Advances in solid phase extraction of the cyanobacterial toxin cylindrospermopsin

Abstract

Unlike other cyanotoxins, cylindrospermopsin (CYN) is often found in high concentrations in the extracellular fraction, possibly due to a higher release from the producing cells and a limited degradation once liberated. This fact demands effective recovery methods from environmental samples to guarantee a proper quantification. A reliable and simple solid phase extraction (SPE) method was obtained by the sole use of graphitized carbon cartridges and by paying special attention to both the selection of the most suitable solvent and the need of sample preparation prior to SPE. An acidified combination of dichloromethane and methanol not only showed best recoveries, but also allowed drastic reduction to the elution volumes needed with complete recovery being achieved in only 8 mL. Acidification of the sample and addition of sodium chloride are suggested as valuable improvements to the SPE method and turn out to be essential for correct and robust recovery of CYN in environmental samples of great diversity in terms of pH, DOC, and conductivity. Excellent behavior of the proposed method over a wide range of CYN loadings, applied sample volumes, and DOC loadings was also confirmed.