Analysis of Additive Elements, Wear Metals, and Contaminants in Used Lubricating Oil According to ASTM D5185: ICPE-9820

Importance of the Topic

Used engine and industrial lubricating oils accumulate wear metals, additive elements and environmental contaminants during operation. Monitoring these elements provides critical insight into equipment condition, helps prevent catastrophic failure, and supports effective maintenance scheduling. ASTM D5185 standardizes inductively coupled plasma atomic emission spectrometry (ICP-AES) methods for quantifying 22 key elements in spent lubricants, making reliable analysis both possible and practical.

Objectives and Study Overview

This study evaluates the performance of the Shimadzu ICPE-9820 multi-type ICP-AES for analysis of additive elements, wear metals and contaminants in used automotive oil according to ASTM D5185. A comparison was made between a sample of oil used for approximately 4,000 km and the same unused lubricant. Key aims included assessing linearity, accuracy (spike-and-recovery), precision (dilution test) and detection limits across 22 elements ranging from aluminum to zinc.

Methodology and Instrumentation

Sample Preparation:

• Approximately 10 g of used or unused oil diluted to 100 mL with kerosene.
• Calibration standards prepared from oil-based multi-element and single-element solutions; internal standard yttrium added to all samples at a fixed concentration.
• Spike-and-recovery test at 5 mg/L for low-concentration elements; 50-fold dilution test for high-concentration elements.

Instrumentation:

• Shimadzu ICPE-9820 ICP-AES with vertically oriented plasma torch to minimize carbon deposition.
• Vacuum spectrometer enabling analysis of vacuum-UV lines (e.g., sulfur) without expensive high-purity purge gases.
• Operating conditions included 1.40 kW RF power, 16.0 L/min plasma gas, 1.40 L/min auxiliary gas, 0.70 L/min carrier gas and an organic-solvent compatible nebulizer with support ring.

Main Results and Discussion

Linearity:

• Calibration curves for Fe, Mg and S exhibited correlation coefficients of 0.99999 to 1.00000 over relevant concentration ranges, indicating excellent linear response.

Accuracy and Precision:

• Spike-and-recovery in used oil yielded recoveries of 99–103% for low-level elements.
• Dilution tests on high-concentration elements returned values close to 100%, confirming proportional response on dilution.

Detection Limits:

• Limits of detection ranged from 0.002 to 0.6 μg/g, sufficient to quantify trace wear metals and additives.

Unused oil samples showed element concentrations below detection limits or at expected background levels, validating the method’s selectivity.

Benefits and Practical Applications

Using the ICPE-9820 offers several advantages:

• Stable analysis of organic solvent-diluted oil without oxygen addition, reducing complexity and cost.
• Minimized carbon deposition leads to extended maintenance intervals.
• Vacuum spectrometer capability enables low-cost analysis of vacuum-UV wavelengths, including sulfur, without specialized purge gases.
• Compliance with ASTM D5185 and Japan Petroleum Institute standards for engine health monitoring in automotive and industrial settings.

Future Trends and Potential Applications

Emerging directions include integration with online oil monitoring systems for real-time diagnostics, expansion to additional trace elements and contaminants, coupling with mass spectrometry for isotopic analysis, and applying chemometric or machine learning approaches to trend prediction and failure diagnostics. Advances in plasma torch design and solvent-resistant components will further enhance throughput and reliability.

Conclusion

The Shimadzu ICPE-9820 demonstrates robust performance for quantifying additive, wear and contaminant elements in lubricating oils per ASTM D5185. It delivers high accuracy, precision and sensitivity, while reducing carbon deposition and gas costs. This makes it a practical solution for laboratories conducting routine oil condition monitoring in automotive, marine and industrial applications.

References

1. ASTM International Standard D5185: Standard Test Method for Determination of Additive Elements, Wear Metals, and Contaminants in Used Lubricating Oils and Determination of Selected Elements in Base Oils by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES).
2. The Japan Petroleum Institute Standard JPI-5S-44-2011: Method for Analyzing Fe, Cu, Al, Pb, Cr and Sn Contents in Used Lubricating Oil Using Solvent Dilution—Inductively Coupled Plasma Atomic Emission Spectrometry.