Analysis of Oils

Importance of the Topic

Accurate multi-element analysis of oils is essential for quality control, regulatory compliance and process optimization in the petroleum industry. Tightening limits for contaminants such as sulfur, nickel and vanadium demand sensitive, reliable techniques that minimize sample preparation and maximize throughput.

Objectives and Study Overview

This study evaluates the performance of the Thermo Scientific ARL PERFORM’X 4200 advanced WDXRF spectrometer for the determination of major, minor and trace elements in oil matrices. Key goals include demonstrating detection limits, precision, stability and compliance with industry methods (ASTM D2622, D4927; ISO 20884).

Applied Methodology

Ultrapure Conostan oil standards were prepared at concentrations up to 50 ppm by diluting a 50 ppm stock solution. Samples were introduced directly into liquid cells sealed with 6 µm polypropylene film. Sequential wavelength-dispersive X-ray fluorescence measurements employed element-specific analytical lines, counting times of 100 s per element, and standard sensitivity calibration. Background correction and matrix effects were handled via conventional spectral analysis and optional UniQuant standard-less algorithms.

Instrumentation

• Thermo Scientific ARL PERFORM’X 4200 WDXRF spectrometer (4200 W)
• Five-generation Rh X-ray tube, integrated helium shutter and helium flush for liquid analysis
• Six programmable primary beam filters and four collimators
• Up to nine analyzing crystals and dual detectors (flow proportional counter and scintillation counter)
• Anti-drip filter or full tube shield, sample‐recognition sensor and OXSAS control software under Windows® 7

Key Results and Discussion

Limits of detection (LoD) were sub-ppm for most elements, with LoD below 0.5 ppm for elements from aluminum to molybdenum. Light elements exhibited higher LoDs (e.g., Na 8.45 ppm, Mg 2.21 ppm) due to absorption by polypropylene film. Excellent repeatability and spectral resolution enabled precise quantification across a dynamic range from sub-ppm to 100 %. UniQuant standard-less processing provided reliable results when matrix-matched standards were unavailable.

Benefits and Practical Applications

• Minimal sample preparation—direct measurement of oils without dilution or digestive steps
• High sensitivity and resolution for light and heavy elements in a single run
• Rapid sequential analysis reduces total measurement time while maintaining precision
• Compliance with international petrol industry norms (ASTM, ISO) for regulatory and QA/QC laboratories
• Flexible filters and tube protection enhance instrument uptime and sample safety

Future Trends and Applications

Advances in software integration, automation and real-time data analysis will further streamline XRF workflows. Emerging chemometric tools and standard-less algorithms will expand applicability to complex oil mixtures and waste streams. Portable and benchtop WDXRF systems may offer on-site monitoring for field operations and environmental assessments. Continued improvements in detector technology and low-absorption sample cells will push detection capabilities into sub-ppb regimes.

Conclusion

The ARL PERFORM’X 4200 WDXRF system delivers robust, high-throughput multi-element oil analysis with excellent detection limits and stability. Its flexible configuration, minimal sample preparation and compliance with industry standards make it an ideal choice for central laboratories, QA/QC and research applications in the petrochemical sector.

References

• Thermo Fisher Scientific Application Note AN41654: Analysis of Oils with the ARL PERFORM’X 4200 WDXRF Spectrometer (2011)