Why Sulfur in Marine Fuel Demands Accurate Analysis

August 6, 2025

Sulfur in marine fuels contributes to acid rain and particulate emissions, posing serious environmental and human health risks. To combat this, MARPOL Annex VI strictly regulates sulfur content in marine fuels such as bunker oil, pushing shipping operators and regulatory bodies toward precise sulfur quantification.

Enter Horiba’s SLFA Series

Horiba’s SLFA analyzers leverage Energy-Dispersive X-Ray Fluorescence (EDXRF) to detect sulfur in petroleum-based samples with high speed and low detection limits. With a dedicated X-ray tube optimized for sulfur excitation and a fully enclosed, safe design, these analyzers eliminate the need for gas utilities or radiation certification.

How It Works

Pour 4-10 mL of marine oil into a sample cup, seal it with Mylar film and locking ring.
The instrument launches with pre-calibrated curves – just press Start.
Within seconds, live data appears. The software then automatically selects optimal calibration (low or high sulfur), computes the final sulfur concentration, and outputs statistical indicators. Results and data can be exported via USB.

Horiba’s default calibration uses certified reference materials spanning 0‑4% sulfur, minimizing matrix effects automatically and ensuring accuracy across fuel compositions.

Why Choose SLFA for Marine Fuel QC?

Speed and simplicity: Onboard or lab analysis in just minutes.
Regulatory compliance: ASTM D4294 / ISO 8754 / JIS‑equivalent methods supported.
Portable option: SLFA‑60’s small footprint and no gas requirement make it ideal for on‑ship testing.
High throughput: SLFA‑6800 supports autosampling for QC laboratories.
Minimal operator training: Ready-to-run software, curve auto‑selection, USB export.

Key models:

SLFA‑60: Compact and portable – Ideal for onboard testing (vessels, tankers).
SLFA‑6800: Laboratory-grade unit featuring an 8-position autosampler for enhanced throughput and productivity in QC labs.

Performance Metrics

Model	Range	Repeatability	Detection Limit
SLFA‑60	0–10% S	≤ 15 ppm	~20 ppm
SLFA‑6800	0–10% S	≤ 5 ppm	~5 ppm

These analyzers deliver consistent, high-precision results across various marine fuels – even with differing elemental matrices (Ca, Zn, V, Ni) – thanks to sophisticated internal filtering and calibration correction algorithms.

Real-World Comparison with Contract Labs

Testing with real ferry and bunker fuel samples showed close alignment between SLFA readings and contract lab results. For example, samples with ~0.7% sulfur showed agreement within ±0.02–0.03%, demonstrating robustness across sulfur levels ranging from 0.02% up to >3%.

Read the full application note here