Chlorine analysis in fuel oils

Significance of the topic

Chlorine levels in fuel oils directly impact refinery equipment integrity, catalyst performance, and compliance with environmental regulations. Accurate monitoring helps prevent corrosion, catalyst poisoning, and unplanned downtime.

Study objectives and overview

This application note investigates the performance of the Thermo Scientific ARL PERFORM’X 4200 W X-ray fluorescence spectrometer for rapid determination of chlorine in fuel oil. The main objectives are:

• Establish a robust linear calibration for chlorine across relevant concentration ranges.
• Evaluate precision, accuracy, limit of detection, and throughput.
• Demonstrate minimal sample preparation and automated safety features.

Methodology and instrumentation

Certified fuel oil standards with known chlorine content were measured using the ARL PERFORM’X sequential XRF system. Key instrument features include:

• 5GN+ Rh X-ray tube with 50 μm Be window and low-current filament for long-term stability.
• Six primary beam filters, four collimators, nine possible crystals, and two detectors.
• Helium purge and shutter for spectral chamber protection under liquid analysis.
• LoadSafe design with liquid cassette recognition and over-exposure safety.

Calibration was performed by plotting measured intensities against certified concentrations, using a 60-second count time and background correction.

Main results and discussion

The linear regression yielded R² = 0.999964, a standard estimate of error (SEE) of 1.03 ppm, and a limit of detection (LoD) of 0.54 ppm for chlorine. Reproducibility tests across three sample cells produced an average chlorine content of 18.3 ppm with a standard deviation of 0.21 ppm. These results confirm excellent precision and accuracy. Built-in safety features ensured stable operation and protected the instrument from sample-related damage.

Benefits and practical applications

The ARL PERFORM’X XRF method offers several advantages for routine fuel oil analysis:

• Direct measurement of petroleum samples without dilution.
• Fast analysis with 60-second counting cycles.
• High sensitivity and low detection limits for trace chlorine.
• Automated sample handling safeguards and liquid cell protection.
• Small-spot and elemental mapping capabilities for contamination screening.

Future trends and potential applications

Advances in data processing software and machine learning could further improve calibration accuracy and real-time monitoring. Expanding XRF applications to simultaneous analysis of other halogens and trace metals may enhance comprehensive fuel quality assessment.

Conclusion

The Thermo Scientific ARL PERFORM’X 4200 W XRF spectrometer provides a rapid, reliable, and user-friendly approach for chlorine determination in fuel oils. Its high throughput, minimal sample preparation, and robust safety features make it ideal for petrochemical quality control and environmental compliance.