FIA-spectrophotometric determination of nitrazepam by oxidation with a solid-phase reactor and coupling with 2,2'-dihydroxybiphenyl reagent

A new reverse flow injection system combined with a solid-phase reactor containing PbO2 was suggested for spectrophotometric determination of nitrazepam in pharmaceutical tablets. Nitrazepam was measured by coupling with a new reagent (2,2'-dihydroxybiphenyl) oxidized by forced through the reactor containing PbO2 immobilized in a polymeric matrix. The absorbance of the resultant blue colored product was measured at 635 nm, and the calibration graph for nitrazepam was linear in the 10 to 300 µg/mLconcentration range with RSD of less than 2.5% (n = 38) and a sample throughput of 40 h-1. The influence of the variables of flow system and solid-phase reactor such as composition, size of particles and length of the reactor, were studied. The proposed method was applied for determining nitrazepam in two commercial tablets without any interferences. KEY WORDS: Reverse flow injection, Nitrazepam, PbO2 reactor, Oxidative coupling Bull. Chem. Soc. Ethiop. 2019, 33(1), 183-190DOI: https://dx.doi.org/10.4314/bcse.v33i1.1