A simple chromatographic method is proposed to analyse N-methylcarbamate insecticides by post-column derivatization and fluorescence detection. The new method performs the post-column reaction without the necessity of using any delivery pumps to introduce the reagents after the analytical column in the chromatographic system. The simplification is possible since the hydrolysis (at basic pH) and derivatization (with o-phthaldialdehyde and 2-mercaptoethanol) reagents are present in the mobile phase. Analytical columns (which tolerate basic conditions) and pH of the mobile phase were studied. Kromasil-100-C18 column and berate buffer were chosen. The length and the temperature of the tubular reactor were also optimised. Results of the validation study with the proposed chromatographic method are shown. The values demonstrated good performance of the complete system, including the post-column derivatization reaction. The column showed constant efficacy for more than 200 injections.