Determination of chlormequat in fruit samples by liquid chromatography-electrospray-mass spectrometry/mass spectrometry.

An ion-pair liquid chromatography-mass spectrometry/mass spectrometry method was developed for the determination of chlormequat in fruit samples. A solid-phase extraction cleanup procedure with C18 cartridges was used. Sample preparation was simple and the achieved detection limit (0.03 mg/kg) and quantitation limit (0.08 mg/kg) were below the maximum residue levels legislated by the European Union. The chromatographic separation was performed by using a C8 column and heptafluorobutyric acid as ion pair reagent. The detection was conducted with an electrospray source and an ion trap as a mass analyzer. The reproducibility of the method gave good run-to-run (8-9%) and day-to-day (9-13%) precision values, and its applicability to the determination of chlormequat in pears and grapes, purées, and pear, apple, and grape juices was demonstrated.