GC-MS in Food Test

Gas chromatography- mass spectrometry (GC-MS) is an important analysis method widely used in food monitoring and analysis, and it is one of the main qualitative and quantitative methods for the analysis of complex mixtures.

GC-MS technology usually includes gas chromatography-quadrupole mass spectrometry or magnetic mass spectrometry, gas chromatography-ion trap mass spectrometry (GC-IT-MS), gas chromatography-time-of-flight mass spectrometry (GC-TOF-MS). The scanning mode of quadrupole mass spectrometer is divided into full scan and selective ion scan (SIM). Full scan is to scan and record all the ions within the specified mass range. The obtained mass spectrogram can provide the molecular mass and structure information of the unknown. However, SIM mode only detects selected ions, which can eliminate the interference caused by other components in the sample with strong detection sensitivity and selectivity. It is mainly used for quantitative analysis of substances to be measured with certain properties. TOF-MS provides a faster scan rate and additional sensitivity. Each data point collected by TOF-MS corresponds to a complete mass spectrum. Its ability to detect volatile compounds is stronger than quadrupole mass spectrometry. The IT-MS has a small structure and can store ions for a long time under extremely low pressure. The requirements for the vacuum pump are reduced. The mass spectrometer weight and power consumption are reduced. More convenient for miniaturization design.

Agilent GC-MS Analytical Instrument

GC-MS Analysis Workflow

➢ Sample pretreatment

There are different pretreatment strategies for different samples, mainly including the following types:

• Sample collection
• Samples are dried, sieved and ground, etc. Make the sample finer and more dispersed and easier to dissolve or extract.
• Necessary preventive measures should be taken for substances with biological activity, reactivity, and unstable.
• Solvent exchange, desalination, evaporation, freeze drying, etc.
• Sample extraction
• Sample derivatization

* Gas chromatography uses high-purity (99.9995%) nitrogen, helium and other gases as the mobile phase to separate and analyze compounds that are prone to volatilization without decomposition. If the sample does not meet the above conditions, derivatization may be required. Thereby improving the detection suitability and resolution of metabolites, reducing the tailing effect of polar compounds containing functional groups such as -OH, -COOH, =NH, and enhancing the stability of the substance.

➢ GC-MS analysis: qualitative and quantitative analysis of samples.

➢ Data processing analysis: partial least squares method-discriminant analysis, orthogonal algorithm, artificial neural network and evolution-based computing algorithm.

GC-MS Platform in Alfa Chemistry

1. The resolution of each quadrupole is not lower than the unit mass resolution (unit mass resolution is defined as the lowest resolution that can distinguish two mass spectrum peaks that differ by one mass unit).

2. There are two characteristic precursor ions for the detection of all labeled or unlabeled analytes, and each precursor ion corresponds to a specific fragment product ion.

3. The actual measured ion pair relative ion intensity does not deviate from the theoretical value by more than 15% (corrected to the average value of the standard material) to confirm the stability of the tandem mass spectrum, especially the collision energy and collision gas pressure during the fragmentation of each analyte.

Alfa Chemistry' analytical scientists have extensive experience and knowledge in the application of GC-MS analysis to the food industry. We can provide fast turn-around, clear and concise written reports and customized services to help customers solve your analytical and technical problems. Contact us to discuss more.