Determination of selenium using different techniques.

Area of Science:

• Analytical Chemistry
• Environmental Science

Background:

• Voltammetric methods offer a cost-effective alternative to spectroscopic techniques for selenium determination.
• Atomic absorption spectroscopy (AAS) typically measures total selenium, while voltammetry can determine specific selenium species like Se(IV).
• Combining AAS and voltammetry enables comprehensive selenium speciation analysis.

Purpose of the Study:

• To compare the analytical performance of Flame Atomic Absorption Spectroscopy (FAAS) and Graphite Furnace Atomic Absorption Spectroscopy (GFAAS) with anodic stripping square wave voltammetry (ASSWV).
• To evaluate the effectiveness of unmodified glassy carbon electrodes (GCE) and pencil graphite electrodes for selenium speciation.
• To determine individual selenium species (Se(IV), Se(VI)) in model solutions and real samples.

Main Methods:

• Comparison of FAAS, GFAAS, and ASSWV techniques.
• Utilized unmodified glassy carbon electrode (GCE) and pencil graphite electrode for voltammetry.
• Quantification of Se(IV), Se(VI), and Se(0) using stock solutions and model samples.

Main Results:

• GFAAS exhibited the lowest detection limit (5.2 μg/L), followed by ASSWV (0.57 mg/L Se(IV)) and FAAS (0.896 mg/L).
• ASSWV with GCE showed linear calibration for Se(IV) in the 1.2-9.7 mg/L range.
• FAAS was more reliable for total selenium determination in hazardous waste leachates (33-37 mg/L), while voltammetry quantified Se(IV) at 4.9-6 mg/L (14.9-17% of total Se).

Conclusions:

• Voltammetry is a viable and selective method for selenium speciation in complex matrices, complementing spectroscopic methods.
• Graphite-based electrodes offer higher sensitivity for selenium determination but require geometric stability.
• The study demonstrated the utility of combining spectroscopic and voltammetric techniques for accurate selenium speciation.