Microextraction by packed sorbent coupled with gas chromatography-mass spectrometry: application to the determination of metabolites of monoterpenes in small volumes of human urine

A miniaturized sample preparation method is presented that is based on microextraction by packed sorbent (MEPS) to determine metabolites of monoterpenes in small volumes of human urine. A protocol including syringe modifications has been developed to exploit the concept of MEPS for application in gas chromatography-mass spectrometry with splitless injection. Only 210 mu L of enzymatically hydrolysed urine is needed to carry out a complete extraction protocol. Elution volumes between 1 and 10 mu L can be transferred completely or partly to the GC-MS system. All steps of filling and injection of the MEPS syringes are performed automatically. The utility of this approach was demonstrated in terms of determinations of the monoterpene metabolites cis-verbenol, trans-verbenol, alpha-terpineol, myrtenol and perillyl alcohol in a urine sample of a volunteer who lived in a dwelling with high indoor air exposure of monoterpenes.