Fuel Analysis with the Agilent 4500 Series FTIR: Monitoring Refinery Formulation to Ensure the Production of FAME-Free Marine Diesel Fuel

Significance of the Topic

Diesel fuel blending increasingly incorporates biodiesel (FAME) to reduce emissions and reliance on fossil sources. However, certain engines used in marine pleasure craft, aviation, and critical backup systems require FAME-free diesel to avoid material incompatibility and operational failures. Detecting trace biodiesel below 0.1% is essential to meet BS ISO 8217 regulations and refinery specifications, ensuring safe performance and engine longevity.

Objectives and Study Overview

This study presents an application of the Agilent 4500 Series FTIR with proprietary DialPath sample technology and a multivariate Biodiesel Measurement Method. A major UK refinery applied this approach to monitor each batch of marine diesel over a one-month period. Key goals included verifying compliance with BS ISO 8217 (<0.1% FAME), adhering to a stricter refinery action level (0.05% FAME), and demonstrating rapid, accurate field analysis.

Methodology and Instrumentation

The measurement protocol harnesses partial least squares regression and transmission IR concepts to achieve an LOD of 0.025% FAME. Analysis targets the carbonyl absorbance band at 1745 cm⁻¹, which correlates linearly with biodiesel concentration in undiluted diesel samples. The precalibrated multivariate model resides onboard the spectrometer, offering intuitive, one-button operation and visual prompts for ease of use.

Used Instrumentation

• Agilent 4500 Series FTIR spectrometer – compact, portable, battery powered for out-of-lab operation
• Agilent DialPath sample interface – three fixed pathlengths (30, 100, 200 µm) selectable without disassembly, enabling reproducible, spill-free liquid measurement

Main Results and Discussion

Over 30 marine diesel batches were analyzed, with FTIR readings plotted against time. All batches remained below 0.1% FAME, and most were well under the refinery’s 0.05% action threshold. The system also monitored transition periods when road diesel (5–7% FAME) switched to marine grade, detecting intermediate FAME levels reliably. The sub-3-minute turnaround per sample facilitated rapid decision making and batch acceptance.

Benefits and Practical Applications

• Fast, accurate detection of trace biodiesel without sample dilution
• Minimal operator training and one-button workflow
• No consumables or complex cell maintenance required
• Portability for in-field QA/QC at refineries, terminals, or harbors
• Reliable compliance monitoring to safeguard engine performance

Future Trends and Potential Applications

Expanding this FTIR-based approach could support on-site monitoring of alternative fuel blends, real-time quality control in distribution networks, and remote diagnostics linked to cloud platforms. Advances in chemometric methods and miniaturized IR detectors may further enhance sensitivity, broaden analyte scope, and integrate mobile analytics for diverse industrial fluids.

Conclusion

The Agilent 4500 Series FTIR with DialPath technology delivers a robust, user-friendly solution for detecting trace biodiesel in diesel fuel. The method surpasses traditional protocols in speed, accuracy, and operational simplicity, enabling refineries to certify marine diesel compliance and optimize fuel switching processes.

References

• J. Seelenbinder, F. Higgins, Test method for low level detection of biodiesel in diesel using the Agilent 5500t spectrometer, Publication Number 5990-7804EN, May 1, 2011.