Identification of multi-insecticide residues using GC-NPD and the degradation kinetics of chlorpyrifos in sweet corn and soils

• The retention time of 12 pesticides determined by GC-NPD.
• The percent recoveries demonstrated that the analytical method is acceptable.
• Half-life of chlorpyrifos degradation in sweet corn and soil samples were assessed.
• The result were report the degradation of chlorpyrifos in sweet corn and soils.

Because more than one insecticide is applied to crops to protect plants from pests, an analytical multi-residue determination method was developed using gas chromatography with a nitrogen phosphorus detector (GC-NPD). The retention time for 12 insecticides was 3.7–27.7 min. Under the selected conditions, the limits of detection (LOD) and quantification (LOQ) were below the maximum residue limits (MRLs) and in the range of 0.00315–0.05 μg mL−1 and 0.01–0.165 μg mL−1, respectively. Using GC-NPD, we investigated the dissipation dynamics and final residual levels of chlorpyrifos in sweet corn and soil and determined that the half-lives was 4–7 days, that is, that chlorpyrifos is safe to use on sweet corn with a pre-harvest interval of 16–22 days before harvest. These results provide new insights into chlorpyrifos degradation in plants and its environmental behavior.