Abstract: A confirmatory method is proposed for the determination of 12 azole fungicide residues in beans and corn with the technique of offline disperse solid phase extraction (DSPE) and gas chromatography-negative chemical ionization mass spectrometry (GC-NCI/MS). The pesticides interested were extracted from the samples with acetonitrile containing 1% acetic acid and simultaneous liquid-liquid partitioning formed by adding anhydrous magnesium sulfate plus sodium acetate followed by a simple cleanup step known as dispersive solid-phase extraction. The aliquot was determined and confirmed by GC-NCI/MS using external standard method. The recoveries of all pesticides were between 70% and 130% at the three spiked levels, 10 μg/kg, 20 μg/kg and 40 μg/kg. The relative standard deviations were less than 13.9%. The linearity of method was good from 50 to 1000 μg/L. The limits of quantification (LOQ) were less than 8 μg/kg. The method is selective with no interference and is suitable for the confirmatory of pesticide residues in beans and corn.

Key words: azole fungicides, beans, corn , disperse solid phase extraction, selected ion monitoring, gas chromatography-negative chemical ionization mass spectrometry (GC-NCI/MS)