| DOI: https://doi.org/10.29090/psa.2018.03.161 | Pharm Sci Asia 2018; 45(3), 161-173 |
Simultaneous detection of three biotoxins causing diarrhetic shellfish poisoning (okadaic acid, dinophysistoxin-1, dinophysistoxin-2) in oyster by LC-MS/MST.T.T. Vuong, L.D. Chi*, L.T.H. Hao
1 Department of Analytical Chemistry and Toxicology, Ha Noi University of Pharmacy, Ha Noi, Vietnam
2 National Institute of Food Control, Ha Noi, Vietnam
A LC-MS/MS method was developed for simultaneous determination of okadaic acid, dinophysistoxin-1 and dinophysistoxin-2 in shellfish. The development of such a method was necessary for specific determination of these toxins, which was not assured by available officical methods in Vietnam using mouse bioassay and HPLC with fluorescent detection. Chromatographic separation of toxins was done on a ultra performance C18 column (50 mm x 2.1 mm; 1.8 µm) and isocratic elution was carried out with a acetonitrile – water mixture (65 : 35, v/v) containing 0.1% formic acid and 2.0 M of ammonium formate as mobile phase. The detection of toxins was done with electrospray ionization in negative mode, with the ESI ion source set at 5500 V, using one precursor ion (m/z = 803 for okadaic acid and dinophysistoxin-2, m/z = 817 for dinophysistoxin-2) and two product ions (m/z = 563 and 255) for identification of each toxin and the intensity of product ion m/z = 255 for quantitative determination of each toxin. The method was fully validated and proved to be reliable for intended purpose. The method was applied to analyze 39 oyster samples collected in Thanh Hoa province (Vietnam), in which 6 samples contained trace amounts of okadaic acid (3.1 – 9.5 ppb), 2 other samples contained trace amounts of dinophysistoxin-2 (4.4 and 6.4 ppb). The toxin detection in oyster showed a seasonal variation with higher frequency in dry season. No oyster sample was detected with toxin level higher than accepted limit (160 ppb).
Keyword:
Biotoxin, Oyster, Diarrhetic shellfish poisoning, Natural products, LC-MS/MS
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