Lemongrass Oil on Rxi-5Sil MS (10 m, 0.15 mm ID, 0.15 μm)

Significance of the Topic

Lemongrass oil is a widely used essential oil in flavor, fragrance and pharmaceutical industries. Its complex volatile profile requires rapid and reliable analytical methods for quality control, authentication and process monitoring. Fast gas chromatography–mass spectrometry (GC–MS) offers a high‐throughput approach to separate and identify key terpenes and sesquiterpenes within minutes.

Objectives and Study Overview

This study demonstrates the use of a short Rxi-5Sil MS column (10 m × 0.15 mm ID, 0.15 µm) for ultra‐fast GC–MS profiling of lemongrass oil. The aim was to establish retention times and mass spectral identifications for major constituents, achieving a complete separation in under two minutes.

Used Instrumentation

• Gas chromatograph: Agilent 7890A GC
• Mass spectrometer: Agilent 5975C MSD, quadrupole analyzer
• Column: Rxi-5Sil MS, 10 m × 0.15 mm ID, 0.15 µm film (Restek 43815)
• Inlet liner: Topaz 4.0 mm ID precision inlet liner with wool (Restek 23305)

Methodology

The lemongrass oil was diluted to 1 % in acetone and injected (1 µL) in split mode (100:1) at 250 °C. The oven program ramped from 100 °C to 300 °C at 45 °C/min, then to 320 °C at 30 °C/min with a 5 min hold. Helium carrier gas was maintained at 1.01 mL/min. The MS scanned from m/z 35–500 at 11 scans/s, with transfer line, source and quadrupole temperatures set to 300 °C, 230 °C and 150 °C, respectively.

Main Results and Discussion

Fifteen compounds were baseline‐separated within 1.75 min. Key identified constituents and their retention times include:

• Camphene (0.536 min)
• 5-Hepten-2-one, 6-methyl- (0.551 min)
• β-Ocimene (0.620 min)
• D-Limonene (0.629 min)
• α-Ocimene (0.639 min)
• 4-Nonanone (0.677 min)
• Linalool (0.729 min)
• Z-Citral (1.038 min)
• Geraniol (1.053 min)
• E-Citral (1.111 min)
• Geranyl acetate (1.358 min)
• Caryophyllene (1.514 min)
• α-Caryophyllene (1.556 min)
• α-Amorphene (1.744 min)
• δ-Cadinene (1.751 min)

All peak identities were confirmed using the NIST MS EI spectra library (2005). The short column and rapid temperature program provided sharp peaks and minimal coelution.

Benefits and Practical Applications

Rapid GC–MS profiling reduces analysis time and solvent usage, enabling high daily sample throughput. The method supports quality assurance in essential oil manufacturing, adulteration detection and consumer safety testing.

Future Trends and Applications

• Integration of ultra‐fast GC with time‐of‐flight and high‐resolution MS for enhanced compound confirmation.
• Application of multidimensional GC for trace-level component analysis.
• Adoption of automated data processing and machine learning for spectral interpretation.
• Portable GC–MS systems for on-site authentication and field testing.

Conclusion

The demonstrated fast GC–MS method on a short Rxi-5Sil MS column enables comprehensive profiling of lemongrass oil in under two minutes. This approach offers a robust, sensitive and high-throughput solution for essential oil analysis.

References

• NIST Mass Spectral Library, 2005.