DIURNAL CHANGES IN PLASMA-LEVELS OF 2-PYRROLIDINONE DETERMINED BY ISOTOPE-DILUTION MASS-SPECTROMETRY

A new capillary gas chromatographic method with mass spectrometric detection for the determination of 2-pyrrolidinone was developed. Using quantification based on stable isotope dilution mass spectrometry by monitoring selected ions in the ammonia chemical ionization mode diurnal changes of 2-pyrrolidinone levels in plasma of three healthy adults were established. Although substantial fluctuations, ranging from 5 to 30-mu-g/l, occurred during a 24-h daytime period, no consistent picture related to clock time or food intake was obtained. Endogenous oscillations should be taken into consideration, for example when evaluating transdermal penetration of 2-pyrrolidinone, used as enhancer in topical drug formulation