Rapid Postcolumn Methodology for Determination of Paralytic Shellfish Toxins in Shellfish Tissue
Abstract:A rapid liquid chromatographic (LC) method with postcolumn oxidation and fluorescence detection (excitation 330 nm, emission 390 nm) for the determination of paralytic shellfish toxins (PSTs) in shellfish tissue has been developed. Extracts prepared for mouse bioassay (MBA) were treated with trichloroacetic acid to precipitate protein, centrifuged, and pH-adjusted for LC analysis. Saxitoxin (STX), neoSTX (NEO), decarbamoylSTX (dcSTX), and the gonyautoxins, GTX1, GTX2, GTX3, GTX4, GTX5, dcGTX2, and dcGTX3, were separated on a polar-linked alkyl reversed-phase column using a step gradient elution; the N-sulfocarbamoyl GTXs, C1, C2, C3, and C4, were determined on a C-8 reversed-phase column in the isocratic mode. Relative toxicities were used to determine STX-dihydrochloride salt (diHCl) equivalents (STXeq). Calibration graphs were linear for all toxins studied with STX showing a correlation coefficient of 0.999 and linearity between 0.18 and 5.9 ng STX-diHCl injected (equivalent to 3.9128 g STXeq/100 g in tissue). Detection limits for individual toxins ranged from 0.07 g STXeq/100 g for C1 and C3 to 4.1 g STXeq/100 g for GTX1. Spike recoveries ranged from 76 to 112 in mussel tissue. The relative standard deviation (RSD) of repeated injections of GTX and STX working standard solutions was <4. Uncertainty of measurement at a level of 195 g STXeq/100 g was 9, and within-laboratory reproducibility expressed as RSD was 4.6 using the same material. Repeatability of a 65 g STXeq/100 g sample was 3.0 RSD. Seventy-three samples were analyzed by the new postcolumn method and both AOAC Official Methods for PST determination: the MBA (y = 1.22x + 13.99, r2 = 0.86) and the precolumn LC oxidation method of Lawrence (y = 2.06x + 12.21, r2 = 0.82).
Document Type: Research Article
Affiliations: 1: Canadian Food Inspection Agency, Dartmouth Laboratory, 1992 Agency Dr, Dartmouth, Nova Scotia, B3B 1Y9, Canada. 2: National Research Council of Canada, Institute for Marine Bioscience, 1411 Oxford St, Halifax, Nova Scotia, B3H 3Z1, Canada.
Publication date: May 1, 2008
- The Journal of AOAC INTERNATIONAL publishes refereed papers and reviews in the fields of chemical, biological and toxicological analytical chemistry for the purpose of showcasing the most precise, accurate and sensitive methods for analysis of foods, food additives, supplements and contaminants, cosmetics, drugs, toxins, hazardous substances, pesticides, feeds, fertilizers and the environment available at that point in time. The scope of the Journal includes unpublished original research describing new analytical methods, techniques and applications; improved approaches to sampling, both in the field and the laboratory; better methods of preparing samples for analysis; collaborative studies substantiating the performance of a given method; statistical techniques for evaluating data. The Journal will also publish other articles of general interest to its audience, e.g., technical communications; cautionary notes; comments on techniques, apparatus, and reagents.
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