Potassium Bromate–quinine Chemiluminescence Detection of Thiram in Water Samples using Flow Injection Analysis

Resumo

A flow injection-chemiluminescence (FI-CL) method is devised for the determination of thiram in natural water samples. The CL intensity is enhanced when thiram is oxidized with potassium bromate under strong acidic conditions subsequently using quinine as a sensitizer. Under the optimum experimental conditions the relative CL intensity was proportional to the concentration of thiram in the range from 0.001 to 20 mg/L with the limit of detection (S/N = 3) 6 × 10^–4 mg/L and the throughput of injections of 200 samples/h. The coefficient of determination (R²), relative standard deviation (n = 4) and regression equation over the studied range were 0.9998 (n = 11), 0.94–1.76% and y = 873.9x – 41.1 (y corresponds to the CL intensity, mV, and x is the concentration of thiram, mg/L), respectively. The proposed method was applied for the determination of thiram in spiked natural water samples and results obtained were in good agreement with the previously reported HPLC method. A brief discussion on the possible CL reaction mechanism between thiram and potassium bromate enhanced by quinine has been described.