Determination of acetylsalicylic acid and salicylic acid in plasma

Abstract

A specific and sensitive method has been developed for the determination of acetyl‐salicylic acid and salicylic acid in plasma. Both of these compounds are extracted from acidified plasma with ether. A portion of the ether extract is concentrated, reacted with a silanizing reagent in carbon disulfide, and the silyl derivative of acetylsalicylic acid is analyzed by gas‐liquid chromatography using dibutyl maleate as the internal standard. Another portion of the ether extract is extracted with phosphate buffer and the salicylate read spectrophotofluorometrically. Only 0.5 ml. or less of plasma is required for analysis and one can readily determine 0.4 mcg. acetylsalicylic acid/ml. in the presence of 100 mcg. salicylic acid/ml. Copyright © 1967 Wiley‐Liss, Inc., A Wiley Company