Gas Chromatographs

What is a gas chromatograph?

A gas chromatograph (GC) is an efficient analytical instrument used for separating and analyzing volatile compound mixtures, widely used in various fields such as environmental testing, food safety, chemical analysis, medical testing, forensic science, etc. Gas chromatography is based on the different distribution coefficients of different compounds between the stationary phase and the mobile phase, in order to achieve the separation and quantitative analysis of each component in the sample.

What is the working principle of a gas chromatograph?

The core principle of gas chromatography is that when the sample is injected into the injection port at high temperature, the sample quickly vaporizes and enters the chromatography column with the carrier gas. Within the column, different components have varying strengths of interaction with the stationary phase, resulting in differences in their flow velocity within the column and ultimately being separated sequentially. When the components flow out of the chromatographic column, they are detected by the detector, forming a chromatogram where each peak represents a compound.

What are the main components of a gas chromatograph?

1. Carrier gas system: Common carrier gases include helium, nitrogen, or hydrogen, which are used to carry the sample into the chromatographic column.
2. Injection system: including manual or automatic injection devices to ensure that samples enter the system in a stable and reproducible manner.
3. Column: Packaged Column: The column is filled with fixed phase particles and is commonly used for analyzing large molecules or complex mixtures. Capillary Column: With a smaller inner diameter and higher separation efficiency, it is commonly used for trace component analysis.
4. Column temperature box: controls the column temperature to regulate the separation effect and has a programmed heating function.
5. Detector: Flame ionization detector (FID): Highly sensitive to organic compounds and widely used. Thermal conductivity detector (TCD): a universal detector suitable for gases and inorganic substances. Electron Capture Detector (ECD): Used for detecting halogenated compounds.
6. Data system: Collect, process, record chromatographic signals, output chromatograms and analysis reports.

What are the application areas of gas chromatograph?

1. Environmental monitoring: detecting volatile organic compounds (VOCs), pollutant gases, etc. in the air and water.
2. Food analysis: detecting additives, pesticide residues, aroma substances, etc. in food.
3. Pharmaceutical industry: drug quality control, analysis of drug metabolites in blood.
4. Petrochemical industry: crude oil component analysis, fuel quality control.
5. Forensic medicine: alcohol concentration analysis, toxin screening.