Development and validation of an analytical method for determining triflumezopyrim residues in multiple paddy field matrices (Paddy Water, Paddy Soil, Brown Rice, Rice Husk, and Rice Straw) using GC-ECD and GC-MS.

Triflumezopyrim (TFM), a neonicotinoid insecticide for rice planthopper control, poses potential risks to rice safety and paddy ecosystems via residues. Herein, gas chromatography-electron capture detector (GC-ECD) and GC-mass spectrometry (GC-MS, selected ion monitoring: m/z 206.0, 116.0, 131.0) methods were developed and validated for TFM residue analysis in paddy matrices. Samples were extracted with dichloromethane and purified by dispersive solid-phase extraction. For five matrices, calibration curves showed good linearity (0.01-1 mg L-1, R2 ≥ 0.9912). At 0.01, 0.1, 1 mg kg-1 spiking levels, mean recoveries were 81.04%-109.66% (GC-MS) and 89.45%-106.41% (GC-ECD), with relative standard deviations (RSDs) of 3.55%-13.08% and 0.59%-9.30%, respectively. Limits of quantitation (LOQ) were 0.01 mg kg-1 for both techniques; limits of detection (LOD) were 0.001 mg L-1 (GC-ECD) and 0.0005 mg L-1 (GC-MS). These parameters met current residue limits and analytical criteria. Robustness tests revealed minimal impacts of pretreatment and most chromatographic parameters, except carrier gas flow rate (critical, RSD > 10% when varied). The validated method was applied to real paddy field samples from Hunan Province, China, and 20 batches of five types of substrates were screened, with trace TFM in soil (below LOQ). This is the first validated GC-ECD/GC-MS method for TFM trace analysis covering the entire paddy ecosystem (paddy water, paddy soil, brown rice, rice husk, and rice straw), suitable for routine monitoring and supporting TFM environmental/food safety evaluation.