Anal. Chem. 1984, 56,113-116
113
micellar solutions would be useful for studying chemistry of micelles as well as for analytical purposes. Further extensive investigations are being continued to develop the possibilities of this technique.
ACKNOWLEDGMENT We thank T. Nakagawa who has proposed the application of solubilization by micelles to chromatography and H. Jizomoto for their helpful suggestions and discussions.
4
LITERATURE CITED
2
(1) Nakagawa, T. Newsl., Dlv. Colloid Surf. Chem., Chem. SOC.Jpn. 1981, 8 , No. 3, 1. (2) Nakagawa, T.; Tori, K. Kolloid 2.Z.Polym. 1964, 194. 143-147. (3) Armstrong, D.W.; Nome. F. Anal. Chem. 1981, 53, 1662-1666. (4) Mikkers, F. E. P.; Everaerts, F. M.; Verheggen, Th. P. E. M. J. Chromatogr. 1979, 189, 11-20. (5) Jorgenson, J. W.; Lukacs, K. D. Anal. Chem. 1981, 53, 1298-1302. (6) Rlce, C. L.; Whitehead, R. J. Phys. Chem. 1985, 69, 4017-4024. (7) Karger, B. L.; Snyder, L. R.; Horvath, C. “An Introduction to Separation Science”; Wiiey: New York, 1973; Chapter 5.
I
0.004a.u.
1
6
1
I
1
0
1
2 5 10 Capacity factor
I
0
5
I
I
10 Time, min
I
I
I
,
20 50
I
I
15
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Figure 2. Chromatogram by electrokinetic separatlon Indicating the total range of elution: (1) methanol, (2) phenol, (3) p-cresol, (4) 2,6xylenol, (5) p-ethylphenol, (6) Sudan 111; total tube length, 650 mm; tube length from the Injection end to the detector cell, 500 mm; total applied voltage, ca.20 kV; current, 33 P A detection wavelength, 220 nm. Other conditions are the same as In Figure 1.
employed for preparative purposes in electrokinetic separations. The use of a surfactant solution in an aqueous organic solvent will expand the applicability of this method to water-insoluble compounds. Electrokinetic separations with
Shigeru Terabe* Koji Otsuka Kunimichi Ichikawa Akihiro Tsuchiya Teiichi Ando Department of Industrial Chemistry Faculty of Engineering Kyoto University Sakyo-ku, Kyoto 606, Japan
RECEIVED for review July 8, 1983. Accepted September 19, 1983.
Electrodeposition of Actinides in a Mixed Oxalate-Chloride Electrolyte Sir: The increasing number of analyses of environmental and biological samples along with a greater need for more sensitivity have made almost impossible demands upon electrodeposition procedures. Electrodeposition has virtually become a requirement for high-quality isotopic identification and quantification of the a-emitting actinides, often under the most severe conditions. Increased sensitivity requires larger samples, and this, short of extensive separations, means more impurities during deposition. Because most deposition procedures are extremely sensitive to hydrolytic losses, even microgram amounts of impurities can cause problems with yield and reaolution. However, by merely increasing the acidity immediately prior to the beginning of the deposition, losses have been substantially decreased, and the tolerance to impurities has been improved for all the actinides without the addition of hydrofluoric acid as previously required (I). Previously, the pH was adjusted by addition of ammonium hydroxide and hydrochloric acid to a pH of about 4 using methyl red indicator. To eliminate this pH adjustment and the possibility of local hydrolysis around the drops of ammonium hydroxide, the sample is dissolved in a preadjusted electrolyte. A final pH adjustment is made with hydrochloric acid to a pH of -1.6-1.8, the salmon pink end point of thymol blue indicator. To ensure complete dissolution of extremely
hydrolytic nuclides such as protactinium and thorium, the sample, in sodium acid sulfate crystals, is heated in a hydrochloric acid-sulfuric acid mixture to sulfuric acid fumes just before deposition. The above-named changes markedly improved the reliability of all of our actinide analyses.
EXPERIMENTAL SECTION Apparatus. Early depositions were made with an Eberbach electroanalysis apparatus modified to maintain a constant preset current, with the motor replaced to reduce the speed of the anode to about 30 rpm. Subsequent depositions were made with an apparatus designed and fabricated in our own laboratory with characteristics similar to the Eberbach apparatus. The 20-mm i.d. glass cells described in a prior publication (I) are no longer available and have been replaced with disposable polyethylene cells molded in our laboratory. The brass bases and polyethylene collars have been modified to accommodate the new cells. A water-cooling jacket is no longer required in the base as the brass holder on the apparatus is water cooled and serves as a heat sink as well as an electrical conductor. The platinum anode and stainless steel disks are the same as before. The stainless steel disks are boiled in 16 M nitric acid for about 5 min, rinsed with distilled water, blotted, and air-dried. The a-emitting nuclides were deposited from solutions of approximately 2 x lo4dpm and were counted for 10 min by alpha scintillation as described by Sill ( 2 ) . a-energy analyses were obtained with a 450-mm2solid-
This article not subject to U.S. Copyright. Published 1983 by the American Chemical Society
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ANALYTICAL CHEMISTRY, VOL. 56, NO. 1, JANUARY 1984
state surface barrier detector in conjunction with a 400-channel pulse-height analyzer. All y counting was done in a 3 by 3 in. thallium-activated sodium iodide well crystal for 5 min on solutions of approximately lo4 cpm to give an error of
