Quantifiable Testing of Essential Oils for Quality and Purity
Several quantifiable tests exist that allow scientists, producers, suppliers and end users to be able to test their oils to determine quality and help to ascertain if an oil is pure and of the quality sought after for each particular botanical.
Gas Chromatography and Mass Spectrometry (GC-MS)
Testing by means of Gas Chromatography and Mass Spectrometry can help to verify that the constituents contained within an essential oil sample are representative of what that particular essential oil should contain.
Gas Chromatography and Mass Spectrometry are two separate tests that are usually both conducted on an oil specimen to identify constituents contained within it. Mass Spectrometry assists in identification of the specific constituents measured within Gas Chromatography, so typically, both tests are done together.
Gas Chromatography, also known as Gas Liquid Chromatography is abbreviated as GC or sometimes GLC.
Gas Chromatography measures the constituents contained within a particular essential oil sample by plotting each constituent found within the sample onto a graph. To begin, a sample of the oil is placed into the heating chamber of the gas chromatograph machine. The oil sample is then heated to a specific temperature until the constituents vaporize. Each constituent vaporizes at a different rate of time. As each constituent vaporizes, is passes through a detector that measures a) the time it took for the constituent to vaporize and b) the percentage/concentration of the constituent within the particular sample.
The gas chromatograph machine plots a graph of the results. The x-axis identifies the time that passes between the vaporization of each constituent. The y-axis shows the percentage concentrations of each constituent within the oil.
Mass Spectrometry, abbreviated as MS is often used in conjunction with Gas Chromatography as it can aid in determining if a sample contains any adulterants.
Each compound, after passing through the gas chromatograph machine, is fed into the mass spectrometer. The Mass Spectrometer ionizes the compounds, sorts each by their mass-to-charge ratio and then measures their molecular weights. The results are then charted.
This topic consists of several separate related articles. Use the links shown below to navigate through the series.
- Part 1: Introduction
- Part 2: Why Is the Quality/Purity of an Essential Oil Important?
- Part 3: Aren't Most Essential Oils Pure?
- Part 4: Constituents - What do Essential Oils Consist Of?
- Part 5: Quality vs. Purity - Aren't They the Same Thing?
- Part 6: Quantifiable Testing of Essential Oils
- Part 7: GC-MS Test Results - How Can They Be Used?
- Part 8: Organoleptic Testing of Essential Oils
- Part 9: Other Quantifiable Tests for Testing the Quality and Purity of Essential Oils
- Part 10: Essential Oil Quality and Purity Conclusion: Final Questions/Answers