Dosage de traces de vitamines B 12

Abstract

An indirect determination of traces of vitamin B 12 is proposed; the vitamin is decomposed and the liberated cobalt is determined colorimetrically with Nitroso-R salt. 5–10 μg of B 12 can be determined. The use of tracers and internal standards decreases the error to less than 6%. Before the decomposition of the B 12 all traces of ionic cobalt are removed by means of an ion-exchange resin. The method is very sensitive and fairly selective; only homologues of B 12 containing cobalt interfere. B 12 can be determined in many pharmaceutical products.