ANALYTICAL CHEMISTRY
1140 Table 111. Production Applications by Direct Weight and Flame Photometer Methods % Solids Pickup Production Roll No.
Cord Latex-Baaed Type Formula 6226 Rayon GR-S/RFL 6257 Rayon GR-S/RFL 6269 Rayon GR-S/RFL 6507 Rayon BD/VPa/GR-S/RFL 5914 Nylon BD/VP/nat./RFL 5917 Nylon BD/VP/nat./RFL 5918 Nylon BD/VP/nat./RFL 6110 Cotton BD/VP/GR-S/RFL 6423 Cotton Neoprene/RFL 6743 Cotton Neoprene/RFL a BD. Butadiene. VP. Vinyl pyridine. R F L . Resorcinol formaldehyde latex.
Flame Weight photometer 7.6 7.6 6.1 7.0 6.1 9.9
8.6 9.5
5.2
7.7 10.8
hours. If latex and raw cord need not be determined, test time is approximately 2 hours. 5 . No direct weight comparisons were made on nylon, Dacron, and Fiberglas, although this method has been successfully used for determining per cent solids pickup on these synthetic textilos when treated by the various processing units involved.
5.6
7.0 6.0 10.0 8.8 9.5 5.5 8.0 11.0
tometer method is applicable to 95% of plant production and experimental development requirements. 3. The flame photometer method will give very accurate test results when representative samples of raw cord, latex formulation, and treated cord are furnished. By this method complete solutions are obtainable by digesting with nitric acid, whereas the zinc chloride method may contain incomplete portions. This necessitates a correction factor which varies with the fiber and latex treatment employed. 4. If the same cord or fabric and latex formulations are used in production, the flame photometer method can be readily adapted to control testing, because the latex formulations and raw cord need be checked only on occasion, thereby conserving time and allowing a broader testing coverage. Test time per sample in duplicate including latex, treated cord, and raw cord is 3 to 4
ACKNOWLEDGMENT
The authors wish to thank The Gates Rubber Co. for permi.sion to present this work, Ray Thoman for his valuable aid in writing this paper, Roland Kratzer for his help in preparing standard samples, and Margaret Seaman for preparation of the graph. LITERATURE CITED
(1) Barnes, R. B., Richardson, David, Berry, J. W., and Hood, L. R . , IND.ENG.CHEM.,Aiv.4~.ED.,17, 605 (1945). (2) Conrad, A. L., and Johnson, W. C., .$SAL. CHEM.,22,1530 (1950). (3) Gilbert, P. T., Jr., Hawes, R. C., and Beckman, 8. D., Ibid.,22, 772 (1950). (4)
(5) (6) (7)
(8) (9)
Gilliland. J. L., Symgosium on Flame Photometry, A S T M Spec. Tech. Pub. 116 (Varch 1952). Gillman, H. H., and Thoman, R. T., Ind. Eng. Chem., 40, 1237 (1948). Kline, Emil, private communication, April 24, 1945. Murphy, R. T., Baker, L. AT., and Reinhardt, R., Jr., Ind. Eng. Chem., 40, 2292-5 (1948). Rude, R. E., Lakeshore Tire B: Rubber Co. (now Armstrong Tire and Rubber Co.), Des Moines, Iowa, private communication, June 7, 1948. Tramutt, H. M., and Anderson, E., The Gates Rubber Co., Chem. Test Method 60, unpublished data.
RECEIVED for review September 28, 1953. Accepted May 3, 1954. Presented before the Division of Rubber Chemistry a t the 124th Meeting of the AMERICAN CHEMICALSOCIETY,Chicago, Ill.
Preparation of Carrier-Free lanthanum-1 40 M U R R E L L L. SALUTSKY and H. W. KIRBY Mound Laboratory, Miamisburg, Ohio Tracer methods for lanthanum find limited usage because of the short half life (40 hours) of the radioisotope lanthanum-140. A continual supply of carrier-free lanthanum-140 can be obtained by “milking” it at intervals of a few days from its parent, barium-140 (12.8-day half life). Barium-140 is precipitated with barium nitrate carrier from 80% nitric acid, and lanthanum-140 is recovered from the filtrate. A yield of about 90% was obtained, and high purity was indicated by the fact that the lanthanum-140 decayed with a 40-hour half life for about 15 days. By use of this method a tracer supply of lanthanum-140 is available for several weeks from an initial source of a few millicuries of barium-140. A modified filter-beaker, specially adapted for radiochemical work, is described.
T
HE determination of lanthanum in rare earth mixtures is
complicated by the difficulty of distinguishing its properties from those of other cerium earths. In fact, lanthanum is usually determined by difference after the mixture has been analyzed for other rare earth elements (4,14). -4nalytical methods based on oxidimetry, such as is used for cerium ( 2 2 ) , praseodymium ( I S ) , and europium (a), cannot be applied, because an oxidation state other than three is unknown for lanthanum (9,11). Lanthanum salts have no characteristic absorption bands in the visi-
ble spectrum; therefore, spectrophotometric methods such as Moeller and Brantley (9) and Rodden (14,15)used for many of the rare earths are not possible. Radioactive tracer methods (20)can be used for the determination of lanthanum. Lanthanum-140, a beta-emitter which decays to stable cerium-140, seems t o be the most practical isotope for tracer experiments; but, because of its relatively short half life of 40.22 f 0.02 hours ( 7 ) ,its use is limited in most laboratories. However, a continual supply of carrier-free lanthanum-140 can be obtained by “milking” it a t intervals of a few days from its parent isobar, barium-140 (6, I O ) , which has a considerahlg longer half life, 12.8 days (I), than lanthanum-140. Schweitzer and Jackson (18) separated carrier-free lanthanum140 from barium-140 by the formation of a radiocolloid of lanthanum in basic solution, The radiocolloid was filtered on a fine fritted glass filter. However, some barium-140 was carried by the colloidal lanthanum-140, and the method had to be repeated several times to obtain the desired purity. High yields were obtained only if special precautions were taken against the introduction of carbonate and the absorption of carbon dioxide. Carrier-free lanthanum-140 also has been separated by precipitation on ferric hydroxide, using barium holdback carrier to retain the barium-140 in solution (IO). This method requires a t least a double precipitation of the ferric hydroxide and a subsequent ether extraction to remove the iron. Ion exchange has been used t o prepare carrier-free lanthanum-140 (f7,19).
1141
V O L U M E 2 6 , NO. 7, J U L Y 1 9 5 4
wccessivc milkings. I t is suggested also that fresh barium nitrate be used with each new shipment of barium-140. APPARATUS MOUTH
.
L
/
300
i t--3.5crn+
Figure 1.
RIodificd Filter-Beaker
IIon ever, the authors have found that the method is too timeconsuming to be practical. In this paper a method is given for obtaining carrier-free lunthanum-140, which is based on the low solubility of barium nitiate in 80% nitric acid ( 2 , 21) as compared to the relutivrlv high qolubility of lanthanum nitrate (12). Barium-140 is precipitated n-ith barium nitrate carrier from 80% nitric acid, and ruirier-frw lmthanum-140 is recovered from the filtrate. The hnrium nitrate precipitate is set aside for a fen- days to allon lanthanum130 to groJ7 in. IJ7hen additional lanthanum-140 is needed, thc barium nitrate is dissolved and reprecipitated from 80% nitric acid. I n this way a tracer supply of lanthanum-140 is availahlr for several weeks from an initial source of a few millirurie; of I n r ium-140. REAGENTS
Barium-Lanthanum-140. Ten millicuries of barium-lanthanum-140 equilibrium mixture as the chlorides in 10 ml. of dilute hydrochloric acid solution was obtained from the Radioisotopes Division of the Oak Ridge National Laboratory. The isotopes were reported to be carrier-free. The only radioactive impurity reported was strontium-89, which was present in the millicurie per milliliter. amount of 1.44 X Nitric acid. The concentrated (7oyO)nitric acid was analytical reagent grade. The red fuming nitric acid was Baker and Adamson reagent grade and assayed 93.1% nitric acid and 7.05y0 K,O3. Barium nitrate. Reagent grade barium chloride was dissolved in water, and barium nitrate was precipitated by adding concentrated nitric acid. Impurities which were soluble in concentrated nitric acid were thus removed. The barium nitrate was filtered in a sintered-glass funnel, washed with a small quantity of water, and dried a t 110' C.
The recommended procedure can be carried out in small beakers uqing small sintered-glass funnels for the filtrations. Homver, the separation is more conveniently made in a modified filterIieaker (Figure 1). Reagents are added through the mouth with a medicine dropper. Stirring is effected with a magnetic stirrer. 1 small piece of iron wire sealed in glass makes a convenient stirring bar. Heat is supplied by an infrared lamp. Evaporation is somewhat slow, but can be speeded up by placing the filterbeaker on a piece of asbestos pad, by painting the bottom of the filter-beaker black with a suspension of colloidal graphite in water, or by passing a stream of dry warm air through the tail. For filtrations the tail of the filter-beaker is inserted into the top of a small bell jar fitted with a standard taper joint or, if nerded, into another filter-beaker. The barium nitrate, which is never removed from the filterbeaker, may be redissolved by backwashing the frit with water. This is accomplished by applying suction to the mouth and adding water through the tail by means of a transfer pipet (a medicine dropper with the dropping end drawn down to a capillary tube). The modified filter-beakers are excellent radiochemical equipment because they keep the radioactive material confined, thereby reducing contamination. They are equipped with interchangeable standard taper joints so that they may be used in vries. DISCUSSION
The purity of the carrier-free lanthanum-140 prepared by the procedure was determined by following its decay. Samples were mounted on 2-inch stainless steel disks and the beta activity was counted periodically in a Xuclear Measurements Corp. Model PC-1 proportional counter. The lanthanum-140 showed no significant deviation from a half life of 40.22 hours ( 7 ) for a t least 15 days (Figure 2). After this length of time only 0 2% of the original lanthanum-140 remained. .4n average yield of i 5 % was obtained when the separation oat: carried out in beakers, ahereas in a filter-beaker the yield was 88%. Higher yields can be obtained if the barium nitrate precipitates are washed with 80% nitric acid, but this also increases slightly the amount of barium-140 i m p u r i t y . A s h i g h p u r i t y is thought to he the more important factor, the reconimendation i p 8.0made that the precipitates not I ccommended
7.5C
RECOMMENDED PROCEDURE
Add the barium-lanthanum-140 and 0.5 gram of barium nitrate t o 2 ml. of water. Heat and stir until all the barium nitrate has dissolved. (If necessary, add a few additional drops of water). Reprecipitate the barium nitrate by the dropwise addition of 2 ml. of concentrated nitric acid. Evaporate with stirring until the volume of the mixture is approximately 2 ml. Cool in an ice bath and add 3 ml. of red fuming nitric acid. Digest in an ice bath for 15 niinutes with st'irring. Filter the 1):irium nitrate and discard the filtrate. Set the barium nitrat,e :wide for several days. After fresh lanthanum-1-40 has grown in, dissolve the barium nitrate in 2 ml. of water. Reprecipitate the barium nitrate from 8OY0 nitric acid as described above. Filter the barium nitrate, I>utdo not wash it. Evaporate t'he filtrate to dryness in a small 1)eaker (20- or 30-ml.). Dissolve the slight residue in dilute nitric acid and dilute to the desired volume. Save the barium nitrate for future milkings. One millicurie or less is a convenient quantity of bariumIanthanun~-l40to use. Larger quantities can be used with personnel shielding. The first, milking of lanthanum-140 was discarded, since this fraction contained any impurities in the original barium-140 Tvhich were soluble in 80% nitric acid. The lanthanum-140 n-hich then grows in is free of these impurities. I t is recommended that a t least 4 or 5 days be allowed between
E
r
5
7.0-
0 0 e,
0 A
6.5-
6.0-
5.5-
5.0
d
4
6
B
IO
12 14 DAYS
I
16
18
I
\ 0I
20 22
Figure 2. Decay of Lanthanum-I40 Prepared by Recommended Procedure
ANALYTICAL CHEMISTRY
1142 be washed. The remainder of the lanthanum-140 is not lost but stays with the barium-140. The quantitativeness of precipitation of barium nitrate in 80% nitric acid was determined by analyzing the filtrates for barium140 by the method of differential decay (6). The average barium concentration in the SO% nitric acid filtrates was 0.01 mg. of barium per milliliter. Since the total volume was 5 ml. and about 250 mg. of barium carrier was used, the amount of barium-140 remaining in the filtrate as a radioactive impurity in the lanthanum-140 was found to be approximately 0.03%. The recommended procedure is particularly effective for preparing carrier-free lanthanum-140 because only strontium, barium, radium, and lead form insoluble nitrates in SO% nitric acid ( 2 1 ) . Hence, the lanthanum-140 which grows in after the first milking need be separated only from these elements and their daughter activities. Radium and lead were both found to be absent, as the alpha activity in the lanthanum-140 mounts did not differ significantly from background. (All radioactive isotopes of lead and radium have alpha emitters in their decay chains.) The quantity of barium has been shown to be very log,, and the same is probably true for strontium (21). However, if exceptional purity is required ( 7 ) , the strontium activity can be separated by using a double barium chromate precipitation from homogeneous solution (16). The preparation can be carried out rapidly. The lanthanum140 can be easily recovered from the 80% nitric acid filtrate because of the very small volumes of solutions used. The entire procedure, including separation and recovery, requires less than 2 hours from the time a t which the separation from barium-140 is initiated. LITERATURE CITED
(1) Engelkemeir, D. W., Freedman, M. S., Glendenin, L. E., and Metcalf, R. P., “Characteristics of 12.8d Ba140,” Natl. Nuclear Energy Ser., IV-9, pp. 1104-07, Xew York, McGraw-Hill Book Co., Inc., 1951. (2) Greene, C . H., J . Am. Chem. Soc., 59, 1186 (1937).
(3) Gruen, D. M., Koehler, W. C., and Kata. J. J., Ibid.. 73, 1475, (1951). (4)
(5) (6) (7)
(8) (9) (10)
Hillebrand, W.F., Lundell, G. E. F., Bright. H. h.,and Hoffman, J. I., “-4pplied Inorganic Analysis,” 2nd ed., p. 560, Kew York, John Wiley & Sons, 1953. Katcoff, S., Leary, J. B . , Walsh, K. d.,Elmer, R. d.,Goldsmith, S. S., Hall, L. D., Newbury, E. G., Povelites, J. J.. and Waddell, J. s., J . Chem. Phys., 17, 421 (1949). Kirby, H. W., ANAL.CHEM.,24, 1678 (1952). Kirby, H. W., and Salutsky, M. L., Phys. Rec., 93, 1051 (1954). McCoy, H. N., J . Am. Chem. Soc., 58, 1577 (1936). Moeller, T., and Brantley, J. C., h s a ~CHmf., . 22, 433 (1950). Overstreet, R.. Jacobson, L., Scott, K., and Fisher, H., “Radiolanthanum (La19 ,” U. S. dtomic Energy Commission,
MDDC-1142A (1943). (11) Pagel, H. A., and Brinton, P. H. M.-P., J . Am. Chern. Soe., 5 1 , 4 3 (1929). (12) Quill, L. L., and Robey. R. F., Ibid., 59, 2591 (1937). (13) Quill, L. L., and Salutsky, 11.L., ANAL.CHEM.. submitted for
publication.
(14) Rodden, C. J., J . Research .YatZ. Bur. S t a n d a r d s , 26, 557 (1941). (15) Ibid.. 28. 265 (1942). (16) Salutsky, 11.L., Stites, J. G., and Nartin A. W., ANAL.CHEM., 25, 1677 (1953). (17) Schubert, J., and Richter, J. W.,“Studies on the Barium Citrate I
~I
Complex in Ammonium Chloride by the Ion Exchange Ilethod,” U. S. Atomic Energy Commission, AECD-1986 (declassified 1948). (18) Schweiteer, G. K., and Jackson, W. M.,J . 4 m . Chern. SOC.,74,
4178 (1952). (19) Tompkins, E. R., Khym, J. X., and Cohn, W. E., Ibid., 69, 2769 (1947). (20) Wahl, A. C., and Bonner, S . A , , “Radioactivity ripplied to Chemistry,” pp. 93-101, 354-92, Sew York, John Kiley & Sons, 1951. (21) Willard, H. H., and Goodspeed, E. W,, IND.ESG. CHEM., A N A L . ED.,8, 414 (1936). (22) Willard, H. H., and Young, P.. J . A m . Chem. Soc., 50, 1379 (1928). RECEIVED for review October 28, 1953. Accepted February 1 7 , 1954. Abstracted in part from MLM-889, “Preparation of Carrier-Free Lanthanum140,” Mound Laboratory, Miamisburg, Ohio, July 31, 1953. Nound Laboratory is operated by Monsanto Chemical Co. under Atoinic Energy Commission Contract .4T-33-1-GEZT-53.
Analytical Total Acid Hydrolysis of Dextrans R. J. DIMLER, H. A. DAVIS, G. J. GILL, and C. E. RlST Northern U t i l i z a t i o n Research Branch, Agricultural Research Service, U. S. D e p a r t m e n t o f Agriculture, Peoria, 111.
Information was needed on optimum conditions for complete acid hydrolysis of dextran which could be used either in determining the concentration of dextran solutions or in liberating the constituent monosaccharide units for identification. Studies of the hydrolysis of dextran and destruction of D-glucose under a limited range of hydrolysis conditions showed that, within the limitations of the measurements, essentially the same maximum yield of reducing sugars and concurrent loss of D-glucose were obtained with 2 and 4 N sulfuric acid and 1 and 2 N hydrochloric acid at 100” C. and 1N sulfuric acid at 120” C., although the point of maximum yield was attained in periods of time ranging from 50 to 180 minutes. -4bout twice the normality of sulfuric acid was required to give the same results as hydrochloric acid in terms of both time of completion of hydrolysis and rate of destruction of D-glucose. A standardized procedure is given for analytical hydrolysis employing a 0.5% solution of dextran in 4.Nsulfuric acid heated at 100’ C. for 75 minutes, the reducing power
being corrected for an approximately 4% loss of D-glucose during hydrolysis. The applicability of the procedure to different types of dextran is demonstrated. Other sets of conditions for the analytical acid hydrolysis of dextrans can be selected on the basis of these studies.
T
HE synthesis of polysaccharides by the action of microorganisms, or enzymes therefrom, has assumed increasing importance in recent years. One group of such polysaccharides, the dextrans, has been given considerable attention as a source of blood volumeexpander products. The dextrans are polymers of D-glucose and have been produced from sucrose and from starch dextrins by the use of such microorganisms as Leuconostoc mesenteroides. Some of the microorganisms also are capable of producing fructose polymers, the levans. The total acid hydrolysis of dextrans has been used as a step in the determination of the amount of polysaccharide in solution aa well as in its characterization in part by identification of the con-
