Development of RP-HPLC method for the determination of isoniazid in pharmaceutical dosage forms

Using UV detection and a gradient mobile phase with a NUCLEODUR 100-5 C-18 column (250x4.6mm, 5μm), a rapid, simple, and accurate high-performance liquid chromatography method was developed to determine the concentration of isoniazid in pharmaceutical dosage forms and pure solutions. The system used a UV detector set at 270 nm to identify isoniazid; it was a Shimadzu high-performance liquid chromatography system. An 80:15:5 ratio of water, methanol, and acetonitrile was employed as the mobile phase. The sample volume was 20 μL, and the mobile phase was pumped at a flow rate of 0.7 mL/min. Linearity was observed between 0.5 and 40 μg/mL, with a limit of detection of 0.1 μg/mL, recovery percentages ranging from 98.5% to 103.5%, and a relative standard deviation of less than 1.5%. No interference peaks from other additives were observed, and isoniazid demonstrated high selectivity. KEY WORDS: Analysis, Determination, High-performance liquid chromatography (HPLC), Isoniazid Bull. Chem. Soc. Ethiop. 2026, 40(1), 1-9. DOI: : https://dx.doi.org/10.4314/bcse.v40i1.1