SPECTROPHOTOMETRIC DETERMINATION OF CARBAMATE PESTICIDES WITH DIAZOTIZED TRIMETHYLANILINE IN A MICELLAR MEDIUM OF SODIUM DODECYL-SULFATE

The spectrophotometric determination of the carbamate pesticides carba ryl, bendiocarb, carbofuran, methiocarb, promecarb and propoxur is pro posed, The pesticides are hydrolyzed in alkaline medium to 1-naphthol or phenolates, which are coupled with diazotized trimethylaniline (TMA ) in a sodium dodecyl sulfate micellar medium to form the azo dyes, Th e micellar medium increased the solubility of TMA and enhanced the sen sitivity, The performance of TMA was compared with that of sulfanilic acid, which is the conventional reagent used in these determinations, Although the absorbance of the azo dyes of sulfanilic acid was also en hanced in the micellar solution, the sensitivity was still greater wit h TMA, Further, at the pH required for the coupling reaction (9.5), th e absorbance of the blank was negligible with TMA but large with sulfa nilic acid. Using TMA, the limits of detection were in the range 0.2-2 mu g cm(-3). The procedure was applied to the determination of carbar yl in spiked tap, river and pond water samples and to the evaluation o f various carbamates in commercial pesticide formulations.