Analysis of Additive Elements in Lubricating Oil Using ICPE-9000

Importance of the Topic

Analysing metallic additive elements in lubricating oils is critical for ensuring oil performance, reducing engine wear, and maintaining quality control across automotive and industrial applications. Precise determination of elements such as B, Ca, Mg, Mo, P and Zn supports formulation optimization and monitoring of degradation processes during high-temperature operation.

Study Objectives and Overview

This study demonstrates the application of Shimadzu’s ICPE-9000 inductively coupled plasma atomic emission spectrometer for simultaneous multielement analysis of commercial engine oil, automatic transmission fluid (ATF) and gear oil. The main goals were to assess instrument performance, evaluate dilution accuracy, and verify analytical precision and stability.

Methodology

• Sample Preparation: Each oil sample (1 g) was diluted 100-fold in xylene. One gear oil sample underwent further dilution (500-fold). Yttrium (1 mg/L) served as an internal standard.
• Calibration: Standard solutions were prepared from SPEX and CONOSTAN oil-base multielement mixtures diluted in xylene, matching sample matrix and internal standard concentration.
• Analysis: Quantitation by calibration-curve method with internal standard. Dilution test compared values from 100-fold and 500-fold dilutions to assess recovery.

Instrumentation

• Instrument Model: Shimadzu ICPE-9000
• RF Power: 1.4 kW
• Gas Flow Rates: Plasma 16 L/min, Auxiliary 1.4 L/min, Carrier 0.7 L/min
• Sample Introduction: Nebulizer (type 10), Co-axial spray chamber, Radial observation torch

Main Results and Discussion

• Quantitative Analysis: Six oil samples (three engine oils, one ATF, two gear oils) were tested. Concentrations (µg/g) ranged: Ca (67–2920), Zn (8.6–2640), P (278–3320), B (9.1–2040), Mg (1.0–737), Mo (60–96).
• Recovery and Precision: Dilution tests on engine oil yielded 96–104% recovery. Over three hours, relative standard deviations for all elements were ≤1%.
• Spectral Performance: Emission lines for Ca (315.887 nm), Mo (202.030 nm), Zn (202.548 nm) were well resolved. Calibration curves showed excellent linearity (r > 0.99996).
• Carbon Management: The plasma torch design prevented carbon deposition, removing the need for oxygen addition even with organic solvents.

Benefits and Practical Applications

The ICPE-9000 system enables rapid, simultaneous determination of multiple additive elements with high accuracy and stability. It supports quality assurance in lubricant manufacture, additive monitoring, contamination assessment, and maintenance planning for engines and machinery.

Future Trends and Opportunities

• Integration of online monitoring for real-time lubrication analysis.
• Extension to trace-level contaminant detection and wear particle profiling.
• Automation and advanced data analytics using machine learning.
• Coupling with mass spectrometry for speciation studies and characterization of non-metallic additives.

Conclusion

The Shimadzu ICPE-9000 ICP emission spectrometer offers efficient and reliable multielement analysis of lubricant additives with high recovery, exceptional repeatability, and minimal maintenance. This capability enhances quality control and research in lubrication science.