Nicotinic Acid Tablets

A. Carry out the method for thin-layer chromatography, Appendix III A, using silica gel GF₂₅₄ as the coating substance and a mixture of 8 volumes of water, 45 volumes of ethanol (96%) and 48 volumes of chloroform as the mobile phase. Apply separately to the plate 5 µL of each of the following solutions. For solution (1) shake a quantity of the powdered tablets containing 50 mg of Nicotinic Acid with 50 mL of hot ethanol (96%), filter and allow the filtrate to cool. Solution (2) contains 0.1% w/v of nicotinic acid in ethanol (96%). After removal of the plate, allow it to dry in air and examine under ultraviolet light (254 nm). The spot in the chromatogram obtained with solution (1) corresponds to that in the chromatogram obtained with solution (2).

B. Shake a quantity of the powdered tablets containing 0.1 g of Nicotinic Acid with ethanol (96%), filter and evaporate the filtrate to dryness. To the residue add 10 mg of citric acid and 0.15 mL of acetic anhydride and heat on a water bath. A reddish-violet colour is produced.

C. Triturate a quantity of the powdered tablets containing 50 mg of Nicotinic Acid with 10 mL of water and filter. To 2 mL of the filtrate add 6 mL of cyanogen bromide solution and 1 mL of a 2.5% v/v solution of aniline. A golden yellow colour is produced.