Gas-liquid chromatographic estimation of lignocaine, ethylglycylxylidide, glycylxylidide and 4-hydroxyxylidine in plasma and urine.

Abstract

Abstract Gas-liquid chromatographic methods have been developed for the estimation of lignocaine and its metabolites ethylglycylxylidide (EGX), glycylxylidide (GX) and 4-hydroxyxylidine in plasma and urine. Lignocaine, EGX and GX were extracted from alkaline solution, the metabolites were acetylated and the three compounds were chromatographed simultaneously using single column temperature programming with a nitrogen-sensitive flame ionization detector. The limits of detection were 10–30 ng ml−1. Conjugated 4-hydroxyxylidine in urine was hydrolysed with glusulase and chromatographed as the acetyl derivative.