title: 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.affiliation: Division of Laboratory Sciences, Centers for Disease Control and Prevention, 4770 Buford Highway, MS F44, Atlanta, Georgia 30341, USA.
authors.forename: Rudolph C
authors.initials: RC
authors.lastname: Johnson
authors.forename: Yingtao
authors.initials: Y
authors.lastname: Zhou
authors.forename: Kristen
authors.initials: K
authors.lastname: Statler
authors.forename: Jerry
authors.initials: J
authors.lastname: Thomas
authors.forename: Frederick
authors.initials: F
authors.lastname: Cox
authors.forename: Sherwood
authors.initials: S
authors.lastname: Hall
authors.forename: John R
authors.initials: JR
authors.lastname: Barr
mesh_terms: D006801:Humans; D008387:Marine Toxins / Q000737:chemistry / Q000652:urine*; D009466:Neuromuscular Blocking Agents / Q000652:urine*; D009587:Nitrogen Isotopes / Q000032:analysis; D011042:Poisons / Q000737:chemistry / Q000652:urine; D012530:Saxitoxin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000652:urine; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D008387:Marine Toxins; D009466:Neuromuscular Blocking Agents; D009587:Nitrogen Isotopes; D011042:Poisons; D012530:Saxitoxin; C034902:neosaxitoxin