Measurement of Chioroprocaine and Procaine in Plasma by Flame IonizationGas-Liquid Chromatography

procedure developed for measuring procaine and chlo-roprocaineinplasma.The unchanged drug is extracted into toluene from alkalinized plasma,togetherwith an internal standard. The solvent is removed, the residue redissolved in methanol, and aliquots are injected into a 91.5-cm gas-liquid chromatographic column containing 3 % OV-210. Sensitivity of detection is in the nanogram range. Procaine (Novocain#{174},Winthrop) and 2-chloroprocaine (Nesacaine#{174},Pennwalt), both ester-type local anesthetics, are becoming more widely used clinically because they are rapidly hydrolyzedin the blood by cholinesterase and pseudocholi-nesterasenzymes, with a consequent decreased toxicity (1). These compounds are chemically very similar, differing only by the addition of a chloride group to the basic procaine structure to obtain chloroprocaine. As the biological half-lif