Sprint analysis of lubricating oils using the Thermo Scientific iCAP 7600 ICP-OES

Significance of the Topic

The elemental analysis of used lubricating oils provides critical information for preventative maintenance in engines and industrial machinery. By monitoring wear metals, contaminants and additive levels, analysts can detect early signs of mechanical degradation or external contamination, minimizing downtime and reducing repair costs.

Objectives and Study Overview

This work evaluates the Thermo Scientific iCAP 7600 ICP-OES Radial coupled with an integrated Sprint sampling valve to achieve high-throughput analysis of lubricating oil samples. The goal is to reduce analysis time while maintaining the analytical performance required for routine oil monitoring in industrial and fleet maintenance laboratories.

Used Instrumentation

• Thermo Scientific iCAP 7600 ICP-OES Radial plasma spectrometer
• Integrated Sprint six-port sampling valve with vacuum and peristaltic pumps
• Standard organic sample introduction kit: V-groove nebulizer, baffled cyclonic spray chamber and 1 mm centre tube
• CETAC ASX-1400 stirring autosampler and optional APS-1650 Automated Prep Station for sample homogenization and volumetric dilutions

Methodology

Samples and calibration standards containing wear metals (Fe, Cu, Ni, Cr, etc.) and additives (Ca, P, Zn, Ba, Mg, S) were prepared in a white spirit solvent with a constant 10 % oil matrix to minimize viscosity effects. Yttrium at 20 mg/L served as an internal standard. The Sprint valve design reduces uptake and rinse times by automatically switching between load and inject positions, enabling an effective analysis pump speed of 40 rpm, 12 s uptake and zero wash time. Radial viewing height was set to 12 mm, with RF power of 1350 W and optimized gas flows. Two replicates were recorded using 1 s exposure in Sprint mode.

Results and Discussion

• Analysis time per sample was reduced to 27 s in Sprint mode, compared to around 90 s using the conventional peristaltic pump (Speed mode).
• Detection limits for most wear metals were below 1 mg/kg and for additives below 10 mg/kg, meeting industry requirements.
• Good linearity (R² > 0.9995) was achieved across single-ppm to thousands-ppm ranges by selecting two wavelengths for elements like Mg and Ba above 500 mg/kg.
• Accuracy was confirmed by recoveries within ±5 % (±10 % for boron) for a 50 mg/kg check standard. Long-term stability over four hours showed recoveries within ±10 % and RSDs < 2 %.

Benefits and Practical Applications

• High throughput enables rapid decision-making in maintenance shops and fleet management with minimal downtime.
• Reduced reagent consumption and fewer QC checks lower per-sample cost.
• Ability to handle hundreds of samples with minimal recalibration increases laboratory productivity.

Future Trends and Applications

Advances in high-throughput ICP-OES can be combined with automated sample preparation, cloud-based data analytics and machine learning for predictive maintenance. Miniaturized and online monitoring systems may further accelerate oil condition assessment directly in field operations, supporting real-time diagnostics and remote asset management.

Conclusion

The integrated Sprint sampling valve on the iCAP 7600 ICP-OES Radial delivers sub-30 s analysis times for multi-element determination in lubricating oils without compromising accuracy, precision or stability. This approach streamlines preventive maintenance workflows, reduces operational costs and supports high sample throughput in industrial laboratories.

References

• Marine Beauvir. Sprint analysis of lubricating oils using the Thermo Scientific iCAP 7600 ICP-OES. Application Note AN43161, Thermo Fisher Scientific, 2013.