Ultrasound-assisted ionic liquid microextraction and colorimetric analysis for trace-level gold detection in...

Area of Science:

• Analytical Chemistry
• Environmental Science
• Materials Science

Background:

• Accurate and sensitive detection of gold ions (Au3+) is crucial for environmental monitoring and resource analysis.
• Existing methods for gold ion analysis often require complex procedures or lack sufficient sensitivity and selectivity.
• Development of rapid, efficient, and cost-effective analytical techniques for gold is an ongoing challenge.

Purpose of the Study:

• To develop a novel, precise, and targeted method for isolating, preconcentrating, and analyzing gold ions in diverse sample matrices.
• To introduce and validate a new gold-specific chelating agent, 2-amino-4-(m-tolylazo)pyridine-3-ol (ATAP), for analytical applications.
• To establish an efficient extraction and colorimetric detection system for trace amounts of Au3+.

Main Methods:

• Ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) using the ionic liquid 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide.
• Utilized 2-amino-4-(m-tolylazo)pyridine-3-ol (ATAP) as a novel, gold-specific chelating agent.
• Colorimetric detection of the gold-ATAP complex after extraction and enrichment.

Main Results:

• Achieved a linear dynamic range for Au3+ from 4.0 to 240 ng mL-1 with high molar absorptivity.
• Obtained excellent quantification and detection limits of 3.92 and 1.30 ng mL-1, respectively, with a preconcentration factor of 500.
• Demonstrated high sensitivity (Sandell sensitivity of 0.016 ng cm-2), selectivity, and minimal interference from other ions, with a low relative standard deviation (1.89%).

Conclusions:

• The proposed UA-DLLME method combined with ATAP and colorimetric detection is a fast, straightforward, and highly effective analytical approach for Au3+.
• The technique is suitable for the selective isolation and quantification of gold ions in environmental, geological, and food samples.
• This method offers a significant advancement in trace gold analysis, utilizing minimal solvent volumes and providing reliable results.