A Convenient Colorimetric Assay Method for Determination of Vitamin B₁₂ content in Pharmaceutical Preparations

摘要

A convenient colorimetric assay method for the determination of vitamin B₁₂ content in pharmaceutical preparations has been developed. The proposed method is based on the decomposition of vitamin B₁₂ by HNO₃ followed by subsequent formation of a stable colored complex (λ _max 435 nm) between the liberated cobalt ion and Nitroso-R-salt. Commercial injectable preparations containing vitamin B₁₂ of three different manufacturers (two were single component injection and one was multi-component injection containing vitamin B_1, B₆ and B₁₂) were analyzed by the proposed method. All of them were found to meet USP limit. A recovery test was also performed which was in close agreement with that of the USP method. Different statistical parameters such as standard deviation, co- efficient of variation and confidence interval were also determined to validate the method.