Determination of RH-5849 and indoxacarb in rice straw, rice husk, brown rice and soil using liquid chromatography-tandem triple quadrupole mass spectrometry following extraction with QuEChERS method.

A fast and simple analytical method was developed for the simultaneous determination of RH-5849 and indoxacarb in soil, rice straw, rice husk and brown rice. QuEChERS (quick, easy, cheap, effective, rugged and safe) method was used for extraction, and liquid chromatography with tandem triple quadrupole mass spectrometry was used for quantification. The matrix-matched calibration plots were linear in the range between 25 and 5000 μg/L for soil, rice straw, rice husk and brown rice samples. All determination coefficients (R(2) ) were ≥0.9962. The limits of detection and quantification were 1.5 and 5 μg/kg, respectively. Recoveries at three fortification levels ranged between 79.5 and 97.9% with relative standard deviations <11%. The developed method was validated and applied for the analysis of dissipation study samples. For field experiments, the half-lives of RH-5849 and indoxacarb in rice straw were 11.93 and 5.83 days, respectively. The method was demonstrated to be reliable for the routine monitoring of RH-5849 and indoxacarb in rice samples.