Table I. Determination of Amide, Urea, and Nitrile Compounds by Alkali-Fusion Gas Chromatography Conditions Analysis Standard Temp., Time, Compound theoretical deviations "C hours Acetanilide 100.5 1.5 320 0.5 Benzanilide 97.9 1.8 320 0.5 Carbanilide 98.2 1.9 340 0.5 N,N'-Dimethylcarbanilide 99.3 1.7 360 0.6 Nylon 66 98.4 2.1 360 0.5 Nylon 610 99.9 3.8 360 0.5 Polyacrylamide 98.5 3.1 300 0.3 Polyacrylonitrile 98.5 1.4 300 0.5 a Five or more determinations.
RESULTS AND DISCUSSION
Alkali-fusion results for amide, urea, and nitrile compounds are given in Table I. The temperature reported relates to the final fusion temperature. Samples were usually introduced into the furnace at ambient temperature and the final temperature was then selected. Time designates the period of fusion. Complete dissolution and fusion usually occurred within thirty minutes. A typical chromatogram of a single compound after fusion is shown in Figure 1 . The chromatogram shows two peaks, water, which is associated with the fusion reagent, and the resultant amine or ammonia. Analysis of compounds investigated by alkali-fusion gas chromatography gave results which were in excellent agreement with the theoretical amide or nitrile content based on liberated amine or ammonia. Determinations of anilides and carbanilides were within 2.1 of the theoretical predicted values with an average stan-
dard deyiation of 1.8 %. Fusion makes possible a rapid determination of amide content (primary, secondary, and tertiary) as compared to conventional alkaline hydrolysis. Polyamides, where the amide groups are links in the polymer chain were amenable to analysis by alkali-fusion. Quantitative results were obtained for Nylon 66 and Nylon 610 in less than one hour. By introducing these materials into the furnace at l 5OoC,instead of ambient temperature, reaction time can be decreased. Polymers with pendant amide groups on the polymer backbone and polymeric nitriles are also amenable to determination by fusion. Polyacrylamide and polyacrylonitrile liberated ammonia quantitatively. Fusion provided drastic enough conditions to completely react these compounds. The alkali-fusion reagent contained enough water to convert the nitrile to the amide. Upon further reaction, the reagent converts the amide to ammonia and a carboxylic acid-salt. Fusion was found to be rapid. Coupled with gas chromatographic detection, total determination and separation of mixtures are possible. It is felt that sample blends and copolymers composed of amide, nitrile, and/or ester functional groups (ix.,butadiene/acrylonitrile rubbers) may be determined without prior separation. Extension of alkali-fusion gas chromatography should result in a rapid analysis for some carbonates, polyureas, and polyurethanes. ACKNOWLEDGMENT
The authors thank Charles Meade of the University of Massachusetts who performed the elemental analyses mentioned in this paper. RECEIVED for review March 20, 1972. Accepted May 14, 1972. This work was supported by the National Science Foundation under Grant G P 28054.
Separation of Barium-140 and Lanthanum-140 by Isotopic Exchange Using Impregnated Paper Chromatography Mitchell L. Borke and Nina Y. Liang Duquesne University, Pittsburgh, Pa. 15219 MANYSPECIFIC METHODS have been developed for the separation of radioactive equilibrium mixture of 140Ba and 140La. They include the use of ion exchange resins ( I , 2 ) carboxymethyl-cellulose filter paper (3), thin layer chromatography (4), and thin layer electrophoresis (5). (1) K. B. Zaborenko, I. C . Bogatyrev, and N. L. Malgina, Radiokhimiya, 8,352 (1966). (2) K. H. Lieser and K. Baechmann, Fremenius' Z . Anal. Chem., 225, 3979(1967). (3) D. Klockow, Talunta, 15,543 (1968). (4) M. Yasuyuki, T. Kasuyuk, and M. Yukio Kanagawa-Ken Kogyo Shikensho Kenkyu Hokoku, 20, 41 (1968); Chem. Abstr., 70,16309~(1969). ( 5 ) M. Itsuhiko, T. Noriko, and S . Masaki, Yakuguku Zasski, 89, 1669(1969); Chem. Abstr., 72,62423k(1970). 2080
Until now, no application of the isotopic exchange reaction to the separation of 140Ba and 140Lahas been reported. In this investigation, the isotopic exchange reaction coupled with thin layer chromatography afforded a simple and relatively rapid separation of carrier-free I4OLa from its parent InoBa. By using an equilibrium mixture of 140Baand l40Laon barium sulfate impregnated filter paper and developing with dilute sulfuric acid-dioxane solvent system, 140Ba was retained at the point of application while 140La advanced upward almost to the solvent front, so that a clear separation was obtained. EXPERIMENTAL Chromatography paper strips, Whatman No. 1, 40 cm long, were soaked in a saturated barium chloride solution for 2 hours, then removed from the solution and dried in air.
ANALYTICAL CHEMISTRY, VOL. 44, NO. 12, OCTOBER 1972
’Ol
D I S T A N C E (cm)
DISTANCE (cm)
140
LO
S.f.
DISTANCE (cm)
DISTANCE (cm)
Figute 1. Effect of developing agent on the chromatographic behavior of 140Ba and 140La
Figure 2. Effect of sample spot drying time on the chromatographic behavior of 140Ba and lroLa.
0.1N H2S04. (b) 9 parts 0.1N %SO4 s.f. = solventfront (a)
+ 1 part 1,Cdioxane.
The dried filter paper strips were sprayed with 0.1N sulfuric acid solution using an aerosol spray kit, and again dried in air. A 5-pl sample of approximately 1 M HC1 containing the 140Ba and 40La radioactive equilibrium mixture (C.F.) was applied an inch from one end of the paper strip, and a line was drawn with a pencil at a distance of 25 cm from the point of sample application. The spot was dried in air for 1 hour and then developed by the ascending technique with a solvent system consisting of 9 parts of 0.1N sulfuric acid and 1 part of 1,4-dioxane. When the solvent reached the pencil line, the paper was removed from the chamber and allowed to dry in air. I40Ba and 140La were detected by scanning of the chromatogram and detecting the corresponding radioactivity. The radiochromatogram scanner was equipped with a windowless Geiger-Muller detector with an adjustable slit set of 0.5 mm. Location of the 1 4 0 L a spot was confirmed by exposing the dried strips to ammonia fumes, then spraying with a 0.5x alizarin in ethanol and finally with 5x acetic acid solution. The sprayed chromatogram showed a purple spot (due to Laa+)near the solvent front on a yellow background (due to Ba2+).
(a) 30 minutes.
(b)1 hour. s.f. = solvent front
bility with 0.1 N H&04. By using a solvent system consisting of 9 parts 0.1NH2S04and 1 part 1,4-dioxane, both “leading” and “tailing” were significantly decreased (Figure 1). The drying time of the applied sample affected the extent of isotopic exchange and, consequently, the quality of separation improved and the ‘‘leading’’ effect of the barium spot decreased with the increase in the sample spot drying time (Figure 2). There was no significant improvement in these phenomena when the drying time was extended beyond 1 hour. Undoubtedly, isotopic exchange between the stable and radioactive barium ions in the solid phase reached equilibrium by 1 hour. In spite of the solubility of BaS04 in H N 0 3 and in HC1, either acid (0.1N)could be satisfactorily substituted for €&SO4 in the developing system, yielding R, values of 0.84-0.89 for lanthanum. RECEIVED for rekiew March 24, 1972. Accepted May 25, 1972.
RESULTS AND DISCUSSION
Under the described experimental conditions, 40Ba was retained by isotopic exchange at the point of sample application, while 140Lamoved upward with the solvent front, showing an R, value of approximately 0.86. Preliminary experiments indicated that 0.1NH & 0 4 was more satisfactory as the developer than either 0.01N or 1 N H2S04. Since the chromatogram showed some “leading” of the barium spot and “tailing” of the lanthanum, it was decided to incorporate a small amount of a nonpolar liquid in order to decrease both these effects. 1,4-Dioxane was chosen because of its misci-
COR RECTlON Improved Tissue Solubilization for Atomic Absorption In this paper by Andre J. Jackson, Leslie W. Michael, and Herbert J. Schumacher [ANAL.CHEM., 44, 1064 (197211, the middle initial of the second author appeared incorrectly as M .
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