The lithium used for the test was contained in a bottle filled with mineral oil. The metal was removed from the bottle inside a dry box containing an inert atmosphere, and the mineral oil was wiped from the lithium. Several samples weighing approximately 200 mg. were cut from the lithium and placed in small, screw-capped sample vials. These samples were added to the reactors while a rapid flow of helium emanated from the gas inlet tubes connected to the reactors and flowed around the opening of the sample vial. KO difficulty was experienced while evacuating the reactors; the reaction proceeded smoothly with no apparent undue pressure increase, and the interior of the reactor was devoid of the expected finely divided lithium
fluoride. Also, agreement between the results obtained from the replicate samplings was quite reasonable. Results from replicate analysis of two different samples of Lie are shown in Table I. While changes in sampling technique may be necessary, depending on the manner in which the sample is submitted for analysis, the KBrF4 method appears to be routinely applicable to the determination of oxygen and nitrogen, as contaminants, in lithium metal. The accuracy of the method-and the concentration range of the contaminants in the metal which can be determined-should be at least as reliable as the data for other metaIs in the original publication. The range of oxygen and nitrogen that can be measured conveniently is from 0.02 to 10 mg.
(1) Bate, L. C., Leddicotte, G. W., O R N L - ~ ~ January S~, 30, 1958. (2) Dupraw, W. A., O’Neill, H. J., ANAL. CHEM.31, 1104 (1959). (3) Gilbert, T. W.1 Jr.1 MeYer, A. S., Jr., White, J. C., ANAL.CHEM.29, 1627 (1957). ( 4 ) Goldberg, G., Meyer, A. S., Jr., White, J. c., A N A L . CHEW 32, 314 (1960). (5) PePkoffitZ,L. P., Judd, W. C.7 ANAL. CHEW22, 1283 (1950). (6) T\T. I,, steinmetZ, H.: ORNLZS70, October 15, 1958.
sax,
( 7 ) White, J. c., Ross, W. J., Rowan, R., Jr., ANAL.CHEM.26,210 (1954).
GERALD GOLDBERQ Oak Ridge National Laboratory Oak Operated by union Carbide carp. for U.S. Atomic Energy Commission
An Early Reference
Codostatic Impulse Relaxation: SIR: Since publication of our own work (2-4), on the coulostatic impulse relaxation techniques, we have become aware of mention of a similar or identical technique in the second paragraph of a paper by Barker Brief though this mention is, it leaves little doubt of the author’s recognition of the principle and virtues of the impulse approach, and suggests that Priority in its invention is due him.
LITERATURE CITED
LITERATURE CITED
( 4 ) Reinmuth, W. H., Wilson, C. E., ANAL. CHEM.34, 1159 (1962).
“Transactions of the Symposium of Electrode Processes, Philadelphia, 1959,” p. 325, John Wiley and Sons,
PAULDELAHAY Coates Chemical Laboratory, Louisiana State University, Baton Rouge, La.
InC., New York, 1961. (2) Delahay, p., ANAL. cHEM. 34, 1161 (1962). (3) Delahay, P., Anal. Chim. Acta 27, 90 (1962).
W. H. REINMUTH Department of Chemistry, Columbia University, Kew York 27, N. Y.
(1) Barker, G. C., in E. Yeager, ed.,
Modified Method for Spectrophotometric Determination of Cyanoacetic Acid in Blood Plasma SIR: A new method for the determination of cyanoacetic acid (CAA) has been reported recently by Sievert, Lipton, and Strong (1). The method has been applied to the measurement of cyanoacetic acid which appeared in the blood serum of turkeys following the administration of either B-aminopropionitrile or cyanoacetic acid. Because the color was unstable when sodium carbonate was used, the author investigated a series of inorganic compounds to stabilize the color. The best results were obtained with sodium hydroxide.
PROCEDURE
To several test tubes add measured volumes of cyanoacetic acid solutions, or aliquots of unknown solutions with 2 ml. of diazotized sulfanilic acid, and 1 ml. of sodium hvdroxide. dilute to 10 ml. with glassdiklled water, and mix thoroughly. Read the colors a t 490
Figure 1.
Stability-time
curves with sodium hyAPPARATUS AND REAGENTS
Beckman Model DU quartz spectrophotometer, with 1-cm. matched cells. Sodium hydroxide (low in carbonate, 240 grams), dissolved and made up to 1 liter with glassdistilled water. Standard cyanoacetic acid solution, 1 pg. of CAA per ml. Diazo reagent, prepared by the procedure of Sievert, Lipton, and Strong (1).
1344
ANALYTICAL CHEMISTRY
droxide CAA. 1. 2. 3. 4.
5.
pg./ml.
0.50 0.80 1.00 1.20 1.40
m,.t against a reagent blank Containing 2 ml.-of diazo reagent, 1 ml. of sodium hydroxide, and 7 ml. of glassdistilled Stability of Color. T o determine the effect of aging on the intensity of the color, once developed, the color complex was prepared under optimum
