The GC is used to analyse volatile molecules with a high melting point, such as fatty acids in fish oil. In addition, samples submitted to the GC do not need solvents or a “liquid mobile phase”; instead, samples are carried by an inert gas through the system. Hence, if we are testing for solvents, the instrument of choice is the GC-FID/MS; no steps are needed to factor out any solvents used to prepare the sample.
GC-MS is precisely able to identify and determine the quantity of the molecules of interest, whereas GC-FID is only used to determine the quantity of molecules. Like LC-MS/MS, GC-MS is also able to create an electronic signature of a molecule. The complexity of running the test will dictate which instrument will be used.
Identity and purity are critical for essential oils. Our GC-MS validates that our essential oils are authentic and 100% pure. It also screens for over 80 common pesticides.
Oregano exists in a variety of species, each containing an array of volatile oils. GCMS validates every batch, ensuring only Origanum minutiflorum, the revered species of oregano, is present. It then quantifies the precise therapeutic amount of carvacrol present, ensuring our entire family of Wild Oregano C93 products meets the therapeutic content consumers expect.
In a GC system, the vaporized sample is moved with a carrier gas through a specially coated capillary column. The column separates the components before entry into the detector; in our case, either the FID or MS, depending on the application.
GC-FIDs detect the unique fatty acid profiles specific to each of our exotic oils, allowing us to ensure they do not contain any carrier oils or other fillers that dilute quality
We also use the GC-FID system to determine the quantity of common fatty acids and essential oils present in oils such as tamanu, argan, and fish oil.
This is a typical fatty acids chromatogram of an argan oil sample.
PCBs and pesticides are tested for through the GC-MS. As the samples pass through the ionization chamber, they are bombarded with a very high voltage of electricity that results in complete fragmentation (separation) of the individual compounds. The fragments are reconstructed as they move through a vacuum tube as per their mass-to-charge ratio. The given signal is recorded by the computer for analysis.
The compounds are compared with a well-known library from the National Institute of Standards and Technology (NIST) or a certified reference standard material.
The total ion chromatogram below represents a pesticides mixture.
Samples being tested for solvents pass through our headspace GC-FID. The FID incinerates the sample, giving an electrical signal for analysis. We use this setup to detect if there are solvents, such as 1,2-dichloroethane and 1,1,1-trichloroethane—which are known human carcinogens. These contaminants can be present in low-quality herbal extracts.
The chromatogram below represents residual solvent.
Additional info (found in other website labs) Do not plagiarize 🙂 but edit later
What is GC-FID analysis used for?
GC-FID is primarily used in industry and research to characterize mixtures of organic compounds. In pharmaceutical testing, the method can be used to identify residual contaminants, and in the petrochemical industry to identify and quantify different hydrocarbon components in oil and other fuels.
GC-FID can also be used in food testing to determine the fatty acid profile of food. In environmental research, the technique can be employed to identify resin acids in water and contaminants in air samples.
How does GC-FID work?
Initially, the sample is passed through a gas chromatography column. This evaporates volatile compounds and causes the resultant gaseous mixture to be separated into individual components. Once the sample reaches the end of the column, it enters the flame-ionization chamber, where it is mixed with hydrogen and a suitable oxidant. This mixture is then burned with a hydrogen flame, causing any chemical components to become ionized and giving them a positive charge.
Above the flame is a negatively charged collector plate. As the positive ions emerge, they are accelerated towards the collector plate where, upon making contact, they induce an electric current. This current is measured, with the amount of current being related to the number of carbon atoms burned. By logging the data, it is possible to determine which components were present in the original sample, and in what quantities.
Sample requirements and preparation
GC-FID samples are generally prepared by dissolving or mixing the material in a low-boiling-point solvent, such as methanol. This solution is then injected into the chromatograph, which will cause it to vaporize rapidly into the gas phase. Note that solid organic samples can be analyzed this way, provided that they become volatile once dissolved.
GC-FID vs. GC-MS – What are the differences?
Gas chromatography–mass spectrometry (GC-MS) starts the same way as GC-FID, by separating the sample in the gas chro#matograph. However, instead of a flame ionization detector, the sample is then passed through a mass spectrometer, which further separates and measures the ions based on their mass-to-charge ratio.
Typically, GC-MS is most useful when it comes to qualitative analysis, such as identifying unknown compounds and molecules based on their size. GC-FID, on the other hand, provides higher accuracy in quantifying many components.
To achieve a comprehensive set of results, GC-MS and GC-FID are often used in tandem with each other. A good example of this is NIAS testing of food contact materials, where the combined GC-MS/FID method can be used to first identify previously unknown components (with the MS detector) and then quantify them (with FID).
Need an analysis?
Measurlabs offers high-quality GC-FID analyses for different industries and fields of research. Many of these analyses can be ordered online. Check out, for example, this purity assay of organic solvents, which combines GC-FID with Karl Fischer titration to determine the purity of a solvent.
Whenever you order an analysis through our website, our experts will check the specifications you provide to make sure the measurement is suitable for your samples. If you wish to discuss your measurement needs in more detail, feel free to contact us through the form below.
