Amnesic Shellfish Poisoning Toxins in Shellfish: Estimation of Uncertainty of Measurement for a Liquid Chromatography/Tandem Mass Spectrometry Method
Authors: Holland, Patrick T.; McNabb, Paul; Selwood, Andrew I.; Neil, Tracey
Source: Journal of AOAC International, Volume 86, Number 5, September 2003 , pp. 1095-1100(6)
Publisher: AOAC International
Abstract:A liquid chromatography/mass spectrometry (LC/MS) method for amnesic shellfish poisoning toxins in shellfish was developed and validated. Tissue homogenate (4 g) was extracted with 16 mL methanol–water (1 + 1, v/v). Dilution into acetonitrile–water (1 + 9, v/v) was followed by C18 solid-phase extraction cleanup. Domoic acid (DA) and epi-domoic acid were determined by LC/MS/MS with electrospray ionization and multiple reaction monitoring. External calibration was performed with dilutions of a certified reference standard. Advantages of this method include speed, lower detection limits, and a very high degree of specificity. The LC/MS response was highly linear, and there were no significant interferences to the determination of DA. Formal method validation was performed on 4 shellfish species. Fortification studies gave recoveries (mean ± SD; n = 24) of 93 ± 14% at 1 mg/kg, and 93.3 ± 7.6% at 20 mg/kg over all the species. Analysis of a mussel certified reference material showed the bias as <5%. The limits of detection and quantitation were 0.15 and 0.5 mg/kg, respectively. Routine application of the method over 4 months gave a recovery for the QC sample (1 mg/kg fortified blank mussel homogenate) run with each batch of 88.9 ± 5.5% (mean ± SD; n = 37). The total uncertainty of measurement results were estimated as 0.12 (12%) at 0.25–5 mg/kg and 0.079 (7.9%) at 5–50 mg/kg. The major contribution to the uncertainty was the repeatability of the LC/MS determination, probably arising from subtle matrix effects.
Document Type: Research Article
Affiliations: Cawthron Institute, Private Bag 2, 98 Halifax St E., Nelson, New Zealand
Publication date: September 2003
- 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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