Matrix effect on paralytic shellfish toxins quantification and toxicity estimation in mussels exposed to Gymnodinium catenatum

• Published in: Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment Chemistry, analysis, control, exposure & risk assessment, 2010-12, Vol.27 (12), p.1724-1732
• Main Authors: Botelho, M.J., Vale, C., Mota, A.M., Rodrigues, S.M., Costa, P.R., Simões Gonçalves, M.L.S.
• Format: Article
• Language: English
• Subjects: Algorithms; Animals; Atlantic Ocean; Biological and medical sciences; Calibration; Carbamates - analysis; Chemical compounds; Chromatography; Chromatography, High Pressure Liquid; Dinoflagellida - metabolism; Fish and seafood industries; Food industries; Food Safety; Fundamental and applied biological sciences. Psychology; Gymnodinium catenatum; Harmful Algal Bloom; LC-FLD; Limit of Detection; Marine; Marine Toxins - analysis; Mollusks; Mytilus - chemistry; Mytilus - microbiology; Mytilus galloprovincialis; Oxidation-Reduction; paralytic shellfish poisoning; phycotoxins; Portugal; Reproducibility of Results; saxitoxin; Shellfish; Shellfish - adverse effects; Shellfish - analysis; Shellfish - microbiology; Shellfish Poisoning - prevention & control; Solid Phase Extraction; Toxicity; Toxins
• ISSN: 1944-0049; 1944-0057
• DOI: 10.1080/19440049.2010.525753

Paralytic shellfish toxins were quantified in whole tissues of the mussel Mytilus galloprovincialis exposed to blooms of the dinoflagellate Gymnodinium catenatum in Portuguese coastal waters. A validated liquid chromatography method with fluorescence detection, involving pre-chromatographic oxidation was used to quantify carbamoyl, N-sulfocarbamoyl and decarbamoyl toxins. In order to test for any matrix effect in the quantification of those toxins, concentrations obtained from solvent and matrix matched calibration curves were compared. A suppression of the fluorescence signal was observed in mussel extract or fraction in comparison to solvent for the compounds dcGTX2 + 3, GTX2 + 3 and GTX1 + 4, while an enhancement was found for C1 + 2, dcSTX, STX, B1, dcNEO and NEO. These results showed that a matrix effect varies among compounds. The difference of concentrations between solvent and matrix matched calibration curves for C1 + 2 (median = 421 ng g −1 ) exceeded largely the values for the other quantified compounds (0.09-58 ng g −1 ). Those differences were converted into toxicity differences, using Oshima toxicity equivalence factors. The compounds C1 + 2 and dcNEO were the major contributors to the differences of total toxicity in the mussel samples. The differences of total toxicity were calculated in ten mussel samples collected during a 10-week blooming period in Portuguese coastal lagoon. Values varied between 53 and 218 µg STX equivalents kg −1 . The positive differences mean that the estimated toxicity using solvent calibration curves exceed the values taking into account the matrix. For the toxicity interval 200-800 µg STX equivalents kg −1 an increase was found between 44 and 28%.