Analysis of diesel using the 4100 MP-AES

Importance of the topic

Trace elements in diesel fuels can lead to component corrosion and deposit formation under high temperature conditions, necessitating reliable quantification to meet industry standards and ensure engine performance.

Objectives and study overview

This study evaluates the performance of the Agilent 4100 MP AES for determination of magnesium, calcium, sodium and potassium in petro-diesel and biodiesel matrices, demonstrating compliance with ASTM and EN fuel specifications.

Used Instrumentation

• Agilent 4100 Microwave Plasma-Atomic Emission Spectrometer with magnetically coupled nitrogen plasma
• External Gas Control Module for controlled air injection
• OneNeb inert nebulizer with solvent-resistant tubing
• Double-pass glass cyclonic spray chamber

Methodology

Samples were prepared following EN 14538, using matrix-matched calibration standards at 0.5, 1, 5 and 10 ppm in a Shellsol solvent. A diesel sample was spiked at 0.5 ppm to validate accuracy. Instrument settings included auto background correction via MP Expert software to counteract carbon background from the organic matrix.

Main results and discussion

Detection limits (3σ of ten blanks) were 2.7 ppb for Mg and K, 8.2 ppb for Ca and 18.7 ppb for Na. Spike recoveries ranged from 93 to 97 %, confirming accuracy at low ppm levels. Potassium calibration exhibited a correlation coefficient of 0.99991. The nitrogen plasma remained stable under high organic loads, and EGCM air injection effectively prevented carbon buildup.

Benefits and practical applications

• Elimination of flammable gases reduces safety risks
• Lower operating costs compared to flame atomic absorption
• Unattended operation and no need for hollow cathode lamps improve productivity
• High tolerance to organic samples enables routine analysis of fuels and similar matrices

Future trends and opportunities

Future developments may include integration with online process monitoring, expansion to more complex matrices, enhanced automation with AI-driven optimization, and novel nebulization approaches for increased sensitivity and robustness.

Conclusion

The Agilent 4100 MP AES with OneNeb nebulizer and EGCM offers a robust, cost-effective and safe solution for trace elemental analysis in diesel fuels, meeting stringent detection limits and accuracy requirements.

References

1. ASTM D6751-11b Standard Specification for Biodiesel Fuel Blend Stock B100 for Middle Distillate Fuels, ASTM International
2. J Moffett and G Russell, Evaluation of a novel nebulizer using an inductively coupled plasma optical emission spectrometer, Agilent Application Note 5990-8340EN
3. EN 14538:2006 Fat and oil derivatives – Fatty acid methyl ester (FAME) – Determination of Ca, K, Mg and Na content by optical emission spectral analysis with inductively coupled plasma (ICP OES), European Committee for Standardization