Effect of Addition of KCN to Whole Blood on Indophenol-reducing Power of Plasma

Abstract

Pijoan, Townsend and Wilson 1 noted a considerable loss of vitamin C in blood serum done by the Farmer and Abt 2 method. Pijoan and Klemperer 3 reported that this loss could be prevented by the immediate addition of M/50 KCN to the blood. In order to determine the difference in the concentration of vitamin C in blood with and without KCN, the following experiments were done. Forty cc. of venous blood were drawn and placed immediately in an Erlenmeyer flask containing 8 drops of a 20% solution of potassium oxalate. The specimen was shaken gently and divided into two equal fractions, to one of which (B) were added 8 drops of 10% KCN resulting in an M/26 solution of KCN. Both fractions (A and B) were then immediately centrifuged and the plasma drawn off. The separated plasma from each fraction was divided into four 2 cc. portions. One of each of these samples (₀ and ₀) was precipitated immediately, using 2 cc. of plasma, 4 cc. of redistilled water and 6 cc. of a 10% solution of metaphosphoric acid. These samples were then centrifuged for 5 minutes and the filtrate decanted off. Three cc. samples of the filtrate were used for the titrations, which were done by the Farmer and Abt modification of the Tillman's method. 4 The remaining 6 plasma specimens (3 with KCN and 3 without KCN) were placed in the icebox and determinations of the vitamin C content were done after intervals of approximately 30, 90 and 160 minutes as shown in the chart. The first determinations, in this experiment, were done 45 minutes after the blood was drawn. This represents the maximum time required for preparing the filtrate; the average time taken in other experiments was 25 minutes.