Determination of Chlormequat in Pears by Liquid Chromatography/Mass Spectrometry

A straightforward and reliable method was developed for the determination of chlormequat in pears by liquid chromatography/mass spectrometry (LC/MS). Water and methanol were compared as extraction solvents. Because no significant differences in extraction efficiency or repeatability were found, water was chosen as the extraction solvent. The extracts were analyzed without cleanup by either an ion-trap liquid chromatograph/mass spectrometer in the single MS mode or a triple-quadrupole instrument in the MS/MS mode, using electrospray ionization. Both instruments were equally suitable for quantitation and confirmation of identity. Recoveries were 76–103%, and reproducibility was ≤12%. The lowest detection limit (0.007 mg/kg) was obtained with the triple-quadrupole instrument in the MS/MS mode.