Optimisation and application of the multi-residue analysis method for detection of 50 pesticides in cabbage by using LC-MS/MS- QuEChERS

A multi-residue method for simultaneous determination of 50 pesticides in cabbage, belonging to different chemical classes has been developed by LC-MS/MS. The pesticides were analysed simultaneously in a single run using positive electrospray ionisation with multiple reaction monitoring (MRM) after extraction with modified QuEChERS method. The calibration curve for each analyte was linear with the concentration of 0.0025, 0.005 0.01, 0.025, 0.05 and 0.10 µg mL−1 with a correlation coefficient which ranged between 0.993 and 0.999. The mean recoveries obtained for four fortification levels (0.01, 0.025, 0.050 and 0.10 μg/g) were 77.96–119.67% with satisfactory precision (RSD < 20%). The matrix effects were found in range of 6.42 to 19.52% with optimised cleanup process. The developed method was used to investigate the occurrence of pesticides residue in cabbage head samples collected from different markets of the Varanasi region, India. All the 50 compounds were eluted from the column of the LC-MS/MS within the 7.961 min. The limit of quantification of the optimised method was 0.01 mg kg−1 for all the 50 pesticides. Therefore, it would be recommended as a very sensitive and quick method for estimation of multi-residue in cabbage. The developed method was successfully utilised for the analysis of the market samples collected from four different market of the Varanasi, India. Total five compounds namely thiamethoxam, carbendazim, imidacloprid, acetamiprid and dimethoate were detected in cabbage samples. Out of five compounds, only two compounds i.e. acetamiprid and dimethoate are recommended by Central Insecticide Board and Registration Committee (CIB&RC), Govt. of India.