Simultaneous determination of sixteen amide fungicides in vegetables and fruits by dispersive solid phase extraction and liquid chromatography-tandem mass spectrometry

A modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method using multi-walled carbon nanotubes (MWCNTs) as a reversed-dispersive solid phase extraction (r-dSPE) material combined with ultra-high liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) was developed for the simultaneous determination of 16 novel amide fungicides in vegetables and fruits. After extraction with acetonitrile, a dSPE cleanup procedure, which was developed after the optimization of the type and amount of MWCNTs, the pH value of the extract, the extraction time for MWCNTs, and the type of eluent with MWCNTs material, was conducted. The determination of the target compounds was conducted in less than 7.0 min while the specificity is ensured through the MRM acquisition mode. The linearity of the analytical response across the studied range of concentrations (0.25-500 mu g/L) was excellent, obtaining correlation coefficients higher than 0.997. The samples were quantified with the matrix matched standard solutions. The average recoveries in cabbage, celery, strawberry, and grape at three spiked levels (0.01, 0.5, and 5.0 mg/kg) were ranged from 72.4 to 98.5% with all RSDs lower than 10%. The limits of detection were below 0.003 mg/kg and the limits of quantification did not exceed 0.01 mg/kg in all matrices. The method demonstrated to be suitable for the simultaneous determination of 16 novel amide fungicides in vegetables and fruits. (C) 2015 Elsevier B.V. All rights reserved.