Optimization and evaluation of four multi-residue methods for the determination of pesticide residues in orange oil using LC-MS/MS and GC-MS/MS: a comparative study

Orange oil is considered the largest produced essential oils worldwide due to its unique properties. Pesticide residues in orange oil are expected to be much higher than the original fruit due to orange peel's cold-pressing during orange oil production. These residuesmaycause various health problems if consumed. The purpose of our study was to optimize and compare four multi-residues extraction methods (dilution, QuEChERS, ethyl acetate, and mini-Luke) for analysis of 387 pesticides in orange oil using LC-MS/MS and GC-MS/MS. To our knowledge, this is the first report on the use of ethyl acetate and the mini-Luke method for the analysis of orange oil. The comparison was based on recoveries, matrix effect, and the amount of co-extract matrix. The optimum mean recoveries were obtained by the ethyl acetate method, which successfully analyzes 371 out of 387 pesticides with acceptable recovery (70-120%). It also showed a narrow recovery distribution in the range of 90-110% for 69% of all studied pesticides. Regarding the matrix effect, the QuEChERS method gave the highest number of pesticides with an in significant matrix effect (80-120%) for both LC and GC amenable pesticides. The least amount of co-extract matrix components according to GC-MS/MS scan and gravimetric analysis has been achieved by the QuEChERS method. In conclusion, the Ethyl acetate method gives acceptable recovery for a wide range of pesticides with a narrow recovery distribution and a moderate amount of co-extract matrix. While the QuEChERS method provides better selectivity and cleaner extract but with a narrow scope and less precision.