Gas chromatography mass spectrometry analysis, or GC/MS analysis, is one of the most commonly used and requested analytical techniques. It is used in quality assurance and product testing procedures in a wide variety of industries. Here is what you should know about GC/MS: How it works, what it’s used for, and how it might benefit your business.
What is gas chromatography mass spectrometry analysis?
Gas chromatography mass spectrometry analysis is a material identification and analysis technique that separates, identifies, and quantifies the individual components of a sample, including potentially unwanted components like contaminants and trace elements.
GC/MS can be used to analyze a wide variety of samples quickly and accurately, regardless of whether these samples are in solid, liquid, or gaseous forms. Unlike many other forms of testing, such as FTIR oil testing, GC/MS is also 100% accurate when performed by professionals and can identify not only the category of substances in a sample, but also each of the specific substances themselves and their quantity within the sample.
How does gas chromatography mass spectrometry work?
GC/MS essentially combines the processes of two different types of analysis: gas chromatography and mass spectroscopy.
At the beginning of the testing process, the sample is injected into the port of an instrument called a gas chromatograph (or GC). Within the GC, the sample is heated until its components volatilize into a gaseous sample vapor.
When the components are vaporized, the chromatograph introduces an inert gas into the port containing the vapor. This gas propels the vapor into a hollow, coiled tube hung in the temperature-controlled oven of the GC.
The inside of the GC column is coated with a porous, solid substance called a “stationary phase,”made of aluminum and silica gel. The different chemical compounds within the vapor pass through the stationary phase at different speeds and therefore separate. Smaller and more volatile compounds travel through the stationary phase faster than longer compounds.
The GC instrument measures how long each separated compound takes to make its way through the column completely, recording this measurement as that particular component’s “retention time.”
After passing through the column and separating, each compound flows directly into the Mass Spectrometer, or MS, and reconvenes as the sample vapor. The MS chamber where the vapor flows contains a large volume of reagent gas, which the vapor interacts with to trigger chemical ionization. During this process, the vapor is broken down into positively-charged ions.
As these ions are created, they are attracted to an electromagnetic field within the MS device’s ion trap. This ion trap only allows a pre-selected range of ion masses to pass through it. As each molecular ion passes through the field, a detector instrument counts them. The MS system uses this data to produce a “mass spectrum” based on the distribution of ions of different sizes flowing out of the trap at different times.
Finally, the GC/MS instrument checks both the mass spectrum produced by the MS and the retention time of each compound measured by the GC against a reference library of over 275,000 mass spectra, each of which responds to both tests in different ways. By cross-checking the data generated by the test, testers can determine and quantify the nature of these compounds with a high degree of accuracy.
What is GC/MS used for?
Gas chromatography with mass spectrometry has a broad array of applications, including:
- Identification and quantification of unknown samples
- Identification of unknown compounds, such as contaminants, within a sample
- Analysis of an environment in which a sample is found and/or kept
- Separation, identification, and quantification of individual components of a sample
- Identification of components or combinations of compounds producing particular effects (such as an odor or flavor) within a sample
- Testing for residual solvents in a sample such as a pharmaceutical product
- Analysis of monomers used in polymers and plastics
In addition, “headspace” GC/MS analysis, which is a type of GC/MS focused on analyzing volatile and semivolatile organic compounds specifically, is effective for analyzing solvents and additives in otherwise difficult to separate volatile samples.
Here are a few examples of how Innovatech has used GC/MS:
A food service vendor was considering switching to a new vegetable oil for their product, but needed to know if making the switch would negatively impact product quality. To determine the possible effects, they needed to compare the properties of the new vegetable oil to their previous oil.
Using GC/MS, Innovatech found that the original oil contained four different types of acid that the new oil did not. Interestingly, this led to two conclusions: using the new oil could affect the food preparation process or the food itself — but, because the original oil included a saturated fatty acid called palmitic acid, the new oil could be considered a healthier alternative.
A pharmaceutical company needed to find the exact amount of a residual methyl methacrylate monomer in their product, in order to determine how the quantity of this monomer would affect various aspects of the product’s performance.
Using headspace GC/MS, Innovatech measured the concentration of the residual monomer by comparing the quantity within the product to standard concentrations of methyl methacrylate and creating a curve depicting both. This allowed the company to understand how much more of this monomer their product contained than the standard distribution, which helped them take next steps in evaluating their production process.
A pharmaceutical manufacturer needed to know if the ethanol they used during their manufacturing process was making its way into the finished product.
Innovatech used static headspace GC/MS to extract, separate, identify, and quantify each compound within a sample of the manufacturer’s product. In doing so, we were able to confirm that ethanol was indeed seeping into the product during the manufacturing process, giving the manufacturer the information they needed to change that process and improve the integrity of their product.
Which industries commonly use gas chromatography mass spectrometry?
The broad applications of GC/MS make it one of the most-applied forms of material identification and analysis used in manufacturing today. Industries that most commonly use GC/MS include:
- General manufacturing
- Food and drink
- Epoxies and other adhesives
How can I tell if a GC/MS test is right for my needs?
If you are concerned about how unknown substances may be affecting your product or you want to know which specific substances may be producing observed effects, GC/MS is likely a practical option for you.
How can I get a GC/MS test?
If you would like to have your product GC/MS tested for any reason, the professionals at Innovatech are ready to help. Get in touch now, and we’ll determine the best test for your needs and carry it out with professional expertise.