Trace Determination of Cyanocobalamin (Vitamin B 12 ) by Analyzing Cobalt Using a Portable Total-Reflection X-ray Fluorescence Spectrometer

: A method is presented for the detection of a trace amount of cyanocobalamin (vitamin B12) using a combination of solid-phase extraction and the measurement of cobalt in vitamin B12 by a portable total-reflection X-ray fluorescence spectrometer. Using this combination, a detection limit of 1 ng/mL was achieved for vitamin B12.