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, R2  = 0.9999 (n = 8)] and 0.005-1.0 mg L-1 [y = 979.76x + 14.491, R2  = 0.9998 (n = 8)] with LODs and LOQs of 7.5 × 10-4 and 8.0 × 10-4  mg L-1 (3σ blank) and 2.5 × 10-3 and 2.7 × 10-3  mg L-1 (10σ 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.