Terpene Profile
Instrumentation
The mass spectra we see for α-pinene and β-pinene essentially act as unique fingerprints for these compounds, which are part of a larger group known as terpenes, responsible for the fragrant scents of many plants, including pine. The prominent peaks in these spectra — like the common one at a mass-to-charge ratio (m/z) of 93 — help scientists recognize and confirm the presence of these compounds.
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Much like scanning a barcode to identify a product, scientists can scan these spectral fingerprints to identify and measure the amount of each specific terpene in a sample. This method is not exclusive to pinenes; it's a universal approach used for all terpenes.
The process allows for the detection and quantification of these aromatic compounds, even when they're hidden among numerous other substances in a sample. It's a critical tool for understanding the complex mixtures of fragrances in nature and for ensuring the quality of products that contain terpenes.
Terpene Profiling
Terpene profiling identifies and quantifies the aromatic compounds in cannabis, covering key terpenes like myrcene, limonene, and pinene, providing insights into flavor, aroma, and potential therapeutic effects.
Instrumentation
In GC/MS with liquid injection, a dissolved cannabis sample is injected into a GC, vaporized, and then the terpenes are separated in a column. As they emerge, the MS detects each one by its unique fragmentation pattern, identifying and quantifying them.
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How it works
Gas Chromatography-Mass Spectrometry (GC/MS) with liquid injection is a detailed process that allows for the precise analysis of terpenes in a cannabis sample. Here’s a more in-depth look at how this technique unfolds:
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1. Sample Preparation and Liquid Injection: The process begins with the preparation of the cannabis sample. The sample is typically dissolved in a suitable solvent to create a liquid mixture. Using an autosampler or manually, a precise volume of this liquid solution is injected into the GC system.
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2. Vaporization: Once injected, the sample enters a heated chamber where the solvent evaporates, leaving behind the compounds of interest, like terpenes, in a vaporized state. This step is crucial because GC analysis relies on the separation of gaseous components.
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3. Separation via Gas Chromatography: The vaporized terpenes are carried by an inert carrier gas, often helium or nitrogen, through a coiled column. This column is lined with a stationary phase, a viscous liquid or polymer that interacts differently with each terpene. As a result, terpenes will pass through the column at different rates based on their volatility and interaction with the stationary phase—this is called chromatographic separation.
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4. Detection with Mass Spectrometry: As terpenes exit the GC column, they immediately enter the mass spectrometer. Here, they are bombarded with high-energy electrons, which causes them to ionize—break into charged particles. These ions are then sorted in the mass spectrometer according to their mass-to-charge ratio. Each terpene generates a distinct set of ion fragments, which act as a molecular signature.
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5. Data Analysis and Quantification: The resulting mass spectrum is recorded, showing a series of peaks that correspond to the fragmented ions. By comparing these patterns to known standards or libraries of mass spectra, the specific types of terpenes can be identified. The area under each peak is directly related to the concentration of that terpene in the original sample, allowing for quantification.
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The combination of GC's separation power and MS's detection capabilities makes this method highly effective for identifying and quantifying complex mixtures of terpenes in cannabis products.
It’s a powerful tool that translates the chemical composition of a sample into a format that can be rigorously analyzed, providing detailed insights into the sample’s terpene profile.