Spectrophotometric Determination of Niacin Using 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone

Abstract

A simple and sensitive spectrophotometric method is developed for the assay of niacin. The method is based on charge transfer complexation reaction of niacin as n-electron donor with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone as π-acceptor to form highly coloured charge transfer complex with 1:1 stoichiometry. The coloured product was quantified at 464 nm under the optimized experimental conditions. Beer’s law is obeyed over the concentration range of 5-130 μg/mL. The apparent molar absorptivity is calculated to be 1.02 × 103 L mol-1cm-1. Corresponding Sandell’s sensitivity is 1.85, detection and quantification limits are also reported. The proposed method is applied successfully to the determination niacin in pure and commercial forms with good average recovery of 97.82 % and low relative standard deviation of < 1. Statistical comparison of the results was performed using the student’s t-test and f-test at 95 % confidence level.