Determination of vitamin B12 in equine urine by liquid chromatography - inductively coupled plasma - mass spectrometry

Regulating authorities in the racing industry have restricted the administration of potentially performance enhancing cobalt salts to horses. There are severe penalties for trainers presenting horses with elevated urine cobalt concentrations, and compliance is ensured via analysis of total urinary cobalt at thresholds of 100 μg/L. When cobalt is present as part of the cobalamin molecule it is not considered performance enhancing. This paper demonstrates that a horse can excrete a significant proportion of a commercially available vitamin B12 injection in urine without metabolic modification. A liquid chromatography - inductively coupled plasma - mass spectrometry (LC-ICP-MS) method is presented for urinary cobalt speciation. Given the serious nature surrounding performance enhancing drug offences, we conclude that presumptive positives identified by urine total cobalt measurements require further analysis to differentiate inorganic cobalt from vitamin B12.