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Algal Toxins

Cyanobacteria, known also as blue green algae, are found in freshwater lakes, reservoirs, rivers, and marine waters. They are of the most concern to many health and water authorities. This is because several species of cyanobacteria can produce potent toxins, which have caused numerous wildlife and domestic animal deaths in many countries.The AWQC has an excellent record in algal toxin analysis and research. It provides a rapid service for the quantitative determination of toxins produced by algal blooms and has assisted the water industry in this area throughout Australia and also overseas.

Toxin analyses

Many techniques are available for determining cyanotoxins, e.g. enzyme linked immunosorbent assay (ELISA), protein phosphatase inhibition assay, capillary electrophoresis (CE), and high performance liquid chromatograph (HPLC) coupled with various detection techniques such as photo diode array (PDA), fluorescence and mass spectrometry.

Of all the techniques, HPLC instrumental analysis is the most reliable and accurate. At AWQC, the OCHEM Laboratory has developed many HPLC methods and provides a comprehensive analytical service for a wide range of toxins, including microcystins, nodularins, anatoxin-a, cylindrospermopsins and saxitoxins. We also evaluate other assays such as ELISA kit and protein phosphatase inhibition assay, and compare them with HPLC methods.

All our HPLC methods are designed to analyse both extracellular toxins (dissolved toxins) and intracellular toxins (toxins inside cyanobacterial cells). All methods are fully validated and many of them are NATA accredited.

HEPATATOXINS — Microcystins and Nodularins

Microcystins are cyclic peptides produced mostly by Microcystis aeruginosa and several other species. There are over 70 structural variants but approximately 20 are most frequently detected in freshwater lakes, reservoirs, rivers and marine water. Nodurlarin, a similar cyclic peptide, is produced by Nodularia spumigena.

Microcystins and nodularin can be determined, simultaneously, by HPLC/DAD. With a sample pre-concentration step, our NATA accredited method can report microcystin-RR, -YR and –LR at the level of 0.1 μg /L, which is well below that in the Australian Drinking Water Guideline. The reporting limit for nodularin is also 0.1 μg /L. Intracellular and extracellular toxin are reported separately, and the total m-LR equivalent is calculated to comply with proposed guidelines.

We also have a NATA accredited method to analyse microcystins and nodularins in scum samples.

NEUROTOXINS — anatoxin-a and saxitoxins

Anatoxin-a, is neurotoxic alkaloid. Our fully validated HPLC/MS/MS method produces the most reliable and accurate results with a fast turn-around time and an absolute confirmation. The reporting limit is 0.1 μg/L.

Saxitoxin known also as Paralytical Shellfish Poison (PSP),is a neurotoxin naturally produced by certain species of marine dinoflagellates and cyanobacteria.

The PSP neurototoxins consist of 18 compounds with vastly different toxicities and structures and are most difficult to analyse. Several techniques can be used for their determination. However, there is not a method that gives the reliable and accurate results, within the required reporting limits for surface water and drinking water, while, at the same time, gives a fast turn-around time.

The analytical method employed at the OCHEM laboratory is the HPLC/post-column derivertisation fluorescence detection technique. It requires three chromatographic runs and a high level of expertise in instrument operation and result interpretation. However, it is the only analytical method that can produce a complete separation and determination of saxitoxins at the required reporting limits. This validated method can report the individual toxins at 0.5 μg/L for both intracellular and extracellular toxins. STX equivalent also is calculated for determining the compliance with proposed guidelines.

Non-specific toxin — Cylindrospermopsin can be determined by HPLC/MS/MS method. Our fully validated method provides reliable and accurate results with a fast turn-around time and at the required reporting limit, 0.1 μg/L.

A fact sheet on Cyanobacterial Toxins provides further infomation on sample requirements.  Algal Toxin Fact Sheet