{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,7]],"date-time":"2026-01-07T23:08:48Z","timestamp":1767827328980,"version":"3.49.0"},"reference-count":11,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2017,10,12]],"date-time":"2017-10-12T00:00:00Z","timestamp":1507766400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Marine Drugs"],"abstract":"<jats:p>The absolute quantification of five toxins involved in ciguatera fish poisoning (CFP) in the Pacific was carried out by quantitative 1H-NMR. The targeted toxins were ciguatoxin-1B (CTX1B), 52-epi-54-deoxyciguatoxin-1B (epideoxyCTX1B), ciguatoxin-3C (CTX3C), 51-hydroxyciguatoxin-3C (51OHCTX3C), and ciguatoxin-4A (CTX4A). We first calibrated the residual protons of pyridine-d5 using certified reference material, 1,4-BTMSB-d4, prepared the toxin solutions with the calibrated pyridin-d5, measured the 1H-NMR spectra, and quantified the toxin using the calibrated residual protons as the internal standard. The absolute quantification was carried out by comparing the signal intensities between the selected protons of the target toxin and the residual protons of the calibrated pyridine-d5. The proton signals residing on the ciguatoxins (CTXs) to be used for quantification were carefully selected for those that were well separated from adjacent signals including impurities and that exhibited an effective intensity. To quantify CTX1B and its congeners, the olefin protons in the side chain were judged appropriate for use. The quantification was achievable with nano-molar solutions. The probable errors for uncertainty, calculated on respective toxins, ranged between 3% and 16%. The contamination of the precious toxins with nonvolatile internal standards was thus avoided. After the evaporation of pyridine-d5, the calibrated CTXs were ready for use as the reference standard in the quantitative analysis of ciguatoxins by LC\/MS.<\/jats:p>","DOI":"10.3390\/md15100309","type":"journal-article","created":{"date-parts":[[2017,10,12]],"date-time":"2017-10-12T13:06:19Z","timestamp":1507813579000},"page":"309","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":24,"title":["Quantification of Representative Ciguatoxins in the Pacific Using Quantitative Nuclear Magnetic Resonance Spectroscopy"],"prefix":"10.3390","volume":"15","author":[{"given":"Tsuyoshi","family":"Kato","sequence":"first","affiliation":[{"name":"Japan Food Research Laboratories, Tama Laboratory, Nagayama 6-11-10, Tama, Tokyo 206-0025, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Takeshi","family":"Yasumoto","sequence":"additional","affiliation":[{"name":"Japan Food Research Laboratories, Tama Laboratory, Nagayama 6-11-10, Tama, Tokyo 206-0025, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2017,10,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"228","DOI":"10.1002\/tcr.1010","article-title":"The chemistry and biological function of natural marine toxins","volume":"1","author":"Yasumoto","year":"2001","journal-title":"Chem. Rec."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"43","DOI":"10.2183\/pjab.81.43","article-title":"Chemistry, etiology, and food chain dynamics of marine toxins","volume":"81","author":"Yasumoto","year":"2005","journal-title":"Proc. Jpn. Acad. Ser. B"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"395","DOI":"10.2331\/suisan.45.395","article-title":"Ecological survey on a dinoflagellate possibly responsible for the induction of ciguatera","volume":"45","author":"Yasumoto","year":"1979","journal-title":"Bull. Jpn. Soc. Sci. Fish."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"8886","DOI":"10.1021\/ac200799j","article-title":"Detailed LC-MS\/MS analysis of ciguatoxins revealing distinct regional and species characteristics in fish and causative alga from the Pacific","volume":"83","author":"Yogi","year":"2011","journal-title":"Anal. Chem."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Ikehara, T., Kuniyoshi, K., Oshiro, N., and Yasumoto, T. (2017). Biooxidation of ciguatoxins leads to species-specific toxin profiles. Toxins, 9.","DOI":"10.3390\/toxins9070205"},{"key":"ref_6","unstructured":"U.S. Food and Drug Administration (2014, January 15). Fish and Fishery Products Hazards and Control Guidance, Available online: http:\/\/www:fda.gov\/food\/guidanceregulation\/guidancedocumentsregulatoryinformation\/seafood\/ucm2018426.htm."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"213","DOI":"10.1088\/0026-1394\/41\/3\/015","article-title":"Practical guide for accurate quantitative solution state NMR analysis","volume":"41","author":"Saito","year":"2004","journal-title":"Metrologia"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"79","DOI":"10.1007\/s00769-008-0461-z","article-title":"A new traceability scheme for the development of international system-traceable persistent organic pollutant reference materials by quantitative nuclear magnetic resonance","volume":"14","author":"Saito","year":"2009","journal-title":"Accred. Qual. Assur."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"4380","DOI":"10.1021\/ja00167a040","article-title":"Structures and configurations of ciguatoxin from the moray eel Gymnothorax javanicus and its likely precursor from the dinoflagellate Gambierdiscus toxicus","volume":"112","author":"Murata","year":"1990","journal-title":"J. Am. Chem. Soc."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1975","DOI":"10.1016\/S0040-4039(00)91978-6","article-title":"The structure of CTX3C, a ciguatoxin congener isolated from cultured Gambierdiscus toxicus","volume":"34","author":"Satake","year":"1993","journal-title":"Tetrahedron Lett."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"729","DOI":"10.2116\/analsci.32.729","article-title":"Absolute quantification of lipophilic shellfish toxins by quantitative nuclear magnetic resonance using removable internal reference substance with SI traceability","volume":"32","author":"Kato","year":"2016","journal-title":"Anal. Sci."}],"container-title":["Marine Drugs"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1660-3397\/15\/10\/309\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T18:47:03Z","timestamp":1760208423000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1660-3397\/15\/10\/309"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2017,10,12]]},"references-count":11,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2017,10]]}},"alternative-id":["md15100309"],"URL":"https:\/\/doi.org\/10.3390\/md15100309","relation":{},"ISSN":["1660-3397"],"issn-type":[{"value":"1660-3397","type":"electronic"}],"subject":[],"published":{"date-parts":[[2017,10,12]]}}}