Determination of four forms of vitamin B12 and other B vitamins in seawater by liquid chromatography/tandem mass spectrometry.

Rationale: 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.