Gas chromatograph is an instrument for qualitative and quantitative analysis of multi-component complex mixtures by using chromatographic separation technology and detection technology. Generally, it can be used to analyze organic compounds with thermal stability and boiling point not exceeding 500℃ in soil, such as volatile organic compounds, organochlorine, organophosphorus, polycyclic aromatic hydrocarbons, phthalates and so on.
Basic structure
There are many kinds of gas chromatograph with different functions, but the basic structure is similar. The gas chromatograph is generally composed of gas path system, sampling system, separation system (chromatographic column system), detection and temperature control system and recording system.
1. gas path system
The gas path system includes gas source, purification and drying pipeline and carrier gas flow control and gasification device, which is a closed pipeline system with continuous operation of carrier gas. The system can obtain pure carrier gas with stable flow. Its airtightness, accuracy of flow measurement and stability of carrier gas flow are all important factors affecting the performance of gas chromatograph.
2. Sampling system
According to the state of the sample, different samplers are used. Micro syringes are usually used to inject liquid samples. Gas samples are usually injected by the push-pull six-way valve or the rotary six-way valve provided by the chromatograph. Usually, a solid sample is first dissolved in an appropriate reagent and then injected with a micro syringe.