Isotope dilution mass spectrometry for procaine determination in biological samples

A simple, rapid and sensitive method for procaine determination is described. Isotope dilution mass spectrometry with (15N)procaine as internal standard was used. The analysis was performed at 4000 resolution by selected ion monitoring with temperature programming. The sample was measured in underivatized form in the direct inlet system. The method shows good analytical parameters: linearity between 0 and 40 micrograms ml-1, good precision and accuracy. The method was applied to the in vitro pharmacokinetic study of the metabolism of procaine in liver homogenates of Wistar rats. The method is rapid, permitting about six samples to be run per hour. Sensitivity of the method permits analysis at a signal-to-noise ratio of 5:1.