FLOW-THROUGH SENSOR FOR THE DIRECT DETERMINATION OF PESTICIDE MIXTURES WITHOUT CHROMATOGRAPHIC-SEPARATION

A flow-through sensor for determination of carbamate compounds (carbofuran, propoxur, and carbaryl) based on retention of the products on C18 bonded phase beads packed in a flow-cell was developed. The associated determinative procedure relies on the hydrolysis of the analytes and coupling to diazotized sulfanilic acid to yield the corresponding dyes. A conventional flow injection (FI) method was also developed for comparison. A diode array spectrophotometer was used in both cases to monitor the reaction products at nine wavelengths, resulting in maximal differences between the absorption spectra. Linear calibration curves over the ng/mL to mu-g/mL range (determination limit 50 times lower than that of the conventional FI method) and excellent results on application to mixture resolution in water samples from different sources testify to the usefulness of the proposed sensor.