Determination of Four Barbiturates in Pig Liver and Kidney by Gas Chromatography-Tandem Ion Trap Mass Spectrometry with Microwave Assisted Derivatization

KeyWord:barbiturates  gas chromatography¨Ctandem ion trap mass spectrometry  microwave assisted derivatization  liver  kidney  ultrasonic extraction  C18 SPE cartridge

Abstract:

      A gas chromatography¨Ctandem ion trap mass spectrometric£¨GC-MS/MS£© method was developed for the simultaneous determination of four barbiturates residues£¨e.g.barbital,amobarbital,secobarbital sodium and phenobarbital£© in pig liver and kindey.The barbiturates residues were extracted by ultrasonic assistant extraction with acetonitrile.The extracts were concentrated and redissolved by 5 mL 0.1 mol/L K2HPO4 £¨pH 7.4£©,cleaned up by C18 SPE cartridge using hexane¨Cethyl acetate£¨7¡Ã3£© mixture as eluting solvent,then derivatized with CH3 I by microwave irradiation.The methylated barbiturates were separated on a TR-5MS capillary column and detected with an ion trap mass detector.Electron impact£¨EI£© ion source operated in MS/MS mode was adopted for identification and external standard method was employed for quantification.Good linearities £¨r£¾0.99£© were obtained in the range of 5-100 ¦Ìg/L.The limits of detection£¨LOD,S/N¡Ý3£©for four barbiturates were no more than 0.65 ¦Ìg/kg in liver and 1.00 ¦Ìg/kg in kidney.The limits of quantitation£¨LOQ,S/N¡Ý10£© were no more than 2.20 ¦Ìg/kg in liver and 3.35 ¦Ìg/kg in kidney.The recoveries of four barbiturates at spiked levels of 5£¬10£¬15 ¦Ìg/kg ranged from 68% to 90% with relative standard deviations£¨RSDs£© no more than 10%.The results indicated that the method was accurate for the determination of barbiturate drug residues in animal tissues.