Multi-Element Analysis of Fuel and Lubricating Oils by Simultaneous ICP-OES

Importance of the Topic

Multi-element analysis of metals in fuel and lubricating oils is critical for early detection of wear, contamination and additive loss in industrial machinery and transport systems. Monitoring trace metal concentrations enables condition-based maintenance and helps prevent unplanned downtime.

Objectives and Study Overview

The study aimed to evaluate a simultaneous inductively coupled plasma-optical emission spectrometer (ICP-OES) for rapid, accurate determination of 21 elements in various fuel oils and a certified reference lubricating oil (NIST SRM 1084a). Diluted samples in decahydronaphthalene were analyzed to validate method performance.

Methodology and Used Instrumentation

Samples were prepared by accurately weighing oil into volumetric flasks and diluting with dekalin. A Agilent Vista axial-view ICP-OES equipped with an Auxiliary Gas Module 1 added oxygen to the plasma to reduce molecular interferences and carbon deposition. Key operating parameters included power 1.3 kW, plasma gas flow 15 L/min, auxiliary gas flow 0.75 L/min and a sample uptake rate of 0.6 mL/min. The instrument’s echelle polychromator with CCD detector provided simultaneous detection of all emission lines with a typical analysis time of 105 seconds per sample.

Main Results and Discussion

The method successfully quantified 21 elements in seven fuel oils and the NIST reference sample. Measured values for the standard agreed within uncertainty with certified values, demonstrating accuracy. Oxygen addition improved detection limits and prevented carbon build-up. Sodium determination at 588.995 nm was challenged by organic background but corrected using Fast Automated Curve-fitting Technique (FACT), achieving reliable background subtraction.

• Rapid simultaneous analysis of 21 elements in ~105 seconds per sample
• Detection limits enhanced by oxygen addition to auxiliary gas
• Excellent agreement with NIST SRM 1084a certified values
• FACT enabled accurate background correction for sodium emission

Benefits and Practical Applications

This approach supports routine monitoring of wear metals and contaminants in large fleets and mining operations, extending oil change intervals and enabling timely maintenance planning. The high throughput and robust performance make it suitable for industrial quality control and research laboratories.

Future Trends and Opportunities

Advances may include automated sampling systems, enhanced data analytics for predictive maintenance, expanded element coverage, and integration with online monitoring platforms. Improved curve-fitting algorithms and miniaturized ICP systems could further streamline field deployments.

Conclusion

Simultaneous axial-view ICP-OES with oxygen-assisted plasma and FACT provides a fast, accurate, and reliable method for multi-element analysis of fuel and lubricating oils. The technique is well-suited for industrial and research environments requiring high throughput and precise monitoring of trace metals.

References

• T McKenzie Atomic Absorption Spectrophotometry for the analysis of Wear Metals in Oil Samples Varian Australia Pty Ltd AA At Work No 10 1981
• M B Knowles T Nham S J Carter A Charged-Coupled Device Detector for Atomic Emission Spectroscopy American Laboratory September 1998
• C Webb A T Zander P V Wilson G Perlis A Fast Automated Spectral Curve Fitting Technique for ICP-AES Spectroscopy May 1999 14 5 58-63