Flow injection chemiluminescence determination of acetochlor and cartap-HCl in freshwater samples using an acidic KMnO4-rhodamine-B reaction system

A flow injection (FI) methodology using the acidic potassium permanganate (KMnO4)-rhodamine-B (Rh-B) reaction with chemiluminescence (CL) detection was established to determine acetochlor and cartap-HCl pesticides in freshwater samples. Experimental parameters were optimized, and Chelex-100 cationic exchanger mini column and solid-phase extraction (SPE) were used as phase separation techniques. Linear calibration curves were observed for the standard solutions of acetochlor and cartap-HCl over the ranges 0.005-2.0 mg L-1 [y = 1155.8x + 57.551, R-2 = 0.9999 (n = 8)] and 0.005-1.0 mg L-1 [y = 979.76x + 14.491, R-2 = 0.9998 (n = 8)] with LODs and LOQs of 7.5 x 10(-4) and 8.0 x 10(-4) mg L-1 (3 sigma blank) and 2.5 x 10(-3) and 2.7 x 10(-3) mg L-1 (10 sigma blank), respectively, with an injection throughput of 140 h(-1). These methods were used to estimate acetochlor and cartap-HCl with or without the SPE procedure, respectively, in spiked freshwater samples. Results obtained were not significantly different at a 95% confidence level to those of other reported methods. Recoveries for acetochlor and cartap-HCl were obtained over the ranges 93-112% (RSD = 1.9-3.6%) and 98-109% (RSD = 1.7-3.8%), respectively. The most probable CL reaction mechanism was explored.

Automated summary

A flow injection (FI) methodology using the acidic potassium permanganate (KMnO4)-rhodamine-B (Rh-B) reaction with chemiluminescence (CL) detection was developed for the determination of acetochlor and cartap-HCl pesticides in freshwater samples. The method showed good linearity and sensitivity, with LODs and LOQs as low as 7.5 x 10(-4) mg L-1 and 2.5 x 10(-3) mg L-1, respectively. The method was able to accurately estimate the concentrations of acetochlor and cartap-HCl in spiked freshwater samples, with recoveries ranging from 93% to 112% and 98% to 109%, respectively. The most probable CL reaction mechanism was also explored.