water (9 + 1, v/v). The crude extract was then
centrifuge d (3400 g, 10 min) and 2 ml of the
supernatant was washed with 5 ml hexane. After
centrifugation, 1 ml of the lower layer was transferred
to an autosampler vial for LC–MS/MS analysis.
Determination of the proportion of esterified forms of
okadaic acid (OA) and dinophysis toxins (DTXs) in
sample extracts was performed before and after
alkaline hydrolysis.