Analysis Of Pesticide Residues In Vegetables Research Articles

The application of in-source fragmentation in ultra-high performance liquid chromatography-electrospray ionization -tandem mass spectrometry for pesticide residue analysis

In this study, in-source fragmentation in ultra-high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UHPLC-ESI-MS/MS) was investigated and applied for pesticide residue analysis. Over 400 pesticides were tested, among which 26 pesticides were found to be sensitive to in-source fragmentation, producing 33 in-source fragments. The fragment pathways were studied and severe in-source fragmentation was observed due to the cleavage of C-O bond of carbamate, phosphate, ester, and ether groups, especially for isocarbophos and methoprene, leading to false negative results. High source temperatures could significantly increase the extent of in-source fragmentation. A multiple reaction monitoring (MRM) based multiresidue method was established for the pesticide residue analysis in vegetables and fruits, applying both pesticides and in-source fragments as precursors. The quantification ability of the method was validated and compared in terms of recovery, linearity, and the limit of quantification. In-source fragmentswere found to be more suitable than their parent pesticides as precursor ions for MRM analysis.

Quick, easy, cheap, effective, rugged and safe method with magnetic graphitized carbon black and primary secondary amine as adsorbent and its application in pesticide residue analysis

By using magnetic graphitized carbon black and primary secondary amine (GCB/PSA/MNPs) as adsorbent, a modified quick, easy, cheap, effective, rugged and safe (QuEChERS) method was proposed for pesticide residue analysis in vegetables. The magnetic adsorbent was fabricated via simple co-mixing method based on an “aggregate warp” mechanism. To achieve the optimum conditions of modified QuEChERS toward target analytes, several parameters, including the composition of analyte protectants and the amount of the adsorbents were investigated. Under the optimized conditions, a simple, rapid and effective method for the determination of 10 pesticide residues in vegetables was established by coupling modified QuEChERS to gas chromatography/mass spectrometry analysis. The detection limits of the proposed method for 10 pesticides ranged from 0.39 to 8.6ng/g. Good linearity (R value≥0.990) was achieved at concentration levels of 10–200ng/g, and acceptable method reproducibility was found as intra- and inter-day precisions, yielding the relative standard deviations less than 10.7% and 13.4%, respectively. The recoveries were in the range of 69.9–125.0% at different concentrations for real samples. Compared with the reported methods for the determination of a large number of samples, the proposed method has the advantage of less time-consuming in clean-up procedure.