Direct determination of vitamin B1in seawater by solid-phase extraction and high-performance liquid chromatography quantification

Abstract

Vitamin B1 (thiamine) is one of the organic micronutrients essential for growth of algae. However, there is no direct method for the quantification of this vitamin in natural waters. Bioassay is the only protocol currently available to measure B1 in the marine environment. We have developed a new method for the direct determination of B1, along with vitamin B12 (cobalamin) in seawater. Solid-phase extraction with a column of C18 resin followed by elution with methanol was used to extract dissolved B1 from seawater. The eluted vitamin was then analyzed by reversed phase high-performance liquid chromatography (HPLC) using ammonium acetate (0.05 M) and methanol as mobile phases in pressure gradient mode. Ultraviolet-visible (UV-Vis) detection at 270 nm was used to quantify B1 levels. The calibration curve was linear from 0 to 0.60 µM and the detection limit of the protocol was on the order of 0.083 pM. This new method was successfully applied to the determination of vitamin B1 in filtered coastal seawater, porewater, and river water samples. Concentrations of vitamin B1 in those aquatic environments ranged from 0.15 nM in river to 0.75 nM in porewaters, with spike recoveries ranging from 93% to 98%.