Analysis of Mineral Oils Utilising Temperature Programmed Large Volume Injection

Importance of the Topic

The determination of mineral oil hydrocarbons addresses critical needs in environmental analysis, food safety testing, and industrial quality control. Regulatory frameworks such as DIN-EN-ISO 9377 demand sensitive, reliable methods to detect low-level hydrocarbon contamination in water.

Objectives and Overview

This application note introduces a simplified workflow using a large volume injection technique combined with a programmable temperature vaporizer. The goal is to reduce sample preparation steps, increase throughput, and ensure compliance with established Hydrocarbon Index measurement criteria for concentrations above 0.1 mg/L.

Methodology

Sample preparation involves spiking water extracts into hexane to create calibration standards (0.2–1.0 mg/mL) and a blank. A reference mixture of alkanes from RIVM serves as a quality control. Chromatographic separation uses a temperature gradient: initial hold at 35 °C, ramp to 150 °C, then to 250 °C and finally 350 °C. Solvent venting is achieved by maintaining an open split for 0.17 min at the solvent boiling point, then closing the vent and ramping the injector to transfer analytes onto the column.

Applied Instrumentation

• SCION 456 Gas Chromatograph
• Programmable Temperature Vaporizer injector (PTV)
• SCION Mineral Oil Liner
• Mineral oil capillary column (15 m × 0.32 mm × 0.15 µm)
• Flame Ionization Detector at 350 °C

Main Results and Discussion

System suitability tests based on C10/C20 and C40/C20 peak ratios (acceptable range 0.8–1.2) showed excellent repeatability over 20 injections with RSD below 1%. Calibration chromatograms exhibited clear separation of alkanes, and solvent venting minimized column overload. Analysis of the RIVM reference sample (n=8) yielded an average hydrocarbon ratio of 1.55 with RSD 1.11%, demonstrating robustness and compliance well within the ISO threshold of 14.1%.

Benefits and Practical Applications

By integrating large volume injection with a PTV device, this method achieves high analyte recovery and minimal discrimination without extensive concentration steps. It significantly increases laboratory throughput, reduces solvent usage, and meets DIN-EN-ISO 9377 requirements, making it suitable for routine environmental and food industry testing.

Future Trends and Potential Uses

Emerging developments may include coupling with mass spectrometric detection for enhanced selectivity, further automation of sample introduction, miniaturized PTV designs, and adaptation to multi-residue screening in complex matrices. Integration with online extraction systems can expand applications in real-time monitoring.

Conclusion

The optimized configuration of the SCION 456 GC with PTV large volume injection, specialized liner, and mineral oil column delivers reliable, high-throughput analysis of mineral oil hydrocarbons. Repeatability and recovery performance align with stringent ISO standards, supporting its adoption for environmental and industrial quality control.