multivariate experimental design for construction of a new selective optical sensor for determination of cobalt in water samples

Abstract: cobalt is a rare metal that has a variety of commercial, industrial and military applications, and it is an important essential element in the performance of many biological processes, such as in the molecular structure of vitamin b12 [1, 2]. this research study is focused on the fabrication of a new, highly selective and simple optical membrane for the determination of cobalt (ii) ions in aqueous solutions. to eliminate the influence of the concomitants species and increase the selectivity in the determination of cobalt (ii) in real samples, it was first oxidized using a hydrogen peroxide (h2o2) solution. the obtained cobalt (iii) ions were then determined by recording the absorbance intensity of the new selective and sensitive thin optically transparent sensor. in the optical sensor, 1-nitroso-2-naphthol (1n2n) was used as the selective ligand. 1n2n is used as a sensitive, selective and stable complexing ligand that changes the absorbance of the transparent membrane in the presence of cobalt (iii). the ready-made optical sensor displayed good reproducibility and relatively long lifetime and stability with appropriate linear response from 0.1 to 5.0 mg l-1. its detection limit was obtained 0.03 mg l-1. further investigations were evaluated intra-day and inter-day precision (rsd %) 2.76-4.46% and 0.89-5.39%, respectively and the mean percentage relative error (re %), were in the 1.89 to 3.41 range. the results indicated that the presented method could be successfully used to determine cobalt (ii) in different water samples including tap water, seawater and spring water, without any pretreatment.