An assessment of vitamin B12 through determination of cobalt by X-ray fluorescence spectrometry

An X-ray fluorescence spectrometric method for the determination of vitamin B-12 in vitamin formulations is described. The method is based on the measurement of Co, the only metallic constituent of vitamin B-12. The method is simple, has no spectral interference from any element except Fe and is applicable to both solid and aqueous (dissolved solids) phases. It has a limit of the detection of 2.8 mu g/g for Co and 64 mu g/g for vitamin B-12 in solid pharmaceuticals and 2.0 mu g/g for Co and 46 mu g/g for vitamin B-12 in the liquid (aqueous) counterparts. Several commercial vitamin tablets containing vitamin B-12 in 1500-3000 mu g/g range are analysed with an accuracy of similar to 10%. Taking advantage of the water-soluble nature of vitamin B-12, some tablets have also been analysed after the ultrasonic extraction of vitamin B-12 in aqueous medium. Phosphorous, another distinguishing constituent of vitamin B-12, is not found suitable for determining the vitamin due to elevated background and spectral interferences.

Automated summary

The X-ray fluorescence spectrometric method described in the study is a simple and effective way to determine the vitamin B-12 content in vitamin formulations by measuring the Co content in vitamin B-12. The method has no spectral interference from other elements except Fe, making it a reliable technique for both solid and aqueous phases.