The effect of storage upon cyanide in blood samples

CDPA blood of human origin was 'spiked' with a solution of potassium cyanide at four different concentrations. When such blood was left in contact with the atmosphere for up to 10 min an appreciable amount of the cyanide was lost. Stoppered tubes containing the 'spiked' blood were stored at -20 degrees C and 4 degrees C for up to 6 months. Most samples, especially those 'spiked' at the highest concentrations, showed a loss of cyanide.