Gas Chromatography Mass Spectrometry (GC-MS)

What is Gas chromatography mass spectrometry

Gas Chromatography Mass Spectrometry (GC-MS) is an analytical technique with combines the two powerful techniques of gas chromatography (GC) and mass spectrometry (MS), to analyse the compounds present within complex chemical mixtures.

During this process, the mass spectrometer instrument acts as a detector, identifying and quantifying vaporized compounds that have been separated by gas chromatography (GC). While GC provides information on retention time and peak intensity, mass spectrometry adds an additional layer known as mass data. This mass data is crucial for identifying, quantifying, and understanding the structural and chemical properties of molecules.

The key advantage of GC-MS lies in its ability to deliver rich, multidimensional data, offering both qualitative and quantitative insights. Mass spectrometry can detect compounds at extremely low concentrations, making it the preferred method for regulatory assessments and quality control procedures. Additionally, GC-MS is a powerful tool for impurity analysis, providing detailed molecular characterization at trace levels across various sample types.

What are the processes that occur in a mass spectrometer ? 

Gas Chromatography Mass Spectrometry analysis begins with the sample being vaporized in the injector of a gas chromatograph (GC), where it is transformed into the gas phase and separated into its individual components using a capillary column coated with a stationary phase.

An inert carrier gas, typically helium propels the vaporized compounds through the system. As the compounds travel through the column, they interact with the stationary phase, and each compound moves at a different speed depending on its unique chemical properties. This process leads to their separation before entering the mass spectrometer instrument.

Once introduced into the mass spectrometer, the compounds undergo ionization in the ion source, where neutral molecules eluting from the GC column are converted into ions.

There are two common ionization methods: Electron Ionization (EI) and Chemical Ionization (CI). Electron Ionization is the most commonly used method where the molecules are ionized and fragmented by colliding with high-energy electrons, producing ions with specific masses.

These newly created ions are then separated in the mass analyzer based on their mass-to-charge ratio (m/z). The ions then reach the detector, where their m/z ratio and relative abundance (the quantity of each fragment present in the sample) are measured.

In the mass spectrometer instrument, the ion source, mass analyzer and detector all operate under vacuum conditions.

The mass spectrometer generates a mass spectrum, a graph that displays signal intensity or abundance corresponding to each detected fragment’s m/z ratio. This m/z ratio acts as a unique “fingerprint” for the molecule, aiding in chemical identification.

In Electron Ionization ( 70 eV), the mass spectra obtained can be compared to existing mass spectral libraries, facilitating the identification and quantification of unknown compounds and target analytes during the analysis.

Gas Chromatography Mass Spectrometry Applications:

Environmental Monitoring

GC-MS is extensively used in environmental monitoring to detect and quantify pollutants in air, water, and soil. It is highly effective in identifying volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), pesticide residues, and persistent organic pollutants (POPs).

Food Industry

In the food industry, Gas Chromatography Mass Spectrometry is employed to monitor contaminants in food products. It also analyses the composition of foods and beverages, identifying flavour and aroma compounds that contribute to their sensory profiles. Additionally, it helps assess ingredient quality, detect adulteration, and analyse fatty acid composition, supporting food safety and quality assurance.

Forensics

GC-MS is widely used in forensic investigations to analyse chemical traces and establish potential links to crime scenes. Gas Chromatography Mass Spectrometry is also instrumental in identifying fire accelerants and explosive residues, validating the presence of igniters or accelerants in arson cases.

Toxicology

GC-MS plays a critical role in toxicology by identifying drugs, poisons, and metabolites present in human blood or urine samples. Its high sensitivity provides key scientific evidence in criminal investigations involving substance use or poisoning.

SCION has been performing GC-MS analysis for years.

View some of our application notes utilising GC-MS analysis for a variety of different purposes: 

• Flavour and Aroma Profile of Hops  
• Headspace Assay of Polymers used in the Automotive Industry 
• Determination of Hexanal in Foods 
• Determination of Furan in Coffee 
• Achieving Low-Level Detection of Benzene in Beverages 
• Analysis of Dioxins 
• Multiplexed Pesticide Analysis 

SCION GC-MS

The SCION GC-MS range is specifically engineered to meet the needs of modern, high-throughput analytical laboratories. Offering both precision and efficiency, we offer the SCION 8700 Single Quadrupole (SQ) MS and the 8900 Triple Quadrupole (TQ) MS, both of which are designed to integrate effortlessly with SCION’s gas chromatography (GC) instruments. These systems deliver exceptional performance, reliability, and productivity, making them ideal for laboratories with demanding analytical workflows.

The 8700 Single Quad (SQ) MS is a versatile and robust mass spectrometer that excels in routine applications requiring high sensitivity and reliability. Its ease of use, coupled with its cost-effectiveness, makes it a go-to solution for both targeted and untargeted analyses in industries such as environmental monitoring, food safety, and quality control. The SCION 8700 provides accurate mass filtering and quantification with minimal maintenance, ensuring consistent results even in fast-paced laboratory environments.

The SCION 8900 Triple Quad (TQ) MS, on the other hand, is specially designed for more complex and rigorous analyses. This advanced system offers unparalleled selectivity and sensitivity, in applications where trace-level detection and quantification are critical. With its ability to perform Multiple Reaction Monitoring (MRM), the 8900 TQ-MS is ideal for applications requiring precise quantification of low-abundance compounds in complex matrices, such as pharmaceuticals, forensics, and toxicology. Thanks to its fast MRM scan speed(1,000 MRM/sec), 8900 TQ-MS is also an excellent tool for analyzing more than hundreds of pesticides in a single run.