Analysis of biodiesel oil (as per ASTM D6751 & EN 14214) using the Agilent 5100 SVDV ICP-OES

Importance of the Topic

Renewable bio-based diesel fuels require precise control of trace metal content to protect engine performance and meet regulatory standards. Adherence to ASTM D6751 and EN 14214 limits for sodium, potassium, calcium, magnesium, sulfur and phosphorus is critical for quality assurance in biodiesel production.

Objectives and Study Overview

This application note assesses the performance of the Agilent 5100 Synchronous Vertical Dual View ICP-OES for the determination of regulated metal contaminants in B100 and blended biodiesel samples. The study aims to achieve compliance with US and EU specifications while demonstrating analytical robustness, sensitivity and throughput.

Methodology and Instrumentation

The analysis employed an Agilent 5100 SVDV ICP-OES equipped with:

• Glass concentric nebulizer and double-pass cyclonic spray chamber
• Organic sample kit with 1.4 mm injector and solvent-resistant tubing
• Solid-state RF system at 27 MHz for stable plasma
• Agilent SPS 3 autosampler for automated sample handling

Organic samples were prepared in kerosene-based solvent with matched viscosity. Fast Automated Curve-Fitting Technique (FACT) was applied to correct carbon-based spectral interferences on sodium and potassium lines. Instrument parameters included axial viewing, 1.40 kW RF power, 12 L/min plasma flow and 10 s read time.

Key Results and Discussion

• Method Detection Limits (MDLs) for Ca, K, Mg, Na, P and S were well below regulatory thresholds with FACT correcting interferences to improve sensitivity by up to an order of magnitude for Na and K.
• Calibration curves demonstrated excellent linearity (r2 ≥ 0.999) over 0–2 mg/kg range with less than 5 % error at calibration points.
• Spike recoveries at 0.5 ppm in B100 biodiesel were within ±5 %, confirming accuracy in complex organic matrices.
• Measured metal concentrations in a commercial B100 sample complied with both ASTM D6751 and EN 14214 limits.
• Sample throughput reached 45 samples per hour with argon consumption of 27 L per sample, driven by the fast Vista Chip 2 detector and rapid autosampling cycles.

Benefits and Practical Applications

The Agilent 5100 SVDV ICP-OES provides a cost-effective solution for routine biodiesel QC by combining high sensitivity, robust plasma stability and minimized gas usage. Laboratories can achieve regulatory compliance for multiple elements with reduced background interference and streamlined method development.

Future Trends and Opportunities

• Enhanced background correction algorithms to further lower detection limits in challenging matrices.
• Integration of advanced autosamplers and robotic liquid handling for higher throughput and reduced manual intervention.
• Expansion of analyte panels to include trace metals and non-metallic contaminants for comprehensive fuel profiling.
• Real-time in-line monitoring of biodiesel production processes using compact ICP-OES modules.

Conclusion

The Agilent 5100 SVDV ICP-OES meets the stringent requirements for biodiesel analysis under ASTM D6751 and EN 14214, delivering reliable quantitation of critical metal contaminants with superior sensitivity, rapid analysis and efficient operation. This method supports quality assurance in biodiesel production and paves the way for future automation and enhanced analytical capability.

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