Vortex-assisted coacervative microextraction prior to UV-Vis spectrophotometry for determination of cobalt in pharmaceutical samples

Cobalt is a fundamental component in cobalamin (vitamin B12). On the other hand, It shows some adverse effects on the action of vitamin B12 when its concentration increases in human body [1,2]. Therefore, the availability of a simple and accurate method for determination of cobalt is of paramount importance. The present research introduces a novel separation-preconcentration method based on vortex-assisted coacervative microextraction to be applied as a prior step for determination of coblat in pharmaceutical samples by UV-Vis spectrophotometry. The mothod based on the extraction of coblat as its complex with 1-(2-pyridylazo)-2-naphthol (PAN) into the coacervate made up of decanoic acid reverse micelles. Effects of parameters such as concentration of tetrahydrofuran (THF) and decanoic acid, ionic strength, pH (1-4) and stirring time were investigated and optimized. Under optimum operating conditions, the calibration curve was plotted which was linear in the concnetration range of 1 to 100 μg L-1 of the cobalt. The limit of detection (LOD) and the limit of quantification (LOQ) of the method were obtained to be 0.5 μg L-1 and 1.5 μg L-1, based on 3sb/m and 10sb/m criteria, respectively. The relative standard deviation (RSD%) of the method was found to be 4%. The potential chemical interferences were studied and discussed. The the analytical applicability of the proposed method were checked through the analysis of several therapeutic and supplementary pharmaceutical preparations which showed recoveries more than 95%.