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

Marine engines, particularly those on pleasure crafts and in critical backup generators, can malfunction when exposed even to trace amounts of fatty acid methyl esters (FAME). Ensuring the absence of biodiesel in specific diesel formulations is vital for engine reliability, material compatibility, and regulatory compliance in marine and other sensitive applications.

Objectives and Study Overview

This application demonstrates the use of the Agilent 4500 Series FTIR spectrometer with DialPath technology and a dedicated biodiesel measurement method. The goal is to verify that marine diesel fuel meets BS ISO 8217 requirements (<0.1% FAME) and an internal refinery specification (<0.05% FAME), while providing rapid quality control during fuel formulation and switchover operations.

Methodology

A drop of undiluted diesel sample is placed between two infrared-transparent windows in the DialPath interface, creating a reproducible fixed pathlength. The FTIR measures the carbonyl absorbance band at 1745 cm-1, directly proportional to FAME concentration. A pre-calibrated multivariate algorithm, stored on-board, analyzes spectra in the 1680-1800 cm-1 region. This method achieves a detection limit of 0.025% FAME and eliminates dilution steps and related errors.

Used Instrumentation

• Agilent 4500 Series FTIR spectrometer
• DialPath sample interface with selectable pathlengths from 30 to 200 um
• On-board software with one-button biodiesel quantification method

Main Results and Discussion

Over a one-month period, a UK refinery analyzed each marine diesel batch. All samples complied with the regulatory limit of 0.1% FAME, with some approaching the tighter 0.05% internal threshold. The method also monitored intermediate FAME levels during transition from road diesel (5-7% FAME) to marine diesel, providing actionable data for optimizing switchover timing and preventing cross-contamination.

Benefits and Practical Applications

• Rapid turnaround under 3 minutes per sample including cleaning
• High sensitivity with detection down to 0.025% FAME
• Portability: battery-powered, suitable for field or laboratory use
• Ease of use: minimal training (<30 minutes) and no consumables
• Robust analysis of viscous, undiluted samples

Future Trends and Opportunities

Integration of portable FTIR with real-time data networks and automated quality control workflows can expand on-site fuel monitoring. Advances in multivariate algorithms and compact optics will enhance trace contaminant detection. The approach can be adapted for other fuel types and regulatory standards, supporting broader refinery optimization and compliance strategies.

Conclusion

The Agilent 4500 Series FTIR with DialPath provides a fast, accurate, and user-friendly solution for ensuring FAME-free marine diesel. Its portability and minimal maintenance requirements allow refineries and fuel terminals to maintain strict quality standards anywhere, improving engine safety and regulatory compliance.

Reference

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