Lavender Oil Analysis Using Agilent J&W DB-WAX Ultra Inert Capillary GC Columns

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Application Note

  • Published: Oct 31, 2016
  • Author: Yun Zhou, Agilent Technologies Ltd, Shanghai
  • Copyright: Agilent Technologies
  • Suppliers: Agilent Technologies
  • Products:
  • Channels: Gas Chromatography

Abstract

Lavender essential oil samples were analyzed using the Agilent J&W DB-Wax Ultra Inert GC column and DB-Wax GC column by GC/FID and GC/MSD. Thirty-six major components were identified. The DB-Wax Ultra Inert GC column showed the same selectivity as the DB-Wax GC column. The DB-Wax Ultra Inert GC column however, generated better peak shape and improved sensitivity for active compounds for complex essential oil analysis.

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Introduction

Lavender essential oil is one of the most versatile essential oils. The oil is an often used addition in hair and skin care products, and is a frequent component in the bouquet of fragrances found in perfumes. Lavender oil is also widely used in aromatherapy, and is thought to have calming, antifl atulence, and anticolic properties [1]. The oil typically contains more than 100 individual components with many of the minor constituents often unidentified or not quantitated. It normally includes high levels of linalool, and linalyl acetate, moderate levels of lavandulyl acetate, terpinen-4-ol, and lavandulol. The amount of 1,8-cineole and camphor often varies between low to moderate [2]. Lavender essential oil of the same variety can vary strongly in composition from supplier to supplier. Its composition depends on the species, location, ground, weather conditions, and the level of expertise of farmers and distillers. Because of its high market value, lavender oils are frequently adulterated to extend the volumetric quantity, or less valuable oils are counterfeited as lavender oil for economic reasons. Characterization of the oils through chemical analysis is a mandatory step in the production chain, carried out both by researchers and quality control labs.

Characterization of these complex oils has been conducted using various gas phase analytical techniques, including GC-FID, GC/MS, GCxGC, and GC/TOF [3]. These analyses are often carried out using two different stationary phase columns, a low-polarity column, and a polar column to acquire more reliable qualitative and quantitative data. Relevant analysis and fingerprinting of lavender oil using nonpolar Agilent J&W DB-1ms Ultra Inert columns has been successfully performed by Lynam and Smith [4]. This study highlights the use of polar, Agilent J&W DB-Wax Ultra Inert columns to resolve the main components in lavender oil samples with both GC/FID and GC/MSD. It also compares the selectivity with the DB-Wax column, a column that has been used extensively in the analysis of essential oils. The retention indexes (RI) on the DB-Wax column have long been established, for example, see the Sadtler Standard Gas Chromatography Retention index Library (Sadtler Research Laboratories, Philadelphia, 1984).

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Experimental

Samples

  • Sample 1: Lavender oil was provided by Shanghai Oasis Flavor & Fragrance Co. Ltd (Shanghai, China).
  • Sample 2: ChromaDex Lavender oil (RG, CAS No. 8000-28-0) was purchased from ANPEL Scientific Instrument Co. Ltd (Shanghai, China). It was noted in its specification that this product line was developed for research and qualitative purposes only.

Each of these samples was diluted 1:20 in ethyl acetate (> 99.9%) from J&K Scientific (Beijing, China) and analyzed using both GC-FID and GC/MS detection.

Instrumentation

Table 1 shows the instruments and conditions, and Table 2 lists the consumable supplies flow path.

Table 1
Table 1. Conditions.

Table 2
Table 2. Flow Path supplies.

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Results and Discussion

The purpose of the tests was to evaluate the performance of Agilent J&W DB-Wax Ultra Inert columns, and compare the selectivity of Agilent J&W DB-Wax Ultra Inert columns with Agilent J&W DB-Wax columns for essential oil analysis.

Lavender oil samples were evaluated first by GC-FID, then identified by GC/MS. Figures 1 and 2 show GC-FID chromatograms for lavender oil samples 1 and 2. Figures 3 and 4 show GC/MS total ion chromatograms for lavender oil samples 1 and 2.

As shown in Figure 1, the J&W DB-Wax Ultra Inert GC column can separate major components well, with excellent peak shape. Figures 2, 3, and 4 demonstrate the identical selectivity between the DB-Wax and DB-Wax UI GC columns.

Figure 1
Figure 1. GC/FID chromatogram of lavender oil sample 1 on an Agilent J&W DB-Wax Ultra Inert, 30 m column.
See Table 1 for chromatographic conditions, and Table 3 for peak identification.

Figure 2.
Figure 2. GC/FID chromatogram of lavender oil sample 2 on an Agilent DB-Wax and an Agilent DB-Wax Ultra Inert GC column. For peak identification, see Table 3.

Figure 3.
Figure 3. GC/MS total ion chromatogram of lavender oil sample 1. Using an Agilent J&W DB-Wax, 30 m × 0.25 mm, 0.25 μm GC column and an Agilent J&W DB-Wax Ultra Inert, 30 m × 0.25 mm, 0.25 μm GC column.

Figure 4.
Figure 4. GC/MS total ion chromatogram of lavender oil sample 2. Using an Agilent J&W DB-Wax (blue) and an Agilent J&W DB-Wax Ultra Inert, 30 m × 0.25 mm, 0.25 μm GC column (red).

Table 3.
Table 3. Peak identification by GC/MS and GC/FID area percentages for lavender oil
samples 1 and 2 using Agilent DB-Wax UI and Agilent DB-Wax columns.

That means virtually no method development or revalidation is needed when upgrading from a DB-Wax to a DB-Wax UI column.

Thirty-six major components in lavender oil samples, from International Standard ISO 3515 [5], were identified, and the area percent was integrated and calculated in this work. These 36 compounds accounted for about 96% of the area observed in the GC-FID chromatograms. Table 3 has a list of identified components, their relative retention times, and FID area percentages. International Standard ISO 3515 specifies certain characteristics of the lavender oils from various origins to facilitate assessment of their quality. The supplier could not provide species or location for sample 2. Lavender for sample 1 was cultivated in Xinjiang, China. The content of key compounds in sample 1 and sample 2 are different, but both of them can meet ISO requirements (Table 3).

DB-Wax and DB-Wax UI GC columns show the same selectivity for lavender oil analysis, and overall similar performance. However, the DB-Wax UI does provide better peak shape in some cases, and some sensitivity improvement because of its improved inertness. Figure 5 shows that some more active compounds such as terpinen-4-ol (peak 26) and α-terpineol (peak 30) exhibit excellent peak shape and better response on the DB-Wax UI GC column. This illustrates the good inertness performance of the column. Although Bornanol and Germacrene D (peak 31) could not be separated well on DB-Wax UI under the testing conditions in Table 1, these two compounds were coeluted on DB-Wax. Better resolution of Bornanol and Germacrene D, and acceptable resolutions of other main compounds could be achieved if the oven temperature program was from 50 °C (5 minutes), 5 °C/min to 250 °C (5 minutes). However, Bornanol and Germacrene D are not the compounds specified for quality evaluation of lavender oil. The testing conditions in Table 1 were used in this application note to get more reliable results.

Every J&W DB-Wax Ultra Inert column is rigorously QC tested with demanding probes to ensure the highest degree of inertness from column-to-column.

Figure 5.
Figure 5. Enlarged section of GC/MS chromatogram of lavender oil sample 2 shown in Figure 4, using an Agilent J&W DB-Wax (blue) and an Agilent J&W DB-Wax Ultra Inert 30 m × 0.25 mm, 0.25 μm GC column (red).

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Conclusions

An Agilent J&W DB-Wax Ultra inert GC column was evaluated by analyzing lavender oil samples using GC/FID and GC/MSD. In comparison with the DB-Wax GC column, the same selectivity was successfully demonstrated. This selectivity means that no additional method development or validation is needed when using a DB-Wax UI GC column to replace an Agilent DB-Wax column. Better peak shape and improved sensitivity for active compounds can be achieved because of the high inertness performance of the DB-Wax UI GC column. Characterization of complex lavender essential oil with the DB-Wax UI GC column, combined with the nonpolar Agilent J&W DB-1ms Ultra Inert column can acquire more reliable qualitative and quantitative data, ensuring product quality.

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References

  1. Hawkins, E. B. MS, BSPharm, RPh; Ehrlich, S. D. NMD. Lavender. Research Review January 2007, Phoenix, AZ. Review provided by VeriMed Healthcare Network.
  2. McGimpsey, J. A.; Porter, N. G. Lavender. A grower’s guide for commercial production, New Zealand Institute for Crop and Food Research Limited, Christchurch, New Zealand, 1999.
  3. Shellie, R.; Mondello, L.; Marriot, P.; Dugo, G. Characterization of Lavender Essential Oils by Using Gas Chromatography-Mass Spectrometry with Correlation of Linear Retention indexes and Comparison with Comprehensive Two-Dimensional Gas Chromatography. J. Chromatog. A 2002, 970, 225–234.
  4. Kenneth Lynam, Doris Smith. Lavender Oil Characterization Using Agilent J&W DB-1ms Ultra Inert Capillary GC Column; Application note, Agilent Technologies, Inc. Publication number 5990-3700EN, 2009.
  5. ISO 3515:2002 - Oil of lavender (Lavandula angustifolia Mill.) Standard, available for download on the International Organization for Standardization website: http://www.iso.org.

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