title: Difference spectrophotometric assay of nitrazepam in tablet formulations.
abstract: A difference spectrophotometric procedure is described for the assay of nitrazepam in tablet formulations. The method is based on the measurement of absorbance at 282 nm of a solution of the tablet extract in 0.1 M hydrochloric acid (pH 1) relative to that of an equimolar solution in 0.1 M sodium hydroxide (pH 13). The method is precise and selective for nitrazepam in the presence of the tablet excipients and 2-amino-5-nitrobenzophenone, the principal hydrolysis product of nitrazepam. The absence of a constant isosbestic point in the difference spectrum of nitrazepam during hydrolysis in alkaline solution indicates the presence of a previously unrecognized intermediate hydrolysis product.
authors.affiliation: Department of Pharmacy, School of Pharmacy and Pharmacology, University of Strathclyde, Glasgow, UK.
authors.forename: A G
authors.initials: AG
authors.lastname: Davidson
authors.forename: H W
authors.initials: HW
authors.lastname: Li
mesh_terms: D006863:Hydrogen-Ion Concentration; D009567:Nitrazepam / Q000032:analysis*; D012996:Solutions; D013056:Spectrophotometry, Ultraviolet; D013607:Tablets
chemical_list: D012996:Solutions; D013607:Tablets; D009567:Nitrazepam