then filtered and washed to remove undecompos ed fatty particles, and then evaporated till a slight darken ing is noted. The cooled solution is then transferred to a separatory funnel and chlorine water is added in excess. The thallium contained in solution is extracted with 250 ml. portions of ether by shaking vigorously for two minutes, allow ing the liquid layers to separate and draining the ether por tion into a narrow-necked flask. The ether extract is eva porated nearly to dryness, and to the residue is added 15 ml. of water, a few drops of hydrochloric acid, 2 ml. of concen trated sulphuric acid and the solution is then placed on the hot plate until the fumes of sulphur trioxide are expelled. Concentrated nitric acid is then added, drop by drop, until oxidation is complete and a colorless or pale yellow solution remains. The solution is then cooled and 30 ml. of ammonium chloride solution, 150 g./liter, is added. The solution is 20 then evaporated to dryness, after which the thallous chloride contained in the residue is oxidized to thallic chloride with bromine water. After the excess of bromine has been removed by boiling, potassium iodide is added, and iodine is liberat ed as in the following equation: TIClg + SKI T1C1 + 2KCI + Ig The liberated iodine is then extracted with 20 ml, of carbon disulphide, and the color intensity is matched with a previously prepared set of standards with the aid of a colori meter. 34 Munch and Silver have reviewed a volumetric method, proposed' by a German concern, for the determination of thal lium in grain. It is reported that this method gives good results and requires no particular skill to operate. In brief, the procedure is as follows: A given mass, usually one gram, of the material thought to contain thallium is intimately mixed with about 20 grams of anhydrous sodium carbonate, and heated in a por celain crucible for about one hour just under fusion tempera ture. The ash is then transferred to an Erlenmeyer flask and the crucible is thoroughly washed with hydrochloric acid. The washings are added to the flask, and when all of the sodium carbonate has been decomposed by the hydrochloric acid, an excess of 20 ml. is added, and the liquid is heated to 34 J.A. Munch and J. Silver, op> cit.. 21 boiling. Potassium chlorate is then added to bring about oxidation, and the solution evaporated until salt separates out. At this point, more water is added, and the solution is again evaporated to insure the removal of excess chlorine. After the solution has cooled, 15 ml. of 0.10 N. sodium thio- sulphate and one gram of potassium iodide are added. The sol ution is allowed, to stand for five minutes and the thiosul- phate is then titrated with 0.10 N. iodine. Thallium contain ed in the sample may be estimated according to the following calculations: 40.000 : 508 :: ml. Na^S^Or,*5IkO : X weight of sample in grams x 100 per cent of TlgSO^ in the sample. 35 Lepper has proposed a gravimetric method for the determination of thallium based on the following procedure: Organic matter is destroyed by treatment with nitric acid and sulphuric acid in the Kjeldahl flask. After the nitric acid treatment, portions of sodium nitrate are added until a light yellow solution is obtained. The solution is then cooled, diluted with water, and brought to boil. Six per cent sulphur dioxide solution is added and the excess is removed by boiling. At this point, the solution is again diluted and then neutralized with ammonium hydroxide. Five ^W. Lepper, op. cit.. pp. 321-324 ml. of glacial acetic acid are added and the solution is filtered. One half of the filtrate is heated to 90° and thal- lous iodide is precipitated by the addition of 4 per cent potassium iodide solution. The thallous iodide is separated from the solution by filtering through the perforated crucible and thallium is determined in the precipitate. 36 Fridli , one of the first experimenters to be con fronted with the problem of the determination of thallium in toxicological materials, proposed a gravimetric method for the analysis. Briefly, his procedure consisted of the fol lowing steps: (l) Digesting the organic matter with concen trated sodium hydroxide, and igniting it over a free flame; (2) Neutralizing the cooled ash with sulphuric acid; (3) De pressing the ionization of other metals in the solution by treatment withsecondary sodium phosphate; (4) Filtering the solution to remove the flocculent ferric phosphate produced by the action of the phosphate on the iron in solution; (5) Oxidizing the filtrate with bromine water, and adding phenol to remove the excess; (6) Precipitating the thallium by the addition of potassium iodide solution; (7) Dissolving the precipitate in chlorine water; (8) Evaporating to dryness; and (9) Determining thallium in the residue. 3®R. Fridli, op. cit., pp. 478-488 DESCRIPTION OF MATERIALS AND APPARATUS In the experimental work conducted in connection with this investigation, four important pieces of apparatus were used. These included (l) a Christian Becker analytical bal ance of the chainomatic type, (&) a 50 ml. calibrated pyrex burette, (3) a 1000 ml. calibrated volumetric flask, and (4) a Lamotte roulette color comparator. Standard solutions of thallium sulphate containing 1, 2, and 4.06 mg. of thallium per milliter of solution were prepared and test samples used in the experiments, where re sults have been reported, were drawn from the prepared stan dard solutions through the calibrated burette. The toxicolo- gical material, from which thallium was extracted, were ground beef and human urine; otherwise only analyzed chemical reagents were used in reported determinations. METHODS USED AND EXPERIMENTAL RESULTS As the purpose of this investigation was to study methods for the determination of thallium in toxicological materials and to compare experimental results with those re ported by previous investigators, it was necessary to conduct two sets of experiments, those in which thallium was determin ed in simple test solutions, and those in which thallium was determined in toxicological materials. For the determination of thallium in simple test sol utions, three methods that have been reported to give the best results were experimentally investigated. The methods tested included the determination of thallium as (l) thallous chrornate, ( 2) thallous iodide, and (3) thallic oxide* For the determination of thallium in toxicological materials, two methods were tested. They were (l) a gravi metric determination based on FridliTs procedure described in detail on page 22, and ( 2) a colorimetric determination based on ShawTs procedure described in detail on page 19. Of the various methods proposed for the determination of thallium in toxicological materials, the two experimental ly tested were chosen for investigation because a prelimin ary analysis of recommended procedures showed these two to be worthy of primary consideration. In the pages that follow exact experimental procedures 25 appropriate helpful observations, and calculated experimental results will be presented in connection with each group test ed. The Determination of Thallium as Thallous Chrornate. In simple test solutions, quantities of thallium ranging in amounts from 2 to 21 mg., may be conveniently determined on thallous chromate by precipitating a warm ammoniacal solution of thallous thallium with potassium chromate. If the result ant precipitate is allowed to settle overnight, then filtered out on a previously prepared perforated crucible, washed with 1 per cent potassium chromate solution and dried for one hour periods at 100° to constant weight, satisfactory results may be obtained. Care must be taken, however, to insure the com plete removal of the precipitate from its solution, as the particles of the thallous chromate are extremely minute and there is danger that they may not all be retained by the first and second filtration. A third, fourth, and even fifth filtration is recommended if the greatest possible accuracy is to be obtained in this determination. See Table V. The Determination of Thallium as Thallous Iodide. For the determination of thallium as thallous iodide in simple test solutions, good results have been obtained by making.a solution of thallous thallium neutral to phehophthalein with ammonium hydroxide, then acidifying it with acetic acid, and. 0.0190 0.0240 0.0187 -0.0003 0.0210 0.0268 0.0209 -0.0001 JO JO JO J o JO | w* j wj j » J [ » j C Tltf^ W tO H O C O O D -C Z O iai^ C K lS O H O C O O O -^O U l^W S O H o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o Mh^WMHHHHOOOOOOOOOOOOOOO CQ-^-^CJlWCKlHHCQCO^OOUiCn^^i^WWEOSOfcO o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o • • • • • • • • • • • • • • • • • • • • • • a o o o o o o o o o o o o o o o o o o o o o o o MK)f3HHHHHHHOOOOOOOOOOOOO (^HHOOUl^WWHOCDOD-Nl^UlOiWWMWWMK) O H C D O O t^ W C ^ C J !C S lC J iH C J iO O C iD £ O C D C D < 2 0 ir O ^ (^ OOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOO jjpp(j|j|j|jjjOOOOOOOOOOOOOOO Q0(X>-3^50S0OOa)0Q-aOUiCn^^0303£02020HH -<2^ooo-3^uia>MHOcocjtcna)OOH-3CjicocQ o H* Hj 3 c+ • H001 |»J O 20 B Hj W>r3 O H H3 0 H h ! h 3 ^ ( D H c+ o£0 t o o < J h S o (D Oh 0 4 H* 0 2 c+ o • o H3 < O Hj »-sO 0 •-sH P- O H f j l s . C O t r < I t 1 o a C O o o H 3 t ? d o t ? d H 3 t d m > H - 3 M o ! 2 3 § K1 M a I I I I I I I I I I + - I - I - I - I + I I I I + I I o o o o o o o o o o o o o o o o o o o o o o o • • • • • • • • • • • • • • • • • • • • • • a o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o OOOOHOOOOOOOOOOOHHOOOOO WOO(^OWOOl50CDH<^>HCJi|^COOOc.OWCnHH I? o H TilBLE V 27 precipitating thallous iodide by the action of potassium iodide. The precipitate produced in this manner is allowed to settle 12 to 18 hours, and then separated in the Goode crucible, dried for one hour periods at 100° to constant weight and thallium determined from the v/eight of the preci pitate. See Table VI. The Gravimetric Determination of Thallium as Thallic Oxide. In the determination of thallium as the susquioxide, the procedure of Browning et al., tested in detail on page 15, was followed. Even though some good results for this method were experimentally obtained in this investigation, it is not recommended for ordinary laboratory procedure be cause the presence of carbon dioxide and other component gases of laboratory air will materially affect the accuracy of this determination unless extreme precautions are taken to prevent the possibility of their adsorption. See Table VII. The Determination of Thallium in Toxicological Mater ials bv Fridli1s Procedure. It was found by experiment that determinations of thallium by FridliTs method, reviewed in detail on page 22, fail to give trustworthy results. Of twenty-four experiments conducted under the conditions of this procedure, only four results were found to be satis factory, and it is believed that these seeming checks were entirely accidental. There are a number of factors leading TABLE VI THE DETERMINATION OF THALLIUM AS THALLOUS IODIDE Wt. of T1 Wt. of Wt. of T1 in sample Til in .Til of TlgSO4 recovered recovered 1 0.0020 0.0032 0.0020 2 0.0041 0.0076 0.0047 3 0.0061 0.0105 0.0065 4 0.0081 0.0133 0.0082 5 0.0102 0.0163 0.0101 6 0.0122 0.0183 0.0113 7 0.0162 0.0270 0.0167 8 0.0162 0.0266 0.0164 9 0.0203 0.0323 0.0199 10 0.0203 0.0332 0.0205 11 0.0244 0.0396 0.0244 12 0.0264 0.0444 0.0274 13 0.0284 0.0467 0.0288 14 0.0305 0.0491 0.0301 15 0.0325 0.0532 0.0328 16 0.0345 0.0553 0.0341 17 0.0365 0.0585 0.0361 18 0.0406 0.0654 0.0403 Error -0.0000 +0.0006 +0.0004 +0.0001 - 0.0001 -0.0009 +0.0005 +0•0002 -0.0004 +0.0002 +0.0000 +0.0010 +0.0004 -0.0004 +0.0003 -0.0004 -0.0004 -0.0003 TABLE VII THE DETERMINATION OF THALLIUM AS THALLIC OXIDE Wt. of T1 Wt. of Wt. of T1 in sample ^ 2°3 ^ 2^3 of Tl^SO^ recovered recovered 1 2 3 4 5 6 7 8 9 10 11 12 0.0020 0.0061 0.0081 0.0122 0.0142 0.0183 0.0244 0.0264 0.0284 0.0304 0.0325 0.0365 0.0019 0.0075 0.0085 0.0129 0.0153 0.0198 0.0270 0.0284 0.0322 0.0340 0.0362 0.0393 0.0017 0.0067 0.0076 0.0115 0.0137 0.0177 0.0242 0•0254 0.0288 0.0304 0.0324 0.0352 Error -0.0003 -0.0006 -0.0005 -0.0007 -0.0005 -0.0006 - 0.0002 - 0.0010 +0.0004 0.0000 - 0.0001 -0.0013 30 to difficulty in this method, chief among which are the follow ing: 1. On heating cadaveric material with sodium hydroxide a soapy product is formed. If this soapy substance is removed before proceeding with the experiment, an appreciable quantity of thallium that has been occluded in its formation is lost from the determination. If, however, this product is destroy ed by ignition, as recommended in the-procedure, the charred carboniferous material that results becomes fused to the walls of the container, making a complete transfer of this material to another container virtually impossible and rendering fur ther manipulation in the same vessel extremely difficult. 2. It was found by spectrographic analysis that the filter papers used in effecting the removal of the flocculent ferric phosphate precipitate contained thallium. Obviously, the quantity of thallium that had been withheld by occlusion was lost from the experiment, and consequently the accuracy of the determination was correspondingly lowered. In view of these difficulties, and in view of the fact that the procedure is, in general, cumbersome and time consum ing, this method is not highly recommended for the determina tion of small quantities of thallium in cadaveric material. The Colorimetric Determination of Thallium in Toxico logical Materials bv the Method' of Paul A* Shaw. Experimental 51 results reported for determinations of thallium by this method and listed in Table VIII were obtained under condi tions described on page 19. M M M > W H pq E h < O M O O o o H iq O o S h E H S pq M £3 M H Q O H H H Q • Si W H & q E h E H E H p c ; <H 73 pq O g O P Q P M • O H •P «H o E H M a §‘ E H W Q O M P C I EH *E?rf M P G O H o o H ( 1 ) ^ EH HO PtCO « h a o s O a j H m Eh if S % ^ *H 0 o o o o o ino o o ino m o ino o o o in ininino inino o o o o q ino o o o in o o o o o o o o o o o o 03o o H o o H o o o H o o C V 3H o 02H H H o o o o H o o o o o o o o o o o o o O o o O o o o o o o O o o o o o o O O O o o o o o o o o o o o o o o o o o o O o o O o o o o o o O o o o o o o O O O o o o o o o o • • • • • • • • • • • • • • • • • • • • • • • « • • • • • • • • ♦ + • • • • o + o + o o o o 1 o o o + o 1 o o 1 o o i o + o o o 1 o o 1 + o + o 1 o o 1 o 1 o 1 o o 1 o + o 1 o + o i o + o o o 1 o o 1 + o o o o o ino o o + ino ino ino o o o in inm ino m ino o o o o o ino o o o in o H 0 3tototo0 3toD OD Otoin0 3in■^itoinininto COC DCOo C D0-C Do 0 003H D Ointoz> co o o o o o o o o o o o o o o o o o o o o o O o H H o O H o H H H H H H H H H 0 3 o o o o o o o o o o o o o o o o o o o o O o o O o O o o o O O O O o O O o o • • • • • • • • • • • • • • * • • ■ • • • • • • • • • • • • • • • • • • • • • o o o o o o o o o o o o o o o o o o 0 0 o o o o o o o o o o o o O o o o o o Q o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o H 03D OtotoC OD OD OC O ininininininintoZ> C OC Do o o o o o o H 0 2C Os j lintoz>C OC D O o o o o o o o o o o o o o o o o o o o o o H H H H H H H H H H H H H H H H 0 2 o o o o o o o o o o o o o o o o o o o o o o o o O o o o O O O O o O o o O O • • ♦ « ♦ • ♦ • • • • • • • • • • • • • • * • • • • • • • • • • • ♦ • • • • o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o O o o o o o o H 0 2 t0 -^ iO C D £ > -0 0 < J ) O H 0 3 t Q ^ L 0 C D C ^ 0 0 O O H 0 3 t 0 s f » L 0 C 0 C w 0 0 C ^ O H 0 2 C 0 ^ i0 C D r > C 0 HHHHHHHHHH02 03 03 02 02 02 03 02 02 02COCQDOtQCQtQCQCOcO SUMMARY AND CONCLUSIONS In this investigation, nine methods for the quantita tive determination of thallium have been reviewed, and all known important methods for its qualitative analysis have been considered. Five of the nine proposed quantitative pro cedures reviewed have been experimentally tested and many of the suggested characteristic reactions for the identification of this element have been confirmed. From an analysis of the experimental results obtained, it appears that for the determination of small quantities of thallium in simple test solutions, the gravimetric methods based on the precipitation of thallium as thallous chromate, and as thallous iodide, described in detail on pages S5 and 27 respectively, are preferable to other suggested methods. For the determination of small quantities of thallium in toxicological materials, the colorimetric method of Shaw, described on page 19, has been found to give satisfactory results. But before it can be definitely concluded that this is the best procedure for such an analysis, the method of 37 W. Lepper must be further tested. 37 W. Lepper, op. cit. BIBLIOGRAPHY BOOKS Comey, Arthur M., A Dictionary of Chemical Solubilities. London: The Macmillan Company, 1896, pp. 469-471. Crookes, Sir William, Selected Methods in Chemical Analysis. London: Longmans, Green and Company, 1905. pp. 164-178. Gooch, Frank Austin, Methods in Chemical Analysis. New York: John Wiley and Sons, 1912, pp. 219-224. Hillebrand, W.F., and Lundell, G.E.F., Applied Inorganic Chemistry. London: Chapman and Hall, Limited, 1929. pp. 373-378.- Lindsley, L.C., Industrial Microscopy. Richmond, Virginia: The William-Byrd Press, Inc., 1929. pp. 79-82, 151, 154, 155, 157-160. Ostwald, Wilhelm, The Principles of Inorganic Chemistry. London: The Macmillan Company, pp. 689-692. Prescott, Albert Benjamin and Johnson, O.C., Qualitative Chem ical Analysis. Revised edition. New York: D. Van Nos trand Company, Inc., 1933. pp. 204-206. Scott, Wilfred W., Standard Methods of Chemical Analysis. New York: D. Van Nostrand Company, Inc., 1925. pp; 140- 141. PERIODICAL .ARTICLES Ginsburg, H.M., and Nixon, C.E., ”A report of eleven cases of thallium poisoning at the General Hospital of Fresno County, California.” Journal of the American Medical Association, 98: 1076-77, March 6, 1932. Munch, James C., Ginsburg, H.M., and-Nixon, C.E., ”Thallo- toxicosis outbreak in California.” Journal of the Ameri can Medical Association. 100: 1315-19, April 29, 1933. 35 Munch, James C., and Silver, James, BThe pharmacology of thal lium and its use in rodent c o n t r o l , Department of -Agriculture. Technical Bulletin £38, April, 1931. Kudy, Abraham, ^Severe thallium acetate intoxication caused by the use of a depilatory called Yeremin1.1 1 Hew England Journal of Medicine. 207: 1151-52, Shaw, Paul A., ? i Colorimetric determinate Industrial and Engineering Chemistr 5: 93-95, 1933. Testoni, P., HThe behavior of thallium a ism,H Archives internationales de therapie. 44: 328-351, February 15, haIlium.” .vtfcal Edition. on the organ- odvnamie et de

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Creator Summers, P. G (author)

Core Title A study of methods for the determination of thallium in toxicological analysis

Degree Master of Science

Degree Program Chemistry

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag chemistry, analytical,OAI-PMH Harvest

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Advisor [illegible] (committee chair), [illegible] (committee member), Roberts, L.D. (committee member)

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