Quantification of saxitoxin and neosaxitoxin in human urine utilizing isotope dilution tandem mass spectrometry.
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.
Johnson
Rudolph C
RC
Division of Laboratory Sciences, Centers for Disease Control and Prevention, 4770 Buford Highway, MS F44, Atlanta, Georgia 30341, USA.
Zhou
Yingtao
Y
Statler
Kristen
K
Thomas
Jerry
J
Cox
Frederick
F
Hall
Sherwood
S
Barr
John R
JR
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*
D008387:Marine Toxins; D009466:Neuromuscular Blocking Agents; D009587:Nitrogen Isotopes; D011042:Poisons; D012530:Saxitoxin; C034902:neosaxitoxin