Analytical Sciences

Determination of Thiram and Aminocarb Pesticides in Natural Water Samples Using Flow Injection with Tris(2,2′-bipyridyl)ruthenium(II)-diperiodatoargentate(III) Chemiluminescence Detection

Mohammad ASGHAR,* Mohammad YAQOOB,* Naheed HAQUE,** and Abdul NABI*

*Department of Chemistry, University of Balochistan, Sariab Road, Quetta 87300, Pakistan
**Department of Pharmacy, University of Balochistan, Sariab Road, Quetta 87300, Pakistan

A simple and sensitive flow-injection (FI) method is reported for the determination of thiram and aminocarb pesticides in natural water samples based on the strong enhancing effects of these pesticides on the tris(2,2′-bipyridyl)ruthenium(II)-diperiodatoargentate(III) (Ru(bipy)₃²⁺-DPA) chemiluminescence (CL) system. Under the optimum experimental conditions, the CL intensity was linear over the range of 1.0 – 1000 and 1.0 – 10000 ng mL⁻¹ (R² = 0.9998 (n = 7) and 0.9994 (n = 11)) for thiram and aminocarb, respectively, with relative standard deviations (RSDs; n = 3) in the range 1.0 – 2.6%. The limits of detection (S/N = 3) were 0.1 ng mL⁻¹ for both pesticides with injection throughputs of 150 h⁻¹. The key chemical and physical variables (reagent concentrations, flow rates, sample volume, PMT voltage) were optimized and potential interferences investigated. The method was successfully applied to natural water samples and the results obtained were not significantly different (95% confidence interval) from results obtained by the previously reported FI–CL and HPLC methods. Thiram could be determined in the presence of aminocarb using Triton X-100. The possible CL reaction mechanism is also discussed briefly.

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