title: Use of a continuous flow solid-phase spectroscopic sensor using two sensing zones: determination of thiamine and ascorbic acid.
abstract: A simple, rapid, inexpensive, and automated flow-through solid-phase spectroscopic sensing device is proposed for the sequential determination of 2 vitamins: thiamine and ascorbic acid. The vitamins are concentrated on ion-exchange gels, thiamine on Sephadex SP C-25, and ascorbic acid on Sephadex QAE A-25; both solid supports are packed in 2 different flow cells. The absorbance is monitored directly on the solid phase with a double-beam spectrophotometer at 250 nm, without derivatization or additional elution. With the use of 2 carrier/self-eluting solutions (0.1 5M sodium acetate/acetic acid and 0.18M citric acid/K2HPO4) and a sample volume of 1000 microL, the sensor responds linearly in the range of 0.5-15 and 3-50 microg/mL with detection limits of 0.14 and 0.36 microg/mL for thiamine and ascorbic acid, respectively. When the method was applied to synthetic samples and pharmaceutical preparations, precise and accurate values were obtained.
authors: University of Jaén, Faculty of Experimental Sciences, Department of Physical and Analytical Chemistry, Spain.
authors: Antonio
authors: A
authors: Ruiz-Medina
authors: Pilar
authors: P
authors: Ortega-Barrales
authors: María Luisa
authors: ML
authors: Fernández-de Córdova
authors: Antonio
authors: A
authors: Molina-Díaz
mesh_terms: D001205:Ascorbic Acid / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*; D013831:Thiamine / Q000032:analysis*
chemical_list: D001205:Ascorbic Acid; D013831:Thiamine