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

Two published separations, using electrospray mass spectrometry (ES-MS), exhibit 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 range than on an SCX cation-exchange column. The superior LOD using ODS1 (0.04 ng ml(-1) vs. 1.0 ng ml(-1)) results mainly from better chromatographic peak shape. Separation on ODS1 combined with optimised ES-MS detection allows direct quantification of chlormequat on an ion trap instrument at levels lower than those required for residue analysis in foods and also in drinking water. (C) 2000 Elsevier Science B.V. All rights reserved.