Analysis of HC with Complementary Spectroscopic Methods

Significance of the Topic

Comprehensive monitoring of hydrocarbons in fuels and lubricants is essential for ensuring performance, safety, and compliance with environmental and industrial standards. Combining molecular and elemental spectroscopic techniques enables rapid detection of chemical composition, degradation products, contaminants, and wear metals in complex matrices without extensive sample preparation.

Goals and Study Overview

This study outlines a multi-technique spectroscopic approach for hydrocarbon analysis. The objectives are to demonstrate how FTIR, UV-Vis-NIR, Raman fluorescence, energy dispersive X-ray fluorescence, atomic absorption, and inductively coupled plasma methods can be integrated to:

• Quantify fatty acid methyl esters in biodiesel
• Assess degradation and contamination in lubricants
• Measure soot content in engine oils
• Determine additive elements and wear metals in used oils

Methodology and Instrumentation

Molecular spectroscopic methods:

• FTIR with attenuated total reflection using IRSpirit-T and QATR-S accessory for direct liquid sampling
• UV-Vis-NIR and Raman fluorescence to support functional group analysis

Elemental spectroscopic methods:

• Energy dispersive X-ray fluorescence with EDX-7000P for rapid screening of Ti, V, Cr, Ni, Cu, Zn, Ag, Cd, Sn, Sb, Ba, Pb
• ICP-AES (ICPE-9820) and ICP-OES for multi-element quantitation of Al, Ba, B, Ca, Cr, Cu, Fe, Pb, Mg, Mn, Mo, Ni, P, K, Si, Ag, Na, S, Sn, Ti, V, Zn following ASTM standards

Main Results and Discussion

Fatty Acid Methyl Ester Quantitation:
The ATR-FTIR method targets the carbonyl peak at 1747.8 per centimeter to quantify FAME content in biodiesel. The calibration allows detection down to fractions of a percent by volume without sample pretreatment.

Lubricant Degradation Analysis:
By monitoring absorption bands corresponding to O-H, C-O, and C-N bonds, ATR-FTIR differentiated new and used oils. Thermal and oxidative degradation, moisture ingress, and nitration levels were tracked, showing clear spectral changes between fresh and stressed samples.

Soot Measurement in Engine Oil:
ATR-FTIR measurement at 1850 per centimeter provided a linear response for soot concentrations from 0 to 0.2 mass percent. Drop-on-prism sampling produced reproducible spectra suitable for quick contamination assessment.

Elemental Analysis of Waste and Used Oils:
EDX-XRF analysis on 8 milliliter samples yielded rapid screening of wear and additive metals in the 10 to 500 parts per million range. ICP-AES delivered precise quantitation of over twenty elements in used automotive lubricants, with dilution and spike recovery tests confirming accuracy near 100 percent. Use of a closed-chamber design stabilized plasma measurements without oxygen introduction.

Benefits and Practical Applications

• No or minimal sample preparation thanks to ATR-FTIR liquid sampling
• Rapid turnaround for routine quality control and maintenance screening
• High reproducibility and compliance with ASTM methods
• Simultaneous molecular and elemental data for a full chemical profile
• Low argon consumption and oxygen-free plasma for robust ICP-AES analysis

Future Trends and Potential Uses

Integration of miniaturized spectrometers with inline process monitoring will enable real-time quality control in production lines. Combining chemometric modeling with spectroscopic data promises improved predictive diagnostics of lubricant condition. Advances in detector technology may extend detection limits for trace contaminants and support greener methods by reducing gas consumption.

Conclusion

The synergistic use of FTIR, UV-Vis-NIR, Raman fluorescence, X-ray fluorescence, and ICP-AES offers a versatile and efficient toolkit for hydrocarbon analysis. These methods deliver fast, reliable insights into composition, degradation, and contamination, meeting the needs of fuel production, lubricant monitoring, and environmental compliance.

Reference

No explicit literature references were provided in the original text.