Quantification of saxitoxin and neosaxitoxin in human urine utilizing isotope dilution tandem mass spectrometry.

Abstract

Saxitoxin and neosaxitoxin are potent neurotoxins that can cause paralytic shellfish poisoning when consumed. A new assay is presented here to quantify saxitoxin (STX) and neosaxitoxin (NEO) in human urine samples. Sample preparation of 500-microL samples included the use of weak-cation-exchange solid-phase extraction in a multiplexed 96-well format. Extracts were preconcentrated and analyzed via 10-min hydrophilic interaction liquid chromatography followed by electrospray ionization. Protonated molecular ions were quantified via multiple reaction monitoring mode in a Qtrap mass spectrometer. The method uses novel 15N7-isotopically enriched STX and NEO internal standards. Method validation included the characterization of two enriched urine pools. The lowest reportable limits for STX and NEO were 4.80 and 10.1 ng/mL, respectively, using both quantification and confirmation ions. These two toxins were not detected in a reference range of humans who consumed seafood in the preceding 72 h, suggesting that few false positives would occur when trying to identify people exposed to STX or NEO.

• Authors: Rudolph C Johnson, Yingtao Zhou, Kristen Statler, Jerry Thomas, Frederick Cox, Sherwood Hall, John R Barr
• Journal: Journal of analytical toxicology (J Anal Toxicol) 2009 Jan-Feb Vol. 33 Issue 1 Pg. 8-14 ISSN: 0146-4760 [Print] England
• PMID: 19161664 (Publication Type: Journal Article, Validation Study)

Chemical References

• Marine Toxins
• Neuromuscular Blocking Agents
• Nitrogen Isotopes
• Poisons
• Saxitoxin
• neosaxitoxin

Topics

• Humans
• Marine Toxins (chemistry, urine)
• Neuromuscular Blocking Agents (urine)
• Nitrogen Isotopes (analysis)
• Poisons (chemistry, urine)
• Saxitoxin (analogs & derivatives, chemistry, urine)
• Spectrometry, Mass, Electrospray Ionization (methods)
• Tandem Mass Spectrometry (methods)