Determination of low levels of poly(ethylene glycol) 400 in plasma and urine by capillary gas chromatography-selected ion-monitoring mass spectrometry after solid-phase extraction.

A convenient and sensitive method for the quantitative determination of poly(ethylene glycol) 400 in plasma and urine with capillary gas chromatography-mass spectrometry has been developed. The sample preparation involves solid-phase extraction with subsequent derivatization with heptafluorobutyric anhydride, which proved to give the most stable derivative. The derivatization procedure was optimized using experimental design, and different solid-phase extraction columns were evaluated. The limit of quantitation was 1 micromol/l (0.4 microg/ml) for both plasma and urine.