Determination of aromatic hydrocarbon types according to DIN EN 12916:2016

Determination of Aromatic Hydrocarbon Types According to DIN EN 12916:2016

Importance of the Topic

The presence and distribution of monoaromatic, diaromatic and polyaromatic hydrocarbons in middle distillates is a critical factor in assessing diesel fuel quality. These compounds influence combustion characteristics, exhaust emissions and subsequently impact environmental pollution and human health. Regulatory standards such as DIN EN 12916:2016 provide a framework to ensure safe and compliant fuel usage.

Study Objectives and Overview

This study aimed to adapt and validate a normal phase high performance liquid chromatography method with refractive index detection for the quantification of aromatic hydrocarbon types in diesel and diesel blends. The method follows the specifications of DIN EN 12916:2016 and aligns with related calibration standards used in IP391(2000) and ASTM D6591, with minor adjustments to instrument settings.

Methodology and Instrumentation

An AZURA analytical HPLC system was employed under isocratic normal phase conditions. Key parameters included

• Mobile phase: n-heptane
• Flow rate: 1.2 mL/min
• Column: Nucleodur 100-5 NH2, 250 x 4 mm ID
• Column temperature: 25 °C
• Injection volume: 10 µL (full loop mode)
• Detector: AZURA RID refractive index at 20 Hz data rate and 0.05 s time constant

A system suitability test was performed using a multicomponent standard to verify separation efficiency and reproducibility prior to sample analysis.

Main Results and Discussion

System suitability criteria defined in the standard were met. Calibration was carried out at four concentration levels using a mixture of 1,2-dimethylbenzene, fluorene and phenanthrene. Chromatograms demonstrated baseline resolution of monoaromatic, diaromatic and tri+ aromatic groups. Quantification of real samples is achieved by correlating peak retention windows to the group definitions and applying the calibration curves.

Benefits and Practical Applications

This validated method enables accurate monitoring of aromatic hydrocarbon content in diesel fuels, supporting quality control in fuel production, compliance with environmental regulations and risk assessment for public health.

Future Trends and Potential Uses

Innovations may include coupling to mass spectrometry for enhanced selectivity, development of shorter or more environmentally friendly analytical columns, automation of sample processing and expansion to complex biofuel blends with higher renewable content.

Conclusion

The described HPLC-RI method offers a robust and reproducible approach for the determination of aromatic hydrocarbon types in middle distillates according to DIN EN 12916:2016.

Reference

1. ASTM D6591, Standard Test Method for Determination of Aromatic Hydrocarbon Types in Middle Distillates by HPLC
2. DIN EN 12916:2016, Petroleum products – Determination of aromatic hydrocarbon types in middle distillates – HPLC method with refractive index detection