Improved sensitivity in detection of chlormequat by liquid chromatography-mass spectrometry

Two published separations, using electrospray mass spectrometry (ES-MS), ex hibit significant differences in Limits of detection (LODs) for chlormequat cation in pear. Separation on ODS1, confirmed to result from ion-exchange, gives shorter analysis times and calibration over a wider concentration ra nge than on an SCX cation-exchange column. The superior LOD using ODS1 (0.0 4 ng ml(-1) vs. 1.0 ng ml(-1)) results mainly from better chromatographic p eak shape. Separation on ODS1 combined with optimised ES-MS detection allow s direct quantification of chlormequat on an ion trap instrument at levels lower than those required for residue analysis in foods and also in drinkin g water. (C) 2000 Elsevier Science B.V. All rights reserved.