Simultaneous Kinetic Spectrophotometric Determination of Hydrazine and Isoniazid Using H-Point Standard Addition Method and Partial Least Squares Regression in Micellar Media

The present study describes the application of simultaneous kinetic spectrophotometric determination of hydrazine (HZ) and isoniazid (INH), using H-point standard addition method (HPSAM) and partial least squares (PLS) calibration. The methods are based on the difference observed in the rate of iron (III) reduction with HZ and INH, in the presence of 2,2'-bipyridine (Bpy) and the subsequent complex formation between the resulted Fe and Bpy in a solution containing sodium dodecyl sulfate (SDS) as a micellar medium. INH and HZ can simultaneously be determined between the range of 0.08−6.0 and 1.0−80.0 μg mL, respectively. The results have shown that by the application of HPSAM, the simultaneous determination could be performed with the ratio of 1:1000 to 1:12.5 for INH-HZ. Through the HPSAM analysis, the relative standard deviations of HZ and INH were 2.5 and 1.2, respectively. The total relative standard error for applying the PLS method to 9 synthetic samples, in the concentration ranges of 0.0−20.0 μg mL of HZ and 0.5−3.0 μg mL of INH, was 3.19. Both proposed methods (PLS and HPSAM) were successfully applied to the simultaneous determination of HZ and INH in several commercially available isoniazid formulations and satisfactory results were obtained.