Rapid analysis of multi-pesticide residues in lotus seeds by a modified QuEChERS-based extraction and GC–ECD

A modified quick, easy, cheap, efficient, rugged and safe method (QuEChERS) coupled to gas chromatography with electron capture detector (GC–ECD) was developed for rapid extraction and simultaneous determination of 36 pesticides in lotus seeds. The extraction solvent (acetone, ethyl acetate, acetonitrile, n-hexane and n-hexane in combination with ethyl acetate) and purifying agent (neutral alumina, primary secondary amine, graphite carbon block and florisil) for QuEChERS extraction were optimized. The GC–ECD method was in-house validated in terms of linearity, selectivity, reproducibility, stability and recovery. The limits of detection (LODs) of the developed GC–ECD method for all investigated pesticides ranged from 0.01 to 3.0 μg L−1 and limits of quantification (LOQs) from 0.05 to 10.0 μg L−1. The satisfactory data demonstrated the good reproducibility and stability of the method with relative standard deviations (RSDs) lower than 15%. Recoveries for spiked lotus seed samples were from 60.84% to 119.91% with RSDs lower than 13.06%. Two out of 24 batches of lotus seeds collected in China were found to be contaminated with trans-chlordane, which were below LOQ. This is the first attempt in China using QuEChERS to GC–ECD to determine 36 major pesticides with differences in physio-chemical properties in lotus seeds. The method described here was found to be practicable in the routine residue analysis of pesticides in lotus seeds.

► A modified QuEChERS method with GC–ECD was developed.
► The optimized QuEChERS method was satisfactory for simplicity and time-consumption.
► The validated GC–ECD method gave low LOD and satisfactory recoveries.
► The combinational method was applied for determining 36 pesticides in lotus seeds.