A new method for the determination of Vitamin B12 in seawater

Despite the environmental importance of Vitamin B12, there is no direct method for B12 quantification in natural waters. Bioassay is the only protocol currently available to measure B12 in the marine environment. Here we report a new method for the direct determination of B12 in seawater based on C18 solid-phase extraction and quantification by Reversed-Phase High-Performance Liquid Chromatography (HPLC) with an UV–Vis detector. The detection limit of the B12 protocol was of the order of 0.042 ng l^-1. The method was successfully applied to the determination of Vitamin B12 in filtered coastal seawater. Concentrations of Vitamin B12 in the coastal environment ranged 3–605 ng l^-1 with spike recoveries between 92 and 99%.