Development of new efficient and cost effective liquid-liquid extractive determination method for cobalt(II): Analysis of water, alloys and nano powder

Abstract

BackgroundThe renowned biological role of cobalt is it is main component of vitamin B12, however other cobalt compounds have been listed as toxic for the environment as well as to human. MethodsVarious samples from different sources are analyzed for their cobalt(II) content by extraction followed by UV–visible spectrophotometry and compared with atomic absorption spectrophotometry. ResultsIn this article, the chromogenic reagent 2-chlorobenzaldehyde thiocarbohydrazone is introduced for extractive spectrophotometric determination of cobalt(II) from various samples. This reagent forms yellow colored 1:2:2 [Co(II)–2CBTCH–iodide] complex in dichloromethane which was extracted from an acetate buffer having pH of 4.2 in presence of potassium iodide solution which was stable up to 48 h. The absorbance of the complex exhibit peak absorbance at 400 nm. The present technique was optimized for numerous influences and the interference of other ion has also been cautiously studied. The calculated values of molar absorptivity and Sandell's sensitivity of the complex are found to be 0.3006 × 104 mol−1 cm−1 and 0.0196 µg cm−2 respectively. The technique conforms Beer's law up to 13 μg mL−1 with 0.999 correlation coefficient of the [Co(II)–2CBTCH–iodide] complex, which specifies linearity between the two variables. For five replicate determinations (n = 5), the relative standard deviation was 1.18 with the regression equations as y = 0.0672 x + 0.01 with R2 = 0.999 as the correlation coefficient. The recovery percentages were warranted the accuracy and found around 99.0%. ConclusionThe technique was successfully used to the determination of cobalt(II) in water, alloy and nano powders with acceptable results and was evaluated its performance in terms of Student ‘t’ test and Variance ‘f’ test, which indicates the significance of the present method as an inter comparison of the experimental values using AAS. The technique was also useful for analysis of alloys and synthetic mixtures.