Development, optimization and validation of QuEChERS based liquid chromatography tandem mass spectrometry method for determination of multimycotoxin in vegetable oil

Abstract

In recent years, vegetable oils have been reported to be contaminated by mycotoxins. A new method was developed, optimized and validated for the simultaneous determination of aflatoxins (AFs), ochratoxin A (OTA), deoxynivalenol (DON) and zearalenone (ZEA) in vegetable oil by a modified Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) technique. A quick procedure of mycotoxins extraction and clean-up was achieved in two steps. Firstly, target analytes were extracted into the optimized solvent acetonitrile and followed by dispersive solid phase extraction (d-SPE) sorbent clean up with the optimized sorbents to remove the co-extracts. Three types of d-SPE sorbents; C18; Primary Secondary Amine (PSA); Graphitized Carbon Black (GCB) and four combination ratios of two selected d-SPE sorbent were evaluated to achieve an optimum and acceptable result. The maximum co-extracts were removed when C18 and GCB were used at ratio 3:1 with MgSO4 anhydrous followed by liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis. The validation study showed all analytes could be detected between 0.01 and 650.17 ng g−1 concentration ranges with correlation coefficient >0.98. The limit of quantitation ranges from 0.04 to 2000 ng g−1. The recoveries were in a range of 87.9–106.6%. The repeatability and reproducibility of the analysis were between the ranges of 0.5–1.3, within the acceptable level for precision. Significant matrix effect was compensated using the matrix matched calibration curves. The method was successfully applied to 25 vegetable oil samples including corn oil, palm oil and sunflower oil. ZEA, AFG2, AFG1 and AFB1 were among the detected analytes.