Facile and sensitive spectrophotometric determination of vanadium in various samples

Novel reactions were developed for facile, sensitive and selective rapid spectrophotometric determination of trace amounts of vanadium(V) in various samples. The methods were based on the interactions of 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) with N-(1-naphthyl)ethylenediamine dihydrochloride (NEDA) in the presence of vanadium to give blue colored derivative or on oxidation of dopamine hydrochloride (DPH) by vanadium in acidic medium and coupling with MBTH to yield pink color derivative. The blue color derivative having an absorbance maximum at 595 nm was stable for 9 days and the pink color derivative with λ_max 526 nm for 5 days. Beer's law is obeyed for vanadium in the concentration range 0.05-6.0 μg ml^-1 (blue color derivative) and 0.06-7.0 μg ml^-1 (pink color derivative), respectively. The optimum reaction conditions and other important analytical parameters were established. Interference due to various non-target ions was also investigated. The proposed methods were applied to the analysis of vanadium(V) in environmental, biological, pharmaceutical and steel samples. The performance of proposed method was evaluated in terms of Student's t-test and variance ratio F-test that indicates the significance of proposed method over reported method.