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Food, Flavors, & Fragrances Article

80% Faster GC/MS Analysis of Essential Oils

Using a 10m x 0.10mm ID Rtx®-5 GC Column

by Novalina Lingga, Ph.D., Application Chemist, Shimadzu Asia Pacific, Singapore and
Eberhardt Kuhn, Ph.D., International Marketing Specialist, Restek Corp.
  • 5x greater sample throughput.
  • Sharply reduced cost per analysis.
  • Resolution and elution orders are not changed.

Essential oils are key components of perfumes, soaps, and other cosmetic products, and they find extensive use in aromatherapy. Because they have high market value, essential oils are subject to adulteration with less expensive impurities. It is, therefore, important to have reliable analytical methods to determine the purity of these materials.

Typical analysis times for these complex samples, using a 30m x 0.25mm x 0.25µm df Rtx®-5SilMS column and “conventional” GC/MS conditions, are 18 minutes for bergamot oil and 30 minutes for patchouli oil. Figure 1 shows these analyses optimized for speed, using a 10m x 0.10mm x 0.10µm df Rtx®-5 column. Analysis times were reduced to approximately 3.5 minutes for bergamot oil and 5.5 minutes for patchouli oil. This 80% reduction in analysis time increases sample throughput by a factor of 5, without sacrificing resolution or accuracy!

Relative to conventional analyses, resolution in these fast analyses is essentially unchanged for bergamot oil, and actually is slightly better for patchouli oil. Because the phase ratio (β) was kept constant at 250, the elution order of the oil components is identical for both fast and conventional analyses, allowing easy peak identification and comparison.

These results demonstrate the potential for greatly increased throughput for essential oils by using a shorter, smaller diameter column. The cost savings make this a desirable improved method for any laboratory.

Figure 1  Analyses of essential oils optimized for speed, using a 10m x 0.10mm x 0.10µm df Rtx®-5 column.

Bergamot Oil

  1. α-pinene
  2. sabinene
  3. ß-pinene
  4. ß-myrcene
  5. p-cymene
  6. D-limonene
  7. γ-terpinene
  8. linalol
  9. linalyl acetate (bergamol)



Patchouli Oil

  1. ß-patchoulene
  2. ß-elemene
  3. caryophyllene
  4. α-guaiene
  5. seychellene
  6. α-patchoulene
  7. guaiene
  8. δ-guaiene
  9. selinene
  10. patchouli alcohol

GC_FF00848, GC_FF00849

Column:

Rtx®-5SilMS, 30m x 0.25mm ID, 0.25µm (cat. # 12723)

Sample:

bergamot oil, 5% in acetone, 1µL injection
or patchouli oil, 5% in acetone, 1µL injection

Instrument:

Shimadzu GCMS-QP2010

Injector:

split/splitless, 280°C

Injection mode:

split, split ratio = 100:1

Carrier gas:

helium

Flow control mode:

constant linear velocity (36.0cm/sec)

Column inlet pressure:

46.7kPa @ 40°C

Oven:

40°C (0.5 min) — 5°C/min. — 300°C

Detector:

Shimadzu QP 2010 MSD (Bergamot Oil chromatogram only)

Interface:

direct, 280°C

Ionization:

electron impact

Mass range:

40-500 amu

Chromatograms courtesy of Dr. Novalina Lingga, Shimadzu Asia Pacific, Singapore