A validated analytical method to measure metals dissolved in deep eutectic solvents.

Area of Science:

• Analytical Chemistry
• Materials Science
• Metallurgy

Background:

• Deep eutectic solvents (DES) are emerging as environmentally friendly alternatives in solvometallurgical processing.
• Accurate metal quantification in DES is essential for efficient and selective metal recovery.
• Existing analytical methods often fail to provide reliable results in complex DES matrices.

Purpose of the Study:

• To develop and validate a robust analytical method for quantifying eleven metals in DES using MP-AES.
• To assess the method's performance across various DES matrices, including those with oxidants.
• To establish the method's suitability for the demands of solvometallurgical applications.

Main Methods:

• Development and validation of a microwave plasma atomic emission spectrometry (MP-AES) method.
• Analysis of eleven metals (Li, Mg, Fe, Co, Ni, Cu, Zn, Pd, Al, Sn, Pb) in choline chloride-based DES.
• Validation parameters included linearity, LOD, LOQ, accuracy, precision, and selectivity across three DES matrices.

Main Results:

• The validated method demonstrated excellent linearity, accuracy (95.67-108.40% recovery), and precision (<10% relative standard deviation).
• Achieved limits of detection (LOD) and quantification (LOQ) comparable to aqueous matrices, with Cu having the lowest LOD (0.003 ppm) and Mg the highest (0.07 ppm).
• Significant quantification errors (>140%) were observed without the proposed method, highlighting its necessity for accurate DES analysis.

Conclusions:

• The developed MP-AES method is the first validated technique for metal analysis in DES, crucial for solvometallurgy.
• The method ensures accurate and precise metal quantification in diverse DES, overcoming limitations of standard analytical approaches.
• This validated method will significantly contribute to the advancement and successful implementation of solvometallurgical processing.