Chaparro Laura, Ferrer Laura, Leal Luz, Cerdà Víctor
Renewable Energy and Environmental Protection Department, Advanced Materials Research Center (CIMAV), Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua, Chih. 31109, Mexico; Group of Analytical Chemistry, Automation and Environment, University of the Balearic Islands, Carretera de Valldemossa Km 7.5, E-07122 Palma de Mallorca, Spain.
Group of Analytical Chemistry, Automation and Environment, University of the Balearic Islands, Carretera de Valldemossa Km 7.5, E-07122 Palma de Mallorca, Spain.
Talanta. 2015 Feb;133:94-9. doi: 10.1016/j.talanta.2014.06.071. Epub 2014 Jul 5.
A kinetic-catalytic method for cobalt determination based on the catalytic effect of cobalt(II) on the oxidative coupling of 1,2-dihydroxyanthraquinone (alizarin) was automated exploiting multisyringe flow injection analysis (MSFIA). The proposed method was performed at pH 9.2, resulting in a discoloration process in the presence of hydrogen peroxide. The fixed-time approach was employed for analytical signal measurement. The spectrophotometric detection was used exploiting a liquid waveguide capillary cell (LWCC), of 1m optical length at 465 nm. The optimization was carried out by a multivariate approach, reaching critical values of 124 µmol L(-1) and 0.22 mol L(-1) for alizarin and hydrogen peroxide, respectively, and 67°C of reagent temperature. A sample volume of 150 µL was used allowing a sampling rate of 30h(-1). Under optimal conditions, calibration curve was linear in the range of 1-200 µg L(-1) Co, achieving a DL of 0.3 µg L(-1) Co. The repeatability, expressed as relative standard deviation (RSD) was lower than 1%. The proposed analytical procedure was applied to the determination of cobalt in cobalt gluconate and different forms of vitamin B12, cyanocobalamin and hydroxicobalamin with successful results showing recoveries around 95%.
