Recently Farmer and Abt' described a method for the determination of the reduced ascorbic acid in the blood plasma. Briefly, the procedure consists in deproteinizing the blood plasma with tungstic acid and titration with 2 :6 dichlorphenolindophenol. They reported that the values obtained by this method parallel the intake of vitamin C and are an accurate index of the nutritional state relative to vitamin C. We have made many determinations of the reduced ascorbic acid in the blood plasma using essentially the technique of Farmer and Abt. We find it rapid and reliable and our data lead us to concur with their opinion of its significance.It is the purpose of this communication to present briefly some of our own studies which indicate that the plasma level of reduced ascorbic acid is an accurate index of the immediate nutritive level with regard to vitamin C and in health parallels the intake of the vitamin. Equally convincing data in studies of rheumatic fever and rheumatoid arthritis is reported separately. With very few exceptions our study is based upon p s t absorptive blood specimens. All data presented refer to the ascorbic acid in the blood plasma present in the reduced form.Iizfiuence of Simll a i d Large Doses of L'itnilziiz C upon Plasma Lcwls. The plasma ascorbic acid levels of 7 apparently normal adults were determined before and after ingestion of 6 oz. of orange juice. The results, which are summarized in Table I, show an appreciable rise of the plasma level 2 to 4% hours after the administration of this relatively small dose of vitamin C. The increases ranged from 15% to 69%. For this reason we believe that fasting blood specimens are essential for comparative data.In Fig. 1, the plasma ascorbic acid curves of 4 individuals who received large doses of ascorbic acid (0.5 ,om. per 100 lb.) are shown. The curves are similar in type to those for blood sugar with ~ * This work was aided by a donation from the California Fruit Growers Ex-We are indebted IFarmer, C. J., and Abt, A. F., PROC. SOC. EXP. BIOL. AND MED., 1935, 32, change and by tlie Christine Breon Fund for Medical Research.to Roffmann-La Roche, Inc., for supplies of ascorbic acid.
From the Pharmaco1o;gical La'boratorg, University of CaZif0mk.z Medical School, Salt Fran&co, Odif o m b .In the use of gum acacia in the treatment of nephrosis it is important to maintain a definite minimum concentration in the blood stream in order to derive satisfactory results. There is, therefore, need of a method for an accurate quantitative estimation of acacia on a sufficiently small sample of Wood so that the test may be frequently repeated, especially when small children are involved. Acacia is a pentosan and all the methods now employed are based on the production of furfural by heating with dilute acid, steam distilling the furfural and determining it either by weighing as the phloroglucidel or by forming a color-complex between furfural and analine acetate.' Both methods require samples too large to make them practical for this purpose. Another method based on the Shaff er-Hartmann procedure for the determination of reducing sugars freed by hydrolysis of the Folin-Wu filtrate, as suggested in a personal communication from Dr. Hartmann, is some improvement. We have, used this procedure on duplicate samples for comparison with a new spectroscopic method which we present herewith.Our method is essentially a reversal of the Pettenkofer test for bile salts, with conditions so arranged as to make it quantitative for furfural. The details are as follows: 0.5 to 1.0 cc. of blood is precipitated according to the standard Folin-Wu technic. Five-tenths to 2 cc. of the filtrate, sufficient to contain 0.5 to 1.0 mg. of acacia, is pipetted into a 10 cc. volumetric flask with enough distilled water added to give a total volume of 2 cc. ; and then 2 cc. of 80% sulfuric 1 Meek, W. J., and Gasser, H. S., Am. J.
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