Determination of thiols by gas purge microsyringe extraction coupled with chemical derivatization by high performance liquid chromatography-fluorescence detection with mass spectrometry identification

A new fluorescence labeling reagent 1-(4-(1 H-phenanthro[9,10-d]imidazol-2-yl)phenyl)-1 H-pyrrole-5-dione (PIPD) used for the sensitive determination of thiols in food samples has been successfully prepared. Thiols were extracted by a gas purge microsyringe extraction (GP-MSE) device. The derivatization of PIPD with thiols could be finished within 10 minutes at 35 °C in weak alkaline condition, and the corresponding derivatives showed excellent fluorescence properties with excitation and emission wavelengths of 264 nm and 396 nm, respectively. The eight thiol derivatives could be easily separated on normal reversed phase column because of the introduction of highly hydrophobic PIPD unit into the target analytes. It is the first time that GP-MSE has been applied to the extraction of a wide range of thiols in food samples with only a small amount of methanol (0.5 mL) needed. The limits of detection (LODs) were in the range of 0.19–0.98 µg/kg, while the recoveries were in the range of 85.6%–97.1% with relative standard deviations (RSDs) < 4.98%. Good linearities were observed for all analytes with correlation coefficients of higher than >0.9995.GRAPHICAL