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Gas chromatograph


Gas chromatograph
  • Introduction
  • Application
  • Literature
  • Maintenance

Gas chromatograph consists of a gas circuit system, injection system, separation system, detection and temperature control system, and recording system.

The gas circuit system of the gas chromatograph includes a gas source, purification and drying tube, and a carrier gas flow control device. It is a closed pipeline system where the carrier gas runs continuously. Through the gas chromatograph's gas circuit system, a pure and stable carrier gas with a consistent flow rate is obtained. The air tightness of the gas chromatograph's gas circuit system, the accuracy of flow rate monitoring, and the stability of the carrier gas flow rate are all important factors affecting the performance of the gas chromatograph.

The injection system of the gas chromatograph mainly includes a sampler and a vaporizing chamber.

The separation system of the gas chromatograph is the core part of the gas chromatograph, which separates the various components in the sample to be tested. The separation system consists of a column oven, chromatographic column, and temperature control components.

The detection system of the gas chromatograph converts the separated components in the chromatographic column into electrical signals according to their concentration changes. After amplification, the electrical signals are transmitted to the recorder, which plots the chromatographic effluent curve.

In the gas chromatograph, temperature control is extremely important as it directly affects the separation efficiency of the chromatographic column, the sensitivity, and stability of the detector. The main targets of the temperature control system are the vaporization chamber, chromatographic column, and detector.

The recording system of the gas chromatograph is mainly used to record the detection signals of the detector and perform quantitative data processing and recording. Some gas chromatographs are also equipped with electronic computers, which can automatically measure the area of chromatographic peaks, provide accurate data for quantitative analysis, and automatically reprocess and analyze the chromatographic analysis data.

Parameters are as follows:

1. 8-program temperature ramp column oven;

2. 6 temperature control zones (including column oven temperature control);

3. Various program functions (memory, self-diagnosis, time program, etc.);

4. Thermal conductivity detector (TCD)

The TCD has an automatic air break protection function;

Double-column balance mode, suitable for packed column analysis (requires the simultaneous selection of 2 packed column injectors);

Maximum operating temperature: 400°C;

Absolute temperature accuracy: ±0.5% of the set temperature;

Sensitivity S value: ≥2500 mV·mL/mg (n-hexane);

Sensitivity S value: ≥8000 mV·mL/mg (n-hexane) (with amplification);

Noise level: ≤20 μV;

Drift: ≤100 μV/15 min;

Dynamic range: ≥106

5. Flame ionization detector (FID)

Can be controlled by the host or workstation for automatic ignition;

Suitable for packed column/capillary column analysis;

Maximum operating temperature: 400°C;

Minimum detectable limit: ≤5×10-12 g/s (n-hexane);

Baseline noise: ≤2×10-13 A;

Baseline drift: ≤5×10-13 A (30 min)

Stable after 150 min of startup

6. Remote control chromatography workstation;

7. Sampler options:

(1) Packed column injector;

(2) Capillary inlet;

8. Split-type nickel conversion furnace;

9. Imported switching valve for gas path switching.

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