An Improved Method for the Determination of Nicotinic Acid in Human Plasma by High-Performance Liquid Chromatography

Abstract A simple, specific, and sensitive HPLC method was developed for the determination of nicotinic acid in human plasma. Plasma is deproteinized with acetonitrile and centrifuged. The supernatant solution is evaporated and reconstituted in mobile phase. Separation is achieved using an IB-SIL CN column with a mobile phase composed of acetonitrile:methanol:water:acetic acid (700:150:150:1, v/v/v/v). Detection is by ultraviolet absorbance at 263 nm. The retention times of nicotinic acid and 6-methyl nicotinic acid (internal standard) are approximately 3.8 and 8.8 minutes, respectively. The assay is linear in concentration ranges of 100 to 10,000 ng/ml (original method) and 20 to 2,000 ng/mL (high-sensitivity method). The analysis of pooled quality controls (150, 1,250, and 7,530 ng/mL) demonstrates excellent precision with relative standard deviations (RSD) (n = 18) of 3.4%, 2.7%, and 2.8%, respectively. For the high sensitivity method, quality control pools prepared at 60, 150, and 1,250 ng/mL had RSDs...