Analysis of carbofuran residues in soil by the stopped-flow technique

Abstract

A simple method for the determination of carbofuran by the stopped-flow technique and which is suitable for its routine analysis in soil samples is reported. The method was based on the coupling reaction between carbofuran phenol (the hydrolysis product of carbofuran) and diazotised sulphanilic acid to form a coloured compound, the rate of formation of which was monitored spectrophotometrically. The calibration graph was linear in the range 1–40 µg ml^–1(RSD, 2%) and the method was highly selective. The average recovery of carbofuran was 96.5% from soil, and <0.5 µg g^–1 could be detected. A procedure for the resolution of propoxur-carbofuran mixtures of mass ratios in the range 5 : 1–1 : 10 with a precision of ca. 3% is also described.