CNCbl was obtained from Supelco and hydroxocobalamin hydrochloride (OHCbl) was purchased from Sigma-Aldrich Chemie . Sodium hydroxide, acetic acid and vitamin B12 assay medium were from Merck . In addition, the study used sodium cyanide, cobalt(II) chloride, trifluoroacetic acid (TFA), tryptone and lactate (60% w/w) from Sigma-Aldrich Chemie . All solvents were of HPLC grade . Milli-Q water was used to prepare reagents. For quantification, a stock solution of CNCbl was prepared in 25% ethanol, and the concentration was confirmed with a spectrophotometer at 361 nm