Modification of the methylene blue method for spectrophotometric selenium determination

Area of Science:

• Analytical Chemistry
• Environmental Chemistry
• Spectrophotometry

Background:

• Accurate determination of selenium(IV) is crucial for environmental monitoring.
• Existing spectrophotometric methods for Se(IV) require optimization for sensitivity and accuracy.
• The catalytic effect of Se(IV) in Methylene Blue reduction by sulfide is a known analytical principle.

Purpose of the Study:

• To modify and optimize a spectrophotometric method for Se(IV) determination.
• To investigate and control variables affecting the Methylene Blue reduction reaction.
• To improve the lower determination limit and linear range for accurate selenium analysis.

Main Methods:

• Spectrophotometric analysis utilizing the catalytic effect of Se(IV) on Methylene Blue reduction by sulfide.
• Systematic investigation of parameters including reagent concentrations, pH, temperature, and reaction times.
• Validation of the optimized method with environmental samples and comparison to standard methods.

Main Results:

• Optimized analytical conditions significantly decreased the determination limit for Se(IV).
• Achieved a lower limit range of 15-75 µg/L with 3% relative standard deviation.
• Successfully applied the method to environmental samples, demonstrating its practical applicability and overcoming interferences.

Conclusions:

• The modified spectrophotometric method provides a sensitive and accurate approach for Se(IV) determination.
• Optimization of reaction variables is key to achieving lower detection limits and reliable results.
• The proposed method is suitable for analyzing selenium in environmental matrices.