Determination of Paralytic Shellfish Toxins in Norwegian Shellfish by Liquid Chromatography with Fluorescence or Tandem Mass Spectrometry Detection.

A novel extraction and clean-up method has been developed for the determination of paralytic shellfish poisoning (PSP) toxins in shellfish samples. Raw shellfish material was extracted with an acidic acetonitrile/water (80:20, v/v) solution, whilst being homogenized. During the homogenization the sample extraction solution was cooled with ice water. Subsequently, the extract was frozen at -20 oC for at least four hours. During freezing, two layers were formed, only the lower predominantly aqueous layer was used for the determination. The final extract solution was cleaned-up using a combination of Oasis HLB and Carbograph activated carbon SPE columns. The developed extraction and clean-up methods combined with gradient elution liquid chromatography (LC)-mass spectrometry/mass spectrometry (MS/MS) has resulted in a method which can determine GTX 1-5, C 1-2, DcGTX 2-3, DcSTX, Neo, STX in a single analysis with an overall detection limit of 313 ìg/kg STX-equ shellfish. The use of the developed extraction method with the post-column high performance liquid chromatography (HPLC) with fluorescence detection (FLD) method provided an overall limit of detection of 89 ìg/kg STX-equ shellfish for the same toxins. A combination of post-column HPLC-FLD and LC-MS/MS was used to investigate the Norwegian PSP toxin profile. If was found that the PSP toxins could be detected in shellfish samples from the Norwegain coastline for ten months of the year, from March till December. The toxin profile consisted mainly of the carbamate toxins, GTX 1-4, Neo and STX, in terms of both concentrations and contribution to the overall toxicity. In addition, several of the n-sulfo-carbamoyl toxins were either detected in the samples at relatively low concentrations or their in presence the samples were indicated but, could not be confirmed by the post-column HPLC-FLD and LC-MS/MS analyses