AbstractA recent publication concerning the analysis of residues of the herbicide chlormequat in cotton seed by gas chromatography contains a significant error. A derivative prepared by reacting pentafluorothiophenol with chlormequat is actually produced by the reaction of the initial product of demethylation of chlormequat with a second molecule of pentafluorothiophenol. As the derivative is not derived from the chlormequat backbone, the method is not specific to chlormequat and could be misleading to an analyst using it or adapting it to other produce.