title: Determination of four forms of vitamin B12 and other B vitamins in seawater by liquid chromatography/tandem mass spectrometry.
abstract: BACKGROUND
  Vitamin B(12) is an essential nutrient for more than half of surveyed marine algae species, but methods for directly measuring this important cofactor in seawater are limited. Current mass spectrometry methods do not quantify all forms of B(12), potentially missing a significant portion of the B(12) pool.
  
  
  METHODS
  We present a method to measure vitamins B(1), B(2), B(6), B(7) and four forms of B(12) dissolved in seawater. The method entails solid-phase extraction, separation by ultra-performance liquid chromatography, and detection by triple-quadrupole tandem mass spectrometry using stable-isotope-labeled internal standards. We demonstrated the use of this method in the environment by analyzing B(12) concentrations at different depths in the Hood Canal, part of the Puget Sound estuarine system in Washington State.
  
  
  RESULTS
  Recovery of vitamin B(12) forms during the preconcentration steps was >71% and the limits of detection were <0.275 pM in seawater. Standard addition calibration curves in three different seawater matrices were used to determine analytical response and to quantify samples from the environment. Hydroxocobalamin was the main form of B(12) in seawater at our field site.
  
  
  CONCLUSIONS
  We developed a method for quantifying four forms of B(12) in seawater by liquid chromatography/mass spectrometry with the option of simultaneous analysis of vitamins B(1), B(2), B(6), and B(7). We validated the method and demonstrated its application in the field.
authors.affiliation: School of Oceanography, University of Washington, Seattle, WA, USA.
authors.forename: Katherine R
authors.initials: KR
authors.lastname: Heal
authors.forename: Laura Truxal
authors.initials: LT
authors.lastname: Carlson
authors.forename: Allan H
authors.initials: AH
authors.lastname: Devol
authors.forename: E Virginia
authors.initials: EV
authors.lastname: Armbrust
authors.forename: James W
authors.initials: JW
authors.lastname: Moffett
authors.forename: David A
authors.initials: DA
authors.lastname: Stahl
authors.forename: Anitra E
authors.initials: AE
authors.lastname: Ingalls
mesh_terms: D002853:Chromatography, Liquid / Q000379:methods*; D057230:Limit of Detection; D016014:Linear Models; D015203:Reproducibility of Results; D012623:Seawater / Q000737:chemistry*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D013696:Temperature; D014805:Vitamin B 12 / Q000032:analysis* / Q000737:chemistry; D014803:Vitamin B Complex / Q000032:analysis* / Q000737:chemistry
chemical_list: D014803:Vitamin B Complex; D014805:Vitamin B 12