A multiresidue method for simultaneous determination of 44 organophosphorous pesticides in Pogostemon cablin and related products using modified QuEChERS sample preparation procedure and GC-FPD.

In this study, a modified quick, easy, cheap, efficient, rugged and safe (QuEChERS) method coupled with gas chromatography with flame photometric detection (GC-FPD) was developed for the determination of 44 organophosphorous pesticide (OPP) residues in 44 batches of Pogostemon cablin and its related products for the first time. The QuEChERS extraction conditions were optimized, and the matrix effect that may influence recoveries was evaluated and minimized by matrix-matched calibration curves. Under the optimized conditions, the calibration curves for all OPPs showed good linearities in the concentration range of 0.04-1.5 μg mL(-1) with correlation coefficients better than 0.9909. The limits of detection were in the range of 0.004-0.02 μg mL(-1) and quantification were 0.01-0.04 μg mL(-1), below the regulatory maximum residue limits suggested. Mean recoveries ranged between 76.62 and 113.7% (99.34% on average), and relative standard deviation was 3.71% on average. The validated method was applied on 44 real samples including P. cablin, and P. cablin oil and powder. Two (4.5%) samples were found to be contaminated by chlorpyrifos with levels below the legal limits, which were successfully confirmed by gas chromatography-mass spectrometry (GC-MS). Based on the results, the developed method was proved to be simple, fast, accurate, low cost and environmentally friendly and can be successfully applied in the determination of targeted OPP residues in P. cablin and its related products. Moreover, it also attaches great importance to pesticide monitoring programs in food, soil and air in the future.