Estabilidade de Saxitoxinas GTX 2/3, dc-GTX 2/3 e C1/2 em água de abastecimento e impactos na validação de método analítico

Abstract

Several reports indicate that saxitoxin-producing cyanobacteria are increasingly present in lakes in Brazil and worldwide. Nevertheless, most analytical methods reported in the literature are focused on the analysis of marine shellfish, leaving methods for drinking water understudied. This study had as objectives to validate an analytical methodology for quantification of saxitoxins GTX2/3, dc-GTX2/3 and C1/2 using high performance liquid chromatography and verify the impact of the toxins stability in the process. Toxins C1/2 suffered rapid degradation, which prevented the completion of its validation. For the other toxins, the method proved to be selective, efficient, accurate, precise and robust, except for the low concentrations. Despite the significant reduction of the limit of quantification as compared to recent literature, they were still above the amount allowed by MS 2914/2011 for drinking water, suggesting that incorporation of a pre-concentration step is necessary. The results also suggest that, due to the instability of these toxins, their detection in natural or treated waters can be compromised if the collection and preservation procedures do not follow appropriate technique.