New Colorimetric Detection Method Developed for Screening Silver Ore Samples

Silver is a major precious metal that has been used for various purposes for centuries, such as currency, jewelry, and decoration. It is also an important industrial material, with uses in electronics, medicine, and photography, among others. The value of silver is influenced by supply and demand, economic conditions, and geopolitical factors. The current market price of silver fluctuates based on these factors and is closely monitored by investors and traders.

Stack of Silver Bars in the Bank Vault Abstract Background | Image Credit: © Rashevskyi Media - stock.adobe.com

Researchers at three Chinese universities (Sichuan University, Henan Normal University, and Chengdu University of Technology) have developed a new colorimetric detection method for screening silver ore samples (1).

This newly created method is based on a selective heavy atom effect-promoted photosensitization colorimetric assay, and has a visual limit of quantification (LOQ) as low as 0.2 ng/mL for Ag⁺ (1).

Screening silver ore is a challenging task. What makes this process challenging is that it requires the detection of low levels of silver in complex matrixes. Traditional methods, such as electrothermal atomic absorption spectrometry (ET-AAS), require expensive equipment and highly trained operators (1). Additionally, these methods are time-consuming and cannot be easily performed on-site. Thus, there is a need for a simple and cost-effective screening method that can be used for on-site analysis of silver ore samples, a problem that the researchers attempted to solve in this study (1).

The researchers utilized a dsDNA-staining dye (photosensitizer) and Ag⁺ ions that were spatially adjoined in close proximity in dsDNA. This leads to enhanced 1O₂ generation for photosensitized oxidation of chromogenic substrate 3,3′,5,5′-tetramethylbenzidine (TMB) (1). Because of the stable C–Ag(I)–C metallo-base pair, the C–C mismatches in dsDNA can selectively capture Ag⁺, thus allowing highly selective colorimetric detection of Ag⁺ (1).

The method was tested on certified reference material and real ore samples, and the results agreed well with those obtained by electrothermal atomic absorption spectrometry (ET-AAS) (1). Acid leaching of the samples was also adopted, and satisfactory analytical accuracy was obtained at a rough leaching efficiency of 20% (1).

The visual LOQ for ore sample analysis was about 2 g/t, making it suitable for colorimetric screening analysis of ores of different values (1). The researchers highlighted the simplicity of the method, and its potential importance for resource exploration and ore mining (1).

The study was published in the journal Analytical Chemistry (1). This new method may prove to be a valuable tool for the mining industry, providing a simple, accurate, and efficient way to screen for silver in ore samples.

Reference

(1) Wang, Y.; Zhang, H.; Hu, H.; Jiang, X.; Zhang, X.; Wu, P. Selective Heavy Atom Effect-Promoted Photosensitization Colorimetric Detection of Ag⁺ in Silver Ore Samples. Anal. Chem. 2023, ASAP. DOI: 10.1021/acs.analchem.2c05813