title: Quantitative analysis of cyanobacterial toxins by matrix-assisted laser desorption ionization mass spectrometry.
abstract: Microcystins (MCs) are a growing problem in drinking water supplies worldwide. Common analytical techniques used to determine MC concentrations have several shortcomings, including extensive sample handling and lengthy analysis times. A simple, rapid method for quantitation of MCs by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is presented. Four potential internal standards were tested, including an 15N-labeled MC. For MC-LR in mixed standard solutions, a linear range of 0.11-5.0 microM (R2 = 0.98) was achieved, with a method detection limit (MDL) of 0.015 microM. Matrix effects due to extracted cell components decreased the MC-LR linear range slightly to 0.19-5.0 microM (R2 = 0.99), with MDL = 0.058 microM. Extensive analysis of possible internal standards indicates that nodularin was preferred over [15N]10-microcystin-YR or angiotensin I. The ionization efficiency and analyte-analyte suppression for four MCs of varying polarity are presented; the three polar congeners exhibited good ionization efficiency and acceptable levels of analyte-analyte suppression. These results indicate that MALDI-TOF MS represents a viable alternative for the quantitative measurement of MCs in field samples.
authors.affiliation: Department of Chemistry, State University of New York, College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, New York 13210, USA.
authors.forename: Karen L
authors.initials: KL
authors.lastname: Howard
authors.forename: Gregory L
authors.initials: GL
authors.lastname: Boyer
mesh_terms: D000803:Angiotensin I / Q000032:analysis; D001427:Bacterial Toxins / Q000032:analysis*; D000087522:Cyanobacteria Toxins; D008387:Marine Toxins / Q000032:analysis*; D052998:Microcystins / Q000032:analysis*; D009587:Nitrogen Isotopes; D010456:Peptides, Cyclic / Q000032:analysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D014871:Water Microbiology; D014881:Water Supply / Q000032:analysis*
chemical_list: D001427:Bacterial Toxins; D000087522:Cyanobacteria Toxins; D008387:Marine Toxins; D052998:Microcystins; D009587:Nitrogen Isotopes; D010456:Peptides, Cyclic; C063998:nodularin; C065685:microcystin YR; D000803:Angiotensin I