title: Enhanced spectrophotometric determination of nicotinic acid in a sodium dodecyl sulphate micellar medium.
abstract: The spectrophotometric determination of pyridine and pyridine derivatives by means of the König reaction was studied in micellar media of sodium dodecyl sulphate (SDS), N-cetylpyridinium chloride and Triton X-100. The sensitivity was largely increased in SDS micellar medium. The attack of the pyridine ring with cyanogen bromide to produce a glutaconic aldehyde was not affected by the presence of SDS, but the yield of the coupling reaction with an arylamine to produce a polymethine dye was largely increased. In the SDS micellar medium, aniline was superior to other coupling reagents. The limits of detection (LODs) were 6 x 10(-7), 1 x 10(-6) and 5 x 10(-7)M for pyridine, pyrrol-ylmethylpyridine and nicotinic acid, respectively, and the reproducibility for 2 x 10(-5)M solutions was ca. 2%. In the absence of SDS, the LODs were 3 x 10(-6), 3 x 10(-6) and 9 x 10(-6)M, respectively, and the reproducibility was ca. 3.5%. Application was made to the determination of nicotinic acid in pharmaceuticals.
authors.affiliation: Departament de Ciències Experimentals, Escola Superior de Tecnologia i Ciències Experimentals, Universitat Jaume I, Castelló, Spain.
authors.forename: J S
authors.initials: JS
authors.lastname: Esteve-Romero
authors.forename: L
authors.initials: L
authors.lastname: Monferrer-Pons
authors.forename: G
authors.initials: G
authors.lastname: Ramis-Ramos
authors.forename: M C
authors.initials: MC
authors.lastname: García-Alvarez-Coque