Abstract
A new reverse flow injection system combined with a solid-phase reactor containing PbO 2 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 PbO 2 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, PbO 2 reactor, Oxidative coupling Bull. Chem. Soc. Ethiop. 2019 , 33(1), 183-190 DOI: https://dx.doi.org/10.4314/bcse.v33i1.18
Highlights
Nitrazepam (7-nitro-5-phenyl-1,3-dihydro-2H-1,4-benzo-diazepin-2-one, C15H11N3O3) belongs to the class of medications called benzodiazepines
Its therapeutic relevance and importance have encouraged the development of several methods for its determination in pharmaceutical dosage forms and biological samples
Several methods are reported for nitrazepam (NIT) determination such as reverse phase high pressure liquid chromatography (RP-HPLC) [2], liquid-liquid microextraction followed by HPLC [3], chemiluminescence [4], capillary electrophoresis [5], and ultra high performance liquid chromatography–tandem mass spectrometry [6, 7]
Summary
Nitrazepam (7-nitro-5-phenyl-1,3-dihydro-2H-1,4-benzo-diazepin-2-one, C15H11N3O3) belongs to the class of medications called benzodiazepines. The proposed single line flow injection manifold includes a reactor containing PbO2 immobilized on inert support as an oxidant. 2,2'-dihydroxybiphenyl (DHB) was injected into the stream of reduced NIT solution (using a plastic syringe) which was oxidized through the PbO2 solid phase reactor (length: 5.5 cm, particle size: 1 mm) and mixed in a 100 cm reaction coil.
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