Investigating the non-enzymatic methylation of arsenite by methylcobalamin B12 using high-performance liquid chromatography on-line with inductively coupled plasma-mass spectrometry

Abstract

In this study, we have demonstrated the use of HPLC-ICP-MS as a powerful tool for studying the reaction of arsenite with methylcobalamin in the presence of glutathione. Even though this reaction has previously been investigated using radioactive ⁷³As, HPLC-ICP-MS provides considerable advantages relating to sample throughput, sensitivity, and separation efficiency of the arsenic-containing reaction products. As a result of these advantages, kinetic studies were easily conducted, potentially providing valuable insight into the reaction itself. In addition, the HPLC-ICP-MS approach allowed for the tentative identification of methylarsonous acid, an arsenic species that had escaped detection in previous studies of the same reaction. Overall, this study confirmed that methylcobalamin acts as a methylating agent for arsenite in the presence of glutathione in an abiotic environment. A series of methylated arsenic species, identified as methylarsonic acid, dimethylarsinic acid and methylarsonous acid were detected.