Optimization of the preconcentration of selenium iv on palladium nanoparticles (PdNPs), using multivariate analysis for the inorganic speciation of selenium in environmental water samples

Abstract

A simple method for the characterization and quantification of ultratrace quantities of Se(IV) in environmental water samples by preconcentration of selenium(IV) on PdNPs was optimized by employing the multivariate strategy. 12-run Plackett–Burman factorial design experiments were carried out to identify and the central 2³ + star orthogonal composite design was used to optimize the relevant experimental factors. Sodium borohydride (NaBH₄) was used to reduce Se(IV) to Se(0) and also to generate PdNPs. The PdNPs were collected and dissolved in a minimum amount of nitric acid and selenium was quantified by ETAAS. Se(VI) in the sample was reduced to Se(IV) and the concentration of Se(VI) was the difference between the concentrations of Se(IV) and total Se(VI) + Se(IV). The standard addition studies of Se(IV) and Se(VI) at the low, mid and high concentration levels of the calibration curve indicated recoveries between 97 and 104%. The detection limit and the preconcentration factor (PF) for the estimation of selenium employing this methodology were 0.025 μg L⁻¹ and 100 respectively. The adsorption capacity of PdNPs in the present study for Se(0) was found to be 28 mg g⁻¹. The proposed procedure was validated by applying it for the determination of the content of total Se in Certified Reference Material BND 701-02 (NPL, India) and applied for the determination of sub ppm to ppm levels of Se(IV) and Se(VI) in ground water samples from the Nawanshahar–Hoshiarpur region, Punjab, India.