rine, in the entire concentration range studied. Two organic. standards were also prepared froin dihenzyl sulfide, monocliloroacetic acid, and potassium chloride, and :tnalj-zecl quantitatively to check the acc*uracy of the experinient>al nicthod. .l(wptnhle recoveries were obtained in all cases (Tahle 111). I n addition to thc analysis of catalysts, t,he nirt,hod is applicable to engine deposits, big!) boiling oils. and organic chemicals. Sulfur-Bromine. Several purc' rompourids \!-we blended t o ohtnin aamplc,s of knon-n concentrations of both sulfur and bromine. Dibenzyl sulfide (Ehstnian Kodak Co.), and calcium and potassium sulfate were used a s t h e source of sulfur. Potassium bromide a n d bromate were t h e bromine standards. Mixtures of these materials were prepared quantitatively and analyzed by this method (Table
IV\. The niethod has been applied to the analysis of catalysts and engine deposits (Tahle IV). I n the latter case, !vet chemical methods are extremely complicated and uncert,ain. Repeatability averaged +0.03% on sulfur a t the I .0% level and 10.07% on bromine a t the 5 t o 1075, level.
LITERATURE CITED
(1) Agazzi, E. J., Fredericke, E. M., Brooks, F. R., ASAL. CHEM.30, 1566
(20) Koltlioff, I. M., Harris, IT. E., ISD. ESG. CHEX., ANAL.ED.18, 161 (1946). (21) Laboratory Equipment Corp., Leco Method for Sulfhr Determination rom-
(1958).
( 2 ) Agazzi, E. J., Parks, T. II.>Brooks, F. R., Ibid., 23, 1011 (1951). 1 3 ) Baker. I3. B.. hlorrison. J. D.. Ibid.. 27, 1306 (1955)'. (4) Bennet, E. L., Zbid., 26, 426 (1954). ( 5 ) Brunner, A. J., Matson, F. R., IND. ENG.CHEM.,A ~ LED. . 19, 156 (1947). (6) Caston, C. R., Saylor, J. H., A s . 4 ~ . \
,
CHEII.24,1360 (1952).
( 7 ) Chilton, J. ll., Horton, A. D., Zbid.,
27,842 (1955).
(8) Chu, Chin-Chen, Schnfer, J. J., Ibid.,
27, 1429 (1955).
(9) Coller, 11.E., Leininger, R . K.: Zbid.,
27.949 11955). (10) 'Eger,' Chaini, 'I-arden, Asher, Ibid., 28,512 (1956). (11) Erickson, C., Petrol. Processing 9, 1087 (1954). (12) Frieir, H. E., Sippoldt, B. W., Olson, P. B., Weiblen, D. G., ANAL. C H E ~27,146 I. (1955). (13) Gaylor, V. F., Conrad, A. L., Landerl, J. H., Zbid., 29,224 (195i). (14) Gerhardt, P. B., Dyroff, G. V., Ibid., 28, 1726 (1956). (15'1 Grant. C. L.. Haendler. H. 11..Zbid.. 28.415 (i956). ' (16) 'Grimaldi, 'F. S., Ingram, Blanch, Cuttitta, Frank, Zbzd., 27, 918 (1955). (17) Gwirtsman, Joseph, Mavrodineanu, Radu, Coe, R. R., Ibid., 29, 887 (1957). (18) Holler, A. C., Klinkenberg, Rosemary, Zbid., 23, 1696 (1951). (19) Kaufman, Samuel, Zbid., 21, 582 (1949).
(24) Sicksic, S. W.,Fade!-, L.' L.,Zbid., 30, (1958). (25) Onstott, E. I., Ellis, W. P., Ibid., 28,393 (1956). (26) Petron-, H. G., Xnsh, L. K.) Ibid., 22, 1274 (1950). (27) Popov, A. I., Iinudson: C.: E., Zhid., 26, 892 (1954). ( 2 8 ) Remmert, L. F., Parks, T. I).; Ibid., 25,450 (1953). (29) Shaw, IT. RI., I h i d . , 26, 1212 (1954). 130) Shoemaker. C. E.. I b i d . . 27. 552 (1955). (31) Slioolery, J. S . , Ibid., 26, 1400 (1954). (32) Sweetser, P. B.,Zbid., 28, 1766 (1956). (33) Teston, Rebecca, RIcKenri:i: F. E., Ibid., 19, 193 (194i). (34) Wayman, D. H., Ibid., 28, 865 (1956). ( 3 5 ) Thite, T. T., Penther, C. J., Tait, P. C.. Brooks. F. P.. Ibid.. 25. 1664 (i953j. (36) Willard, H. H., \Tinter, 0. B., I N D . ESG. CHEX., h A L . ED.5 , 7 (1953). I
,
RECEIVEDfor review June 26, 1958. Accepted October 30, 1958. Group session on Analytical Research, 23rd midyear meeting of The Division of Refining, Smerican Petroleum Institute, Los .kngeles, Calif, May 1958
Reduction of Thallium(lll) to Thallium(1) with Metallic Reductors R A M O N F. ROLF' and ELMER LElNlNGER Kedzie Chemical laboratory, Michigan State University, East laming, Mich.
,Reducing columns of metallic bismuth, cadmium, or silver may b e used to reduce thallium(lll) to thallium(1) in dilute sulfuric acid solution.
A
FOR A METHOD to determine total thallium in solutions containing both thallium(II1) and thallium(1) ions revealed little information on the use of metals for the reduction of thallium(II1) to thallium(1). The most commonly used reductant is sulfur dioxide, b u t the removal of the excess reducing agent is tedious. The use of a metallic reductor coupled with a titrimetric oxidation procedure should yield a rapid and desirable scheme for the determination of total thallium. For this reason the action of various metal SEARCH
1 Present address, Dow Chemical Co., Midland, hlich.
reductors toward thallium(II1) was investigated. ks the titrimetric oxidation with standard potassium bromate solution appears to be the most satisfactory oxidation method ( I ) , the potentiometric modification ( 2 ) was chosen to determine the thallium(1) in the reduced solutions. SOLUTIONS
Standard Thallium. d 54-gram quantity of thallium(1) nitrate (Fisher Scientific Co.) was dissolved in 900 ml. of 1N sodium hydroxide solution a n d treated with 350 ml. of 5.25y0 sodium hypochlorite solution (commercial Clorox). T h e thallium(II1) oxide precipitate was washed twice b y decantation, then was dissolyed in 220 ml. of concentrated sulfuric acid a n d diluted t o 4 liters. T h e final solution was approximately 1.8X in sulfuric acid.
Aliquot portions of the solution were reduced with sulfur dioxide; the excess sulfur dioxide was removed b y boiling and the total thallium was determined by the potentiometric bromate procedure ( 2 ) . The solution contained 0.01066 gram of thallium per ml. A direct titration with bromate, omitting the prior reduction with sulfur dioxide, showed that approximately 3.5% of the thallium was present as thallium(1). Potassium Bromate. Prepared from Mallinckrodt analytical reagent grade as 0.10005 (0.01667M). REDUCING COLUMNS
Borosilicate glass columns (G. Frederick Smith Chemical Co.) , commonly used for preparing silver reductors, were filled with the following metals to give a n 18- to 20-cm. depth of the metal after first placing a plug of glass wool in the bottom. Cadmium. Filings obtained from cadVOL. 31, NO. 3, MARCH 1959
* 425
Table I.
Reduction of Thallium(lll) to Thallium(1) K O . of
Detns.
Reductor Cadmium
5 5
7 a
Bismuth
4 4 4 4 4 3 2 5
Silver
mium rod (Fisher Scientific Co.) were washed with lil' hydrochloric acid and then with 1N sulfuric acid. Bismuth. The chunk metal (Fisher scientific Co.) was crushed and the coarse pieces were sorted out. Silver. Granular silver (G. Frederick Smith Chemical Co.). The columns were washed nith 1K sulfuric acid and kept filled n i t h 0.01N sulfuric acid when not in use. PROCEDURE
Measured aliquots of the standard thallium solution were treated to give sulfuric acid concentrations from 0.1 to l.O*V and total volumes of 50 to 100 ml. Each solution was uassed through the
\Tit11 jo-ml. portions of 0.1N sulfuric acid. To the solution and washings
T1, Mg. Found, av. 31.9 5'2.9 106,3 212.7 32.0 53.1 106.4 213.1 32.0 53.0 106.5 106.5 212.8 213.1
Taken 32.0 53.1 106.4 212.8 32.0 53.1 106.5 212.8 32.0 53.1
Std. Dev. 0.22 0.33 0.20 0.40 0.10
0.17 0.25 0.39 0.11 0.10 0.14 0.44
was added 40 nil. of 6-Y hydrochloric acid. The thallium(1) lyas titrated potentiometrically with 0.1000A7 potassium bromate using the Fisher Titrimeter with a platinum-calomel electrode pair* Blanks were run on the reductors with the above procedure, but substituting 50 nil, of l,oLvsulfuric acid for the thallium solution. The correction, in terms of milliliters of 0.1s potassium bromate, was 0.02 ml. for the bismuth, 0.03 ml. for the silver, and 0.05 ml. for the cadmium reductor. After the blank correction was deducted, the results shown in Table I were obtained.
small but may vary from lot to lot, depending upon the purity. The results obtained with silver compared favorably n ith those obtained a i t h bismuth or cadmium. Upon addition of hydrochloric acid, a precipitate of silver chloride is obtained. Although the results do not indicate any loss of thallium chloride by coprecipitation with the silver chloride, the use of the bismuth or cadmium reductors is considered more convenient. K h e n bismuth or cadmium is used, thallium(1) chloride, formed upon addition of hydrochloric acid, disappears as the titration proceeds. I n the ease of silver, the silver chloride remains, and there is no visible rridence that the thallium chloride has been completely oxidized. This is not a criticism of the reduction by silver, but rather a limitation of the bromate method, which requires the addition of hydrochloric acid. Other reductors studied were lead, aluminum, zinc, amalgams of zinc, cadmium, lead, and bismuth. S o n e of these proved satisfactory. Sickel reduced the thallium quantitatively but the blanks nere high and erratic. A better grade of nickel metal nould probably serve satisfactorily. LITERATURE CITED
DISCUSSION
(1) Anderson, J. R. A,, rlx.4~.CHEBI.2 5 , 108 (1953). (2) Zintl, E., Rienacker, G., 2. anorg Chem. 153, 276 (1926).
bismuth, cadmium, or silver. The blank corrections for these metals are
RECEIVEDfor revieTY January 17, 1958. Accepted October 27, 1958.
Use of DinitrosaIicyIic Acid Reagent for Determination of Reducing Sugar GAIL LORENZ MILLER Pioneering Research Division, Quarfermasfer Research and Engineering Center, Natick, Mass.
b Rochelle salt, normally present in the dinitrosalicylic acid reagent for reducing sugar, interferes with the protective action of the sulfite, but i s essential to color stability. The difficulty may be resolved either b y eliminating Rochelle salt from the reagent and adding it to the mixture of reducing sugar and reagent after the color i s developed, or b y adding known amounts of glucose to the samples of reducing sugar to compensate for the losses sustained in the presence of the Rochelle salt. The optimal composition of a modified dinitrosalicylic acid reagent is given. 426
ANALYTICAL CHEMISTRY
*T
HE D I N T R O S A L I C Y L I C ACID REAGENT,
developed b y Sumner and coworker (11-14 for the determination of reducing sugar, is composed of dinitrosalicylic acid, Rochelle salt, phenol, sodium bisulfite, and sodium hydroxide. According to the authors of the test, Rochelle salt is introduced to prevent the reagent from dissolving oxygen (12); phenol, to increase the amount of color produced and to balance the effect of phenol encountered in urine ( I S ) ; and bisulfite, to stabilize the color obtained in the prescnce of the phenol ( I S ) . The alkali is required for the reducing action of glucosc on dinitrosalicylic acid.
The major defect in the test is in the loss of part of the reducing sugar being analyzed. This was pointed out by Sumner (12, 1 4 , was referred to by Brodersen and Ricketts (Z), and has been observed repeatedly in this laboratory (6, 8, 9). Evidence of loss of sugar is also given by the data of Hostettler, Borel, and Deuel (4) and of Bell, hlanners, and Palmer ( 1 ) . As this defect appears never to have been fully remedied, the present study was carried out to investigate the different factors which might cause it. I n the course of the investigation, the effects of varying the concentrations of the
