[Determination of 12 azole fungicide residues in beans and corn by offline disperse solid phase extraction and gas chromatography-negative chemical ionization mass spectrometry].

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 microg/kg, 20 microg/kg and 40 microg/kg. The relative standard deviations were less than 13.9%. The linearity of method was good from 50 to 1 000 microg/L. The limits of quantification (LOQ) were less than 8 microg/kg. The method is selective with no interference and is suitable for the confirmatory of pesticide residues in beans and corn.