T/CAIA SHO21-2024 Water quality Determination of alkyl mercury and inorganic divalent mercury by on-line solid-phase extraction-liquid chromatography-inductively coupled plasma mass spectrometry

Scope

Scope: This document specifies the method for determining alkyl mercury (methyl mercury, ethyl mercury) and inorganic divalent mercury in environmental water samples using online solid-phase extraction-liquid chromatography-inductively coupled plasma mass spectrometry. This document is applicable to the determination of alkyl mercury (methyl mercury, ethyl mercury) and inorganic divalent mercury in environmental water samples with a concentration range of 0.5 ng/L to 100 ng/L. The scope specified in this document has been validated through inter-laboratory trials. Laboratories can expand the measurement range by changing the sample volume. Once the measurement range has been expanded, the laboratory should confirm this with experimental methods. Main technical content: After filtration of the sample, the analysis and determination of mercury forms are carried out using an online solid-phase extraction-liquid chromatography-inductively coupled plasma mass spectrometry system. The sample is enriched and preliminarily separated and purified on the first-dimensional solid-phase extraction column, then switched by a six-way valve, and further separated and purified on the second-dimensional chromatography column. The purified components are directly introduced into the inductively coupled plasma mass spectrometer for the detection of mercury forms. Qualitative analysis is based on retention time, and quantitative analysis is performed using external standards. During the sample enrichment stage, a mercury-enrichment reagent is used to modify the SPE column. When the six-way valve is in the position shown in Figure 1a), the sample solution flows through the SPE column, and the mercury is retained on the SPE column by forming a complex with the enrichment reagent. During the sample elution and analysis stage, the position of the six-way valve is switched to the position shown in Figure 1b). At this time, the SPE column is connected in series with the C18 analytical column

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