Determination of chlormequat residues in pears and pear concentrates by benchtop LC-ESI-MS

Abstract

SummaryA fast, simple and robust method for the routine determination of chlormequat (CCC) in pears and pear concentrates is described. The method is based on sample clean-up using an SPE strong cationic exchange (SCX) cartridge followed by analysis on a benchtop liquid chromatograph coupled to an atmospheric pressure electrospray ionisation mass spectrometer (LC-ESI-MS). The instrument is equipped with a weak cationic exchange (WCX) column. For quantification, ions m/z 122 and 124, representing the chloro isotopes of the molecular ion, are monitored. Recoveries for chlormequat at three levels (50, 100, 250ppb) from pears are in the range of 81-85 %, and from pear concentrates in the range of 90-93 %. The dynamic range covers concentrations from 10 to 500 #g kg -1 (ppb) with a correlation coefficient ofr = 0.999. During validation, the reproducibility (RSD) for the standard solution is found to be 4.3 % (n=8; within one day) and 6.0% (n= 16, day-to-day), the limit of detection (LOD) is 3 ppb (3 S/N) and the limit of quantitation (LOQ) is 10 ppb. Residue levels in pears purchased from a local supermarket in December 1998 and January 1999 were as high as 8 mgkg -1 (8 ppm). The method can also be applied to the determination of CCC in other fruits and concentrates e.g. apples and grapes.

An improved method for analyzing chlormequat and mepiquat in source waters by solid-phase extraction and liquid chromatography–mass spectrometry

“…In order to solve the problem of ESI-MS ion suppression during sample analysis, Miyun Reservoir source water samples were analyzed using SPE pre-concentration to establish matrix-matched standard calibrations for the quantification of CQ and MQ in source water samples. The matrix-matched calibration curves were established in the 0.1-5 g L −1 range because the actual levels of the plant growth regulators are usually very low [2,5]. The linear regression data are summarized in Table 2.…”

“…Chlormequat (CQ) and mepiquat (MQ), the two quaternary ammonium compounds, are widely applied as the plant growth regulators to promote flower formation, improve fruit setting in fruits and vegetables and reduce vegetative growth and the inhibition of sprouting [2,5,6]. CQ also elicits adverse effects on animal reproduction and has been classified as a suspected endocrine disruptor in the database of toxic chemical substances (RTECS) by the National Institute for Occupational Safety and Health (NIOSH) [7].…”

Uncertainty Analysis of Chlormequat Residue in Fruits by LC–MS–MS

“…These methods suffer from some drawbacks that cause false positives, especially at low residual levels. Recently, some papers have reported analysis of CCC residues in fruit and grain samples using the LC-MS-MS method [4][5][6][7][8][9]. These methods describe reversed-phase LC or ion-exchange LC coupled to MS-MS for determination of CCC.…”

Chlormequat Selective Electrodes: Construction, Evaluation and Application at Fia Systems

“…Due to the overall complexity of the relevant sample matrices, as well as the low concentrations expected in contaminated samples, almost all methods require a detection system capable of producing both quantitative and qualitative information. For this reason mass spectrometry is nearly the only detec-tion system proposed in the literature, and may be associated with liquid chromatogra-phy [3][4][5][6][7][8][9][10][11][12][13], thin layer chromatography [14] and electrophoresis systems [15,16]. Independently of the separation approach, the use of mass spectrometry is connected to high capital investment, which makes it unsuitable for routine applications.…”