The influence of pralidoxime mesylate on the measurement of cyanide concentrations in solutions.

Pralidoxime mesylate (P2S) can interfere with the colorimetric analysis for cyanide in solutions. Apparent increases in cyanide concentrations, related to the presence of P2S, are most marked at extreme pH values. At acid pH there is a direct interference by P2S, and at alkaline pH the P2S molecule is cyanogenic. Prompt analysis and the use of a cyanide separation technique minimizes the artifactual increase in measured cyanide concentrations. This effect is insignificant at pH 7.4.