Analytical Sciences
Online ISSN : 1348-2246
Print ISSN : 0910-6340
Original Papers
Absolute Quantification of Lipophilic Shellfish Toxins by Quantitative Nuclear Magnetic Resonance Using Removable Internal Reference Substance with SI Traceability
Tsuyoshi KATOMaki SAITOMika NAGAEKazuhiro FUJITAMasatoshi WATAITomoji IGARASHITakeshi YASUMOTOMinoru INAGAKI
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2016 Volume 32 Issue 7 Pages 729-734

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Abstract

Okadaic acid (OA), a lipophilic shellfish toxin, was accurately quantified using quantitative nuclear magnetic resonance with internal standards for the development of an authentic reference standard. Pyridine and the residual proton in methanol-d4 were used as removable internal standards to limit any contamination. They were calibrated based on a maleic acid certified reference material. Thus, the concentration of OA was traceable to the SI units through accurate quantitative NMR with an internal reference substance. Signals from the protons on the oxygenated and unsaturated carbons of OA were used for quantification. A reasonable accuracy was obtained by integrating between the lower and upper 13C satellite signal range when more than 4 mg of OA was used. The best-determined purity was 97.4% (0.16% RSD) when 20 mg of OA was used. Dinophysistoxin-1, a methylated analog of OA having an almost identical spectrum, was also quantified by using the same methodology.

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© 2016 by The Japan Society for Analytical Chemistry
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