A new method for determining isoniazid drug by flow injection analysis with a merging zone technique

This study investigated the designing of a simple and rapid flow injection (FI) system and the determination of Isoniazid in a prepared aqueous solution. The principle of the method depended on the indirect reaction of the isoniazid drug with copper(II)-neocuproine (Cu(II)-NCPR) complex after acidifying the aqueous medium. The yellow-orange and charge transfer complex had maximum absorption at 455 nm. The optimum conditions of the FIA were studied. The calibration graph of isoniazid was constructed with a linear range of 0.10 to 10.00 mg/L, and a linearity (r2) value of 0.9988. The detection and quantification limits were 0.073 and 0.221 mg/L, respectively. The molar absorptivity (ε) was 56.68×104 L/mol.cm and Sandell's sensitivity was 0.84 ×10-3 µg/cm. The manufactured local valve was characterized by inexpensive, easily running, high repeatability (n = 6) at an RSD of 2.18%, and the dead volume was zero. The dispersion coefficient values were 1.91, and 1.53 for both concentrations of 0.60, and 4.00 mg/L, respectively. The sampling rate of the analysis for the FIA system was 63.00 samples per hour. The proposed analytical flow injection method was successfully applied to standard aqueous solutions and tablets of isoniazid. Bull. Chem. Soc. Ethiop. 2025, 39(4), 601-613. DOI: https://dx.doi.org/10.4314/bcse.v39i4.1