Optimising SPME-HPLC to determine the cyanotoxin nodularin in water: A preliminary investigation

Nodularin is a cyclic pentapeptide produced by the cyanobacterium Nodularia spumigena. This cyanotoxin is responsible for the contamination of water bodies, and potentially can lead to human illness. Current analytical techniques that quantify nodularin often require several sample preparation steps that are time consuming and use organic solvents. Our objective was to develop a simple, relatively fast and solventless method for extracting and quantifying nodularin using solid-phase microextraction (SPME) coupled with high performance liquid chromatography (HPLC). Two concentrations of nodularin (1 ppm and 10 ppb) were used to evaluate extraction capabilities of Carbowax/Templated (CW/TPR, 50 μm) coated SPME fibres. Extraction efficiency of the nodularin solutions was optimised by adjusting the salt concentration to 30% (w/w), decreasing pH to 2 and exposing the SPME fibre to the nodularin solutions for either 60 or 120 minutes, depending on nodularin concentration. Under optimised conditions, the SPME-HPLC methodology produced linear, reproducible calibration curves using fresh or seawater samples spiked with nodularin. Results suggest that SPME-HPLC could be useful in screening nodularin-contaminated water samples, with the added advantage over other traditional extraction methods of being relatively quick, simple and solventless which avoids the dangers of occupational exposure and disposal of organic solvents.