High-performance liquid chromatography equipped with post-column fluorescence derivatization provides an automated and specific analytical method for pesticide determination. Carbosulfan, a carbamate pesticide, can be analysed utilizing an existing and proven carbamate system after the addition of one additional hydrolytic reactor in-line. Extraction of this compound from citris crops requires careful handling owing to the volatility and unstable nature of the analyte in acid conditions. This paper describes the necessary instrument modifications and presents a method for carbosulfan extraction. Analyses of orange homogenates were performed rapidly with recoveries of between 66 and 98% for residue levels between 0.03 and 0.25 micrograms kg-1.