Analysis of platinum group metals with the Thermo Scientific iCAP 7400 ICP-OES

Significance of the Topic

The platinum group metals (PGMs) are critical in modern industry due to their unique catalytic, electrical and anti-corrosive properties. Their rarity and high value make reliable quantification essential for applications ranging from automotive converters to electronics and jewelry.

Study Objectives and Overview

This study evaluates the performance of the Thermo Scientific iCAP 7400 ICP-OES Duo for direct analysis of PGMs in samples containing high concentrations of base metals. The goal is to demonstrate accurate measurements without prior matrix separation and to compare favorably with traditional radial instruments.

Methodology and Instrumentation

Sample Preparation

• Four 0.25 g aliquots of PGM mixtures with high Ni, Cu, Co, Fe and S levels
• Microwave digestion using 10 mL HCl and 1 mL HNO3 at 180 °C for 30 min
• Dilution to 100 mL with deionized water
• Calibration standards at 0, 1 and 10 mg·kg-1 for Pt, Pd, Rh, Au and Ru

Instrumental Setup

• Thermo Scientific iCAP 7400 ICP-OES Duo with aqueous sample introduction kit
• Glass concentric nebulizer and glass cyclonic spray chamber
• High-resolution Echelle optics and fourth-generation CID detector
• Pump speed 50 rpm, RF power 1150 W, nebulizer gas 0.65 L·min-1, auxiliary gas 0.5 L·min-1, coolant gas 12 L·min-1
• Axial plasma viewing for all elements

Wavelength Selection

• Gold 267.595 nm
• Palladium 340.458 nm
• Platinum 265.945 nm
• Rhodium 343.489 nm
• Ruthenium 267.876 nm

Main Results and Discussion

Calibration curves exhibited excellent linearity (r2 >0.999) up to 10 mg·kg-1 and extended to at least 500 mg·kg-1 in radial view. High base metal concentrations did not interfere when utilizing high resolution. Replicate analyses matched accepted values within ±2 standard deviations, confirming accuracy despite sample inhomogeneity.

Benefits and Practical Applications

The method allows simultaneous determination of multiple PGMs in complex matrices without pre-separation. The advanced detector offers low noise and high sensitivity, ideal for quality control in catalyst manufacturing, environmental testing and precious metal recovery.

Future Trends and Opportunities

Integration of automated plasma optimization can further streamline analysis. Expanding dynamic range through radial viewing modes and developing enhanced interference correction algorithms will improve versatility. Applications may extend to electronic waste and spent catalyst evaluation.

Conclusion

The Thermo Scientific iCAP 7400 ICP-OES Duo delivers robust and precise PGM analysis in high-matrix samples, providing a reliable alternative to conventional radial instruments and supporting diverse industrial quality assurance needs.

Reference

• US Geological Survey. Mineral Commodity Summaries: Platinum Group Metals.