Flow injection chemiluminescent method for the analysis of Microbail-origin insecticides in aquatic system: a case study of spinosad and emamectin benzoate

Flow injection (FI) with chemiluminescence (CL) detection system applying tris-2,2/-bipyridylruthenium(II) – potassium permanganate ([Ru(bpy)3]2+–KMnO4) CL reaction was established to determine spinosad and emamectin benzoate Microbail-origin insecticides in freshwater samples. Experimental parameters were optimised, and solid phase extraction (SPE) was employed as phase separation techniques. Linearity of calibration plots for the standard solutions ranges of spinosad and emamectin benzoate were of 0.005–2.0 mg/L (R2 = 0.9997 (n = 8)) and 0.01–2.0 mg/L (R2 = 0.9994 (n = 7)), respectively. The respective Limit of Detections (LODs) and Limit of Quantifications (LOQs) for spinosad and emamectin benzoate were found as 1.3 × 10−3 and 3 × 10−3 mg/L [3σ blank, and 3.5 × 10−3 and 8.9 × 10−3 mg/L [10σ blank]. The injection throughput was 105 h−1. Because of applying tests of significance, the acquired results by the proposed method were not significantly different from those of reported methods at a 95% confidence level. Recoveries for spinosad and emamectin benzoate were achieved over the ranges of 94–107% (RSD = 1.8–3.6%) and 92–110% (RSD = 2.1–3.6%), respectively. The most possible CL reaction mechanism was investigated and formulated.