Validation of a simple gas chromatographic-mass spectrometric method for the determination of gamma-butyrolactone in human plasma.

A gas chromatographic-mass spectrometric (GC-MS) method is described for the determination of human plasma levels of gamma-butyrolactone (GBL) is described. The method is sensitive and simple. The plasma sample spiked with the internal standard was extracted by dichloromethane (CH(2)Cl(2)) in acidic conditions, and the concentrated organic layer was injected into GC-MS. Because of endogenous GBL in human plasma, the method used a standard calibration curve. The calibration curve was linear from 10 to 1000 ng/ml. The method has been validated for accuracy and precision with the relative error and C.V. for intra- and inter-day within 10%. GBL-spiked plasma samples stored at -80 degrees C were stable for a 3-month period. The stability of plasma samples after three cycles of freezing and thawing and of prepared samples on an autosampler for 48 h were demonstrated. Plasma concentrations of GBL before and after administration of UFT were 24.3+/-14.2 and 84.9+/-22.4 ng/ml, respectively.