A collaborative study was conducted for the determination of paralytic shellfish poisoning (PSP) toxins in shellfish. The method used liquid chromatography with fluorescence detection after prechromatographic oxidation of the toxins with hydrogen peroxide and periodate. The PSP toxins studied were saxitoxin (STX), neosaxitoxin (NEO), gonyautoxins 2 and 3 (GTX2,3; together), gonyautoxins 1 and 4 (GTX1,4; together), decarbamoyl saxitoxin (dcSTX), B-1 (GTX5), C-1 and C-2 (C1,2; together), and C-3 and C-4 (C3,4; together). B-2 (GTX6) toxin was also included, but for qualitative identification only. Mussels, both blank and naturally contaminated, were mixed and homogenized to provide a variety of PSP toxin mixtures and concentration levels. The same procedure was followed with clams, oysters, and scallops. Twenty-one test samples in total were sent to 21 collaborators who agreed to participate in the study. Results were obtained from 18 laboratories representing 14 different countries. It is recommended that the method be adopted First Action by AOAC INTERNATIONAL.

More than 100 samples of blue-green algae products (consisting of Aphanizomenon, Spirulina, and unidentified blue-green algae) in the form of pills, capsules, and powders were collected from retail outlets from across Canada. The samples were extracted with 75% methanol in water and centrifuged to remove solids. Aliquots of the extracts along with spiked blank sample extracts were sent to each participating laboratory and independently analyzed for microcystins by enzyme-linked immunosorbent assay (ELISA), protein phosphatase inhibition assay, and by liquid chromatography–tandem mass spectrometry (LC–MS/MS) after sample cleanup using C18 solid–phase extraction. The results obtained by ELISA and LC–MS/MS agreed very well over a concentration range of about 0.5–35 μg/g. The colorimetric phosphatase results generally agreed with the other 2 methods. While the 2 biochemical assays measured total microcystin content compared with a standard of microcystin LR, the LC–MS/MS method measured specific microcystins (LA, LR, RR, YR) using external standards of these for identification and quantitation. Microcystin LR was found in all positive samples by LC–MS/MS. Microcystin LA was the only other microcystin found in the samples analyzed. These 2 microcystins represent essentially all the microcystins that were present in the extracts. Otherwise, the LC–MS/MS results would have been significantly lower than the results of the biochemical assays had other unknown microcystins been present.

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An analytical method incorporating simple liquid extraction followed by mixed mode cation exchange/reversed phase solid phase extraction and liquid chromatography-tandem mass spectrometry was developed and validated for the analysis of melamine (MEL) in liquid and powdered infant formula. The method used two different MEL stable isotope labeled internal standards to monitor analyte recoveries and to account for matrix effects. The method is sensitive (limit of quantitation of 4 ng/g), accurate, and precise (during validation, recoveries corrected by internal recovery standard averaged between 92 and 104% for all fortification levels and matrices). The method was used to analyze 94 samples of infant formula purchased from major retailers in Ottawa, ON, Canada, to examine whether or not Canadian infants are exposed to background levels of MEL. MEL was detected in 71 of the 94 products analyzed at concentrations ranging from 4.31 to 346 ng/g (median = 16 ng/g). A comparison of estimated dietary exposures to the recently recommended World Health Organization toxicological reference value for melamine suggests that the presence of low levels of MEL in infant formula purchased in Canada does not represent a health risk.