Author(s)

M. Jamaluddin Ahmed^1*, Ayesha Afrin^1,2, Yasmin Akhtar¹

¹Laboratory of Analytical Chemistry, Department of Chemistry, University of Chittagong, Chittagong, Bangladesh.
²Department of Applied Chemistry and Chemical Engineering, University of Chittagong, Chittagong, Bangladesh.

A new spectrofluorimetric reagent 2-(α-pyridyl)-thioquinaldinamide (PTQA) has been synthesized and characterized through novel reaction techniques. A very simple, ultra-sensitive and highly selective non-extractive new spectrofluorimetric method for the determination of vanadium at Pico-trace levels using 2-(α-pyridyl)-thioquinaldinamide (PTQA) has been developed. PTQA has been proposed as a new analytical reagent for the direct non-extractive spectrofluorimetric determination of vanadium (V). This novel fluorimetric reagent, PTQA becomes oxidized in a slightly acidic (0.0035 - 0.0085 M H₂SO₄) solution within vanadium (V) in 20% ethanol to produce highly fluorescent oxidized product (λ_ex = 319 nm; λ_em = 371 nm). Constant and maximum fluorescence intensities were observed over a wide range of acidity (0.0035 - 0.0085 M H₂SO₄) for the period between 5 min and 24 h. Linear calibration graphs were obtained for 0.001 - 600-μg·L^-1 of V, having a detection limit of 0.3-ng·L^-1; the quantification limit of the reaction system was found to be 3-ng·L^-1 and the RSD was 0% - 2%. A large excess of over 60 cations, anions and complexing agents (like, chloride, phosphate, azide, tartrate, oxalate, SCN^- etc.) do not interfere in the determination. The developed method was successfully used in the determination of vanadium in several Certified Reference Materials (alloys, steels, serum, bovine liver, drinking water, soil and sediments) as well as in some environmental waters (potable and polluted), biological fluids (human blood, urine, hair and milk), soil samples and food samples (vegetables, rice and wheat) solutions containing both vanadium (IV) and vanadium (V) speciation and complex synthetic mixtures. The results of the proposed method for assessing biological, food and vegetable samples were comparable with inductively coupled plasma optical emission spectroscopy (ICP-OES) and atomic-absorption spectrophotometer (AAS) was found to be in excellent agreement.

Spectrofluorimetry, Vanadium-Determination, 2-(α-Pyridyl)-Thioquinaldinamide, Environmental, Biological, Soil, Food-Samples

Ahmed, M. , Afrin, A. and Akhtar, Y. (2019) A Highly Sensitive and Selective Spectrofluorimetric Method for the Determination of Vanadium at Pico-Trace Levels in Some Real, Environmental, Biological, Soil and Food Samples Using 2-(α-Pyridyl)-Thioquinaldinamide. American Journal of Analytical Chemistry, 10, 528-561. doi: 10.4236/ajac.2019.1011038.