A New Test Method for the Determination of Derivatized Chemical Species in Marine Fuel Oil by Multidimensional GC/MS

Significance of the topic

The reliable detection of trace chemical species in marine fuel oil is essential to prevent engine fouling, ensure compliance with ISO 8217 and forthcoming ASTM standards, and protect maritime assets. Derivatized analytes such as fatty acids, fatty acid methyl esters, monoglycerides, bisphenols and dihydroxybenzenes can impact performance and environmental safety. A robust analytical protocol enhances quality control, reduces maintenance costs and supports regulatory requirements.

Objectives and Study Overview

This study aimed to develop and validate a multidimensional GC/MS test method for ISO TC28 SC4 WG6 to quantify derivatized target compounds in bunker fuel oil. Key goals included defining sample preparation, optimizing GC/MS parameters according to ASTM D7845-20, and assessing linearity, precision and matrix tolerance for fatty acids, FAMEs, monoglycerides, bisphenol A, bisphenol F, benzenediols and 4-cumylphenol.

Methodology and Instrumentation

Sample preparation involved weighing ~0.7 g of fuel oil into an autosampler vial, adding an internal standard solution in pyridine (approximately 400 mg/kg stearic acid-d₃₅) and derivatizing with BSTFA + 1 % TMCS for 15 min after vortex mixing. GC/MS analysis used an Agilent 7890 GC coupled to a 5977B MSD. A 1 m Agilent J&W DB-1 precolumn (150 µm × 1.2 µm) preceded a 100 m HP-1 analytical column (250 µm × 0.5 µm) with a Purged Ultimate Union backflush. Injection was splitless (1 µL), oven ramped from 140 °C to 325 °C at 10 °C/min, MS in scan mode (m/z 45–520) at 70 eV.

Main Findings and Discussion

Calibration curves for 29 analytes exhibited excellent linearity (R² ≥ 0.998, except methyl behenate at 0.984) over concentration ranges of 0.003–0.95 mg/kg. Repeatability (RSD) at low, mid and high levels ranged 1.6–7.1 %, meeting stringent precision criteria. No significant matrix interferences were observed in distillate, VLSFO and bunker samples. A spiked bunker oil sample (∼100 mg/kg) yielded clear extracted ion chromatograms with well-resolved peaks, confirming method robustness and backflush efficiency for heavy fractions.

Benefits and Practical Applications

• Comprehensive analyte scope covering fatty acids, esters, monoglycerides and phenolic contaminants.
• Minimal sample volume and solvent use through direct autosampler vial derivatization.
• High precision and sensitivity suitable for QC, compliance and research labs.
• Compatibility with existing ASTM D7845-20 setups, facilitating dual-method workflows on a single GC/MS system.

Future Trends and Opportunities

Advances may include coupling with two-dimensional GC for enhanced resolution of coeluting species, use of alternative derivatization agents to improve environmental footprint, integration of high-resolution MS for confirmation, automated sample prep platforms and AI-driven data analysis to accelerate routine screening of complex marine fuels and related petroleum products.

Conclusion

The presented multidimensional GC/MS method fulfills ISO committee requirements and extends ASTM D7845-20 by quantifying additional derivatized species in marine fuel oil. Its validated performance in linearity, precision and matrix tolerance makes it a robust tool for industry adoption, enabling reliable monitoring of potential contaminants in bunker fuels.

Reference

1. ASTM D7845-20: Standard Test Method for Determination of Chemical Species in Marine Fuel Oil by Multidimensional Gas Chromatography/Mass Spectrometry, ASTM International, 2020.