Mass spectrometric screening method for microcystins in cyanobacteria.
A screening method for microcystins in cyanobacteria, which consists of the formation of 3-methoxy-2-methyl-4-phenylbutyric acid as an oxidation product of microcystins by ozonolysis, and detection of 3-methoxy-2-methyl-4-phenylbutyric acid by thermospray-liquid chromatography/mass spectrometry or electron ionization-gas chromatography/mass spectrometry using selected ion monitoring, was developed. The ozonolysis made it possible to significantly reduce the formation times of 3-methoxy-2-methyl-4-phenylbutyric acid because the previously required extraction, clean-up and other procedures could be entirely eliminated. The resulting intact 2-methyl-4-phenylbutyric acid was directly analyzed by thermospray-liquid or electron ionization-gas chromatography/mass spectrometry, and the procedures from ozonolysis to analysis of microcystins at the pmole levels were performed within only 30 min. The calibration curves obtained by thermospray-liquid or electron ionization-gas chromatography/mass spectrometry analysis showed a linear relationship from 14 to 830 pmole and from 2.5 to 100 pmole of microcystin-LR, respectively. The method was applied to the detection and determination of the total amount of microcystins in bloom and cultured samples, showing that it provided a means of not only screening for microcystins but of their accurate quantitation.
Harada
K
K
Faculty of Pharmacy, Meijo University, Nagoya, Japan.
Murata
H
H
Qiang
Z
Z
Suzuki
M
M
Kondo
F
F
D002138:Calibration; D002273:Carcinogens / Q000032:analysis / Q000378:metabolism*; D000458:Cyanobacteria / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000032:analysis / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D052998:Microcystins; D010126:Ozone / Q000737:chemistry; D010456:Peptides, Cyclic / Q000032:analysis / Q000378:metabolism*; D010654:Phenylbutyrates / Q000032:analysis / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors*
C105366:3-methoxy-2-methyl-4-phenylbutyric acid; D002273:Carcinogens; D004791:Enzyme Inhibitors; D052998:Microcystins; D010456:Peptides, Cyclic; D010654:Phenylbutyrates; D010126:Ozone; C078588:microcystin; C075773:4-phenylbutyric acid; D010749:Phosphoprotein Phosphatases