title: An enhanced LC-MS/MS method for microcystin-LR in lake water.
abstract: A LC-MS/MS method with enhanced sensitivity and specificity was established for monitoring microcystin-LR (MC-LR) in drinking water supplies in southern Taiwan. The enhanced sensitivity was achieved by the selection of a doubly charged MC-LR as the precursor ion to result in an multiple reaction monitoring (MRM) pair ions of m/z 498.6 --> 135.0. Using this ion pair, a record low detection limit of 2 pg was achieved on column, found in the available literature. A sample preparation method involving C8 solid-phase extraction gave satisfactory recoveries of the analyte. Nodularin, with structural similarity to MC-LR, was used as an internal standard to minimize matrix effects of water samples collected from six different water reservoirs in southern Taiwan, where MC-LR was detected at sub-ppb levels in all the reservoirs. The best precision and accuracy of this method were found with samples prepared to contain MC-LR at 0.1 and 1 microg l(-1). This new method requires considerably smaller water sample volumes because of enhanced quantification sensitivity and hence reduces the time needed for analysis. It should serve as a useful example for method development for monitoring other members of the microcystin family in drinking water supplies.
authors.affiliation: Division of Environmental Health and Occupational Medicine, National Health Research Institutes, Kaohsiung, Taiwan.
authors.forename: Chien-Ming
authors.initials: CM
authors.lastname: Li
authors.forename: Ricky Yuan-Yuan
authors.initials: RY
authors.lastname: Chu
authors.forename: Dennis Paul
authors.initials: DP
authors.lastname: Hsientang Hsieh
mesh_terms: D002138:Calibration; D002853:Chromatography, Liquid / Q000379:methods*; D005618:Fresh Water / Q000737:chemistry* / Q000382:microbiology*; D013058:Mass Spectrometry / Q000379:methods*; D052998:Microcystins; D015394:Molecular Structure; D010456:Peptides, Cyclic / Q000032:analysis* / Q000737:chemistry; D012680:Sensitivity and Specificity; D013624:Taiwan; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D052998:Microcystins; D010456:Peptides, Cyclic; D014874:Water Pollutants, Chemical; C078588:microcystin