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Abstract
Two gas chromatography methods were developed for the determination of the acaricide bromopropylate in grapes. The first included chromatographic separation with a DB-1 column and electron capture detection (GC-ECD), while the second utilized chromatographic separation with a DB-5MS column and mass spectrometry detection (GC-MSD). Sample preparation was the same for both methods and included liquid–liquid extraction with dichloromethane and diethylether, centrifugation, and evaporation. The sample preparation and analysis steps were optimized. The evaluation of the methods by analysis of standard solutions of bromopropylate in hexane gave satisfactory results. The detection limits were 0.02 mg kg−1 for the GC-ECD method and 0.03 mg kg−1 for the CG-MS method, and the corresponding quantification limits were 0.04, and 0.06 mg kg−1, respectively. However, the analysis of spiked grape samples showed that the GC-ECD method could be problematic for the particular substrate. In the cases of very low concentrations of bromopropylate, elevated results were obtained, because of a co-eluting peak. This problem did not exist with the GC-MSD method, which revealed that the co-eluting peak results from the hydrolysis of bromopropylate and corresponds to one of its metabolites. In conclusion, the GC-MSD method proved to be the most reliable for the determination of bromopropylate in grapes, while the degradation of this pesticide in the particular substrate is a subject of interest for further scientific investigation.