Cyanotoxin analysis: greater sensitivity and a comprehensive view

Phytocontrol laboratory offers cyanotoxin analysis by LC-MS/MS, a reference technique for detecting microcystins in freshwater.

Our R&D department has just taken a new step forward with two major developments to this method, enabling it to respond even more precisely to regulatory requirements and field needs.

Following the amendment to the regulation, we have lowered the limit of quantification to 0.1 µg/L for extracellular microcystins (dissolved form). This development of our method strengthens its reliability, robustness and reproducibility, and ensures full compliance with current regulations, in particular the DGS recommendations, which set an alert threshold of 0.3 µg/L for microcystins in bathing water.

Initially limited to extracellular analysis, our method can now also analyse the intracellular fraction. This development provides a measurement of total cyanotoxins, giving a more complete picture of a sample’s contamination.

For treated freshwater, our COFRAC-accredited cyanotoxin analysis method reports results in the extracellular fraction only.

However, for untreated freshwater, results can be expressed either as the extracellular (dissolved) fraction or as total cyanotoxins (including both extracellular and intracellular fractions).

What is the regulatory context?

Cyanotoxin analysis falls within a clear regulatory framework, particularly for bathing water, under instruction DGS/EA4/EA3/2021/76:

Where chlorophyll a > 10 µg/L is present, identification of cyanobacteria is required.

If potentially toxin-producing genera are present, a biovolume count is carried out (results are expressed as biovolumes):

• No alert if the sum of cyanobacteria biovolumes ≤ 1 mm3/L

• Level 1 alert if the sum of cyanobacteria biovolumes > 1 mm3/L and no toxin thresholds are exceeded: toxins are tested for and normal activity is maintained on site. The public is informed.

• Level 2 alert if the sum of cyanobacteria biovolumes > 1 mm3/L and one of the following toxin thresholds is exceeded:

• Microcystin > 0.3 µg/L

• Saxitoxin > 30 µg/L

• Cylindrospermopsin > 42 µg/L

• Anatoxin > LOD

In the event of an alert: swimming is banned, the public is informed, water sports are restricted, and eating fish is not recommended.

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