The Performance Characteristics of Axial and Radial View in ICP-OES Analysis

Importance of the Topic

The performance of ICP-OES systems relies heavily on the configuration of the plasma viewing geometry, which directly influences sensitivity, resistance to matrix effects, and operational stability. Optimizing axial and radial views—and combining them in dual view instruments—enables laboratories to achieve accurate multi-element measurements in a variety of challenging samples, from aqueous solutions to high-solids and organic matrices.

Objectives and Study Overview

The research aims to:

• Compare the analytical figures of merit for axial, radial, and dual view configurations in ICP-OES.
• Assess the impact of an integrated gas purge design on UV transmission and long-term stability.
• Demonstrate the versatility of the Thermo Scientific iCAP 7000 Plus Series for different sample matrices.

Methodology and Instrumentation

• Instrument: Thermo Scientific iCAP 7000 Plus Series ICP-OES with dual view fore-optics and distributed purge system.
• Purge Gas System: Uniform argon or nitrogen flow in polychromator, fore-optics, and plasma interface optimized by CFD.
• Plasma Interfaces: Radial POP tubes with ceramic window to enhance UV stability; axial and dual POP configurations.
• Sample Types: Aqueous standards (50 µg/kg to 5 mg/kg), organic oil solution (1 mg/kg), and high dissolved solids salt solution (2% HNO₃, 8% NaCl).
• Sample Introduction: ESI pergo Argon Nebulizer, gas humidifier, and Teledyne CETAC ASX-560 autosampler.
• Measurement Conditions: No internal standard drift correction; normalization to first sample intensity.

Main Results and Discussion

• Sensitivity and Detection Limits: Radial view in dual mode improved detection limits for elements such as Al (167.079 nm) and P (177.495 nm).
• Long-Term Stability: Over 12 hours, recoveries for all elements remained within ±10%, with most analytes showing better than ±5% recovery; average RSD ≤1% across replicates.
• Matrix Tolerance: Radial configuration exhibited robust performance in high dissolved solids and organic matrices, minimizing signal drift and interface fouling.
• Dynamic Range: Dual view instruments maintained a wide calibration range, leveraging axial sensitivity for low concentrations and radial tolerance for high-level samples.

Benefits and Practical Applications

The optimized dual view ICP-OES system delivers:

• Enhanced throughput: Reduced need for recalibration and re-analysis lowers per-sample cost.
• Versatility: One platform for trace-level detection and complex, high-solid content samples.
• Operational Efficiency: Lower gas consumption and minimal accessory requirements reduce running costs.
• Reliability: Stable signals over extended runs support demanding QA/QC workflows.

Future Trends and Opportunities

Emerging directions in ICP-OES will focus on:

• Advanced optics and purge designs guided by fluid dynamics simulations.
• Automation and integration with laboratory information management systems (LIMS) for real-time data analysis.
• Miniaturized and portable ICP-OES solutions for field-based testing.
• Expansion of dual view technology to support ultra-trace analysis in increasingly complex matrices.

Conclusion

The Thermo Scientific iCAP 7000 Plus Series demonstrates how a coordinated axial and radial viewing approach—augmented by a distributed purge gas system—achieves superior sensitivity, matrix tolerance, and stability. This innovation supports a broad spectrum of analytical tasks, enhancing efficiency and reliability in modern laboratories.

References

1. TN43333 Thermo Scientific iCAP 7000 Plus Series ICP-OES: Innovative optical design.
2. SP43438 Thermo Scientific iCAP 7000 Plus Series ICP-OES: Purged optical path plasma interfaces.
3. TN43259 Highly stable performance of the Thermo Scientific iCAP 7000 Plus Series ICP-OES Radial.