Analysis of HC with Complementary Spectroscopic Methods

Importance of the Topic

Hydrocarbon analysis underpins quality control in fuels, lubricants and related petrochemical products. Complementary spectroscopic techniques enable rapid molecular and elemental profiling, supporting engine performance optimization, regulatory compliance and environmental monitoring.

Objective and Overview of the Study

The work presents a combined analytical approach, integrating molecular infrared spectroscopy with elemental methods (EDX, ICP-AES) to quantify fatty acid methyl esters in biodiesel, assess lubricant degradation and measure trace metals in oil matrices.

Methodology

• ATR-FTIR for molecular profiling of FAME, water content, oxidation and nitration products, and soot in engine oils.
• Energy-dispersive X-ray fluorescence (ED-XRF) for rapid quantitation of wear metals and additive elements in lubricants.
• Inductively coupled plasma-atomic emission spectrometry (ICP-AES) for multi-element analysis of 22 additives, wear metals and contaminants following ASTM D5185.

Used Instrumentation

• IRSpirit FTIR with QATR-S and Pearl Liquid ATR accessory for high-accuracy ATR measurements.
• EDX-7000P compact ED-XRF system with SDD detector and primary filters for elemental screening.
• ICPE-9820 ICP-AES for stable dissolved element detection under low-oxygen, low-argon conditions.

Main Results and Discussion

• ATR-FTIR enabled quantitation of FAME down to 0.6 vol% via the carbonyl peak at 1 747.8 cm⁻¹ and detection of water (O–H), oxidation (C–O) and nitration (C–N) in used lubricants without sample pretreatment.
• Soot in engine oil was measured at 1 850 cm⁻¹, with calibration curves constructed for 0–0.2 mass% content.
• ED-XRF delivered linear responses for Ti, V, Cr, Ni, Cu, Zn, Ag, Cd, Sn, Sb, Ba and Pb across 10–500 ppm levels in waste oil with detection limits suitable for routine monitoring.
• ICP-AES analysis achieved recoveries near 100 % in spike-and-recovery tests for both high and low concentration elements, demonstrating stable performance without oxygen introduction.

Benefits and Practical Applications

• Minimal or no sample pretreatment accelerates workflow and reduces chemical consumption.
• ATR simplifies cleaning and ensures reproducible optical path lengths compliant with ASTM E2412.
• Compact instrumentation footprint and low gas usage support laboratory efficiency.
• Combined molecular and elemental data provide comprehensive quality assessment for biofuels and lubricants.

Future Trends and Potential Applications

Advances are expected in portable ATR-FTIR and handheld ED-XRF devices for field analysis, as well as integration with automated sampling and data-driven spectral interpretation. Development of greener plasma sources and miniaturized ICP systems will further extend on-site elemental monitoring capabilities.

Conclusion

The complementary use of ATR-FTIR, ED-XRF and ICP-AES constitutes a robust platform for rapid, accurate hydrocarbon and additive analysis in fuels and lubricants. This combined strategy meets industry standards, streamlines laboratory operations and supports informed decision-making in quality control and research.