ISO DIS 22104
Water quality — Determination of microcystins — Method using liquid chromatography and tandem mass spectrometry (LC-MS/MS)
|Publication Date:||1 July 2020|
|ICS Code (Examination of water for chemical substances):||13.060.50|
Although ISO 20179 for microcystin analysis by HPLC UV has been elaborated, the UV detection nevertheless requires several steps of sample clean-up and concentration to achieve detection limits in the range of micrograms per litre, μg/l. A more sensitive and effective method for quantitative determination of microcystins is been required.
This document specifies a method for the quantitation of twelve microcystin variants (microcystin-LR, -LA, -YR, -RR, -LY, -WR, -HtyR, -HilR, -LW, -LF, [Dha7]-microcystin-LR, and [Dha7]-microcystin-RR) in drinking water and freshwater samples. The method can be used to determine further microcystins, provided that analytical conditions for chromatography and mass spectrometric detection has been tested and validated for each microcystin. Samples are analysed by LC-MS/MS using internal standardization.
This method is performance based. The analyst is permitted to modify the method, e.g. increasing direct flow injection volume for low interference samples or diluting the samples to increase the upper working range limit, provided that all performance criteria in this method are met.
Detection of microcystins by high resolution mass spectrometry (HRMS) as an alternative for tandem mass spectrometry (MS/MS) is described in Annex A.
An alternative automated sample preparation method based on on-line solid phase extraction coupled to liquid chromatography is described in Annex B.
When instrumental sensitivity is not enough to reach the method detection limits by direct flow injection, a solid phase extraction clean-up and concentration step is described in Annex C.