GC-MS Determination of Nicotinic Acid with Derivatization by Silanization

Sample of nicotinic acid tablet was ultrasonically extracted with pyridine and after filtration nicotinic acid in the supernatant was derivatized with hexamethyldisilazane and trimethylchlorosilane.The derivatized product was extracted with n-heptane.The extract was used for GC-MS analysis after adding ethyl benzoate as internal standard.The HP-5MS capillary column was used for GC separation and the full-scanning mode was adopted in MS determination.Linear relationship between values of peak area ratios of the nicotinic acid standard to internal standard and mass concentration of nicotinic acid was obtained in the range within 1.000 g·L-1,with detection limit (3s) of 4.54 mg·L-1.The proposed method was applied to the analysis of nicotinic acid tablets,giving values of RSD′s (n=6) in the range of 1.65%-2.89% and recovery in the range of 90.1%-93.2%.