Abstract
Conclusions
The use of potassium cyanide as recommended in plasma ascorbic acid analyses does not necessarily invalidate the results and may cause no error. Certain lots of potassium cyanide may decolorize 2-6-dichlorsphenolindophenol, the decolorizing power of a particular lot depending upon the concentration of the salt and the pH of the dye-salt solution. Reduced ascorbic acid is stable in whole blood or metaphosphoric acid plasma filtrates for as long as 24 hours. There is a significant loss of reduced ascorbic acid when plasma stands at room temperature for more than 4 hours. This loss is not prevented by the presence of potassium cyanide in concentrations recommended in plasma ascorbic acid analysis. These observations indicate that there is no reason for the addition of potassium cyanide in the determination of plasma ascorbic acid by the methods mentioned.
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