Determination of isoniazid and isonicotinic acid contents in tablets by HPLC

A HPLC method for the determination of the content of Isoniazid and Isonicotinic acid in Isoniazid Tablets was established. The determination was performed on SHIM-PACK VP-ODS C₁₈ column. The mobile phase consisted of (40:60) methanol-water (0.2%Docusate Sodium) at a flow rate of 0.8ml·min^-1. The UV detection wavelength was set at 261nm and the sample size was 5μL. The linear range of isoniazid and isonicotinic acid were 10~1000μg·mL^-1 (r=0.9998) and 2~24μg·mL^-1 (r=0.9994) respectively, which showed that there was a good linear relationship in isoniazid test concentration and the isonicotinic acid test concentration respectively. The average recoveries were 99.57% (RSD=0.64%) and 98.96% (RSD=1.15%), respectively. The results demonstrated that the repeatability of the method was satisfactory and the precision of the method was satisfactory. The established method is simple, rapid and accurate, and suitable for the quality control of Isoniazid tablets. It is significant to the overall qualitative control of Isoniazid Tablets.