WCPS: Multi-element analysis of petroleum crude oils using an Agilent 7900 ICP-MS

Importance of the Topic

In petroleum refining, detection and quantification of elements such as nickel, vanadium, arsenic and selenium are essential for assessing crude oil quality and refining performance. Ultra-trace elemental analysis helps prevent catalyst poisoning and meet regulatory standards.

Objectives and Study Overview

The study aimed to develop a rapid, robust multi-element assay for crude oils using direct dilution in o-xylene coupled with Agilent 7900 ICP-MS, suitable for routine high-throughput analysis in refinery labs.

Methodology and Instrumentation

Samples comprising 18 crude oil types were diluted 1:10 to 1:600 in o-xylene, shaken for 30 minutes and introduced directly into the ICP-MS. Calibration standards covered 23 elements from 1 to 1000 μg/kg. The method employed peristaltic sample uptake, ORS4 collision/reaction cell in helium and hydrogen modes, and a Peltier-cooled Scott spray chamber for stable aerosol generation.

Instrumentation Used

• Agilent 7900 ICP-MS with ORS4 collision/reaction cell
• Concentric glass nebulizer (0.89 mm id)
• Quartz torch with 1.0 mm injector and platinum sampling/skimmer cones
• Peltier-cooled double-pass spray chamber

Main Results and Discussion

Calibration curves for Ni, V, As and Se exhibited correlation coefficients above 0.998. Instrument detection limits ranged from 0.009 ppb (As) to 1.743 ppb (Na). Recovery tests on NIST SRM 1634c showed Ni and V within ±10% of certified values; As and Se recoveries stayed within +10% over 147 measurements across 12 months, demonstrating excellent long-term reproducibility. Quantitative analysis of crude samples revealed vanadium concentrations from 0.07 to 301 ppm and nickel up to 67.8 ppm.

Benefits and Practical Applications

This direct-dilution ICP-MS method offers significantly lower detection limits compared to ICP-OES, simplified sample preparation and high throughput, enabling efficient quality control, feedstock evaluation and compliance monitoring in petroleum operations.

Future Trends and Opportunities

Emerging demands for stricter fuel specifications and regulatory monitoring will drive adoption of ICP-MS protocols in standardized methods. Future developments may include automated dilution systems, expanded collision/reaction gas options for complex matrices, and integration with speciation or molecular techniques.

Conclusion

The Agilent 7900 ICP-MS method provides a sensitive, reproducible and streamlined approach for routine multi-element analysis of crude oils, supporting industry needs for rapid decision-making and regulatory compliance.

References

• [1] www.astm.org