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GC Headspace Sampler Caution and common fault points

Source:未知 Posted:2015-08-12 23:51 Browse:

Headspace gas chromatography is a fast, easy sample preparation method, the principle is the sample into a sealed container, by heating up the volatile components evaporate from the sample matrix, In the gas-liquid (or gas-solid) two phases balance, direct extraction of the top gas subjected to gas chromatography analysis to test the sample composition and content of volatile components. Using headspace technology can remove the sample before lengthy and cumbersome process, avoid organic solvents cause interference analysis, and reduce the column inlet contamination.
 
Headspace gas chromatography autosampler the following precautions:
1. Since the carrier gas into the headspace while entering the gas chromatograph, so for headspace gas should purify;
2. Vial heating temperature, sample loop temperature, the temperature should be steeled transmission line, transmission line less than equal to the inlet temperature;
3. When the temperature setting is not too high, so as not to undermine the headspace analyzer and shorten life. Non-volatile or less volatile sample should not be measured by headspace method;
4. Because of headspace gas chromatography instrument required and used in combination, it should be noted that headspace gas chromatography instrument parameters and parameters of mutual unity, such as a gas chromatograph vaporization chamber temperature is higher than the temperature of the conveyor belt to facilitate the vaporization of the sample.
 
GC headspace Common Faults and Solutions
1. When Headspace Sampler appears on the display 555 or 000, all without heating thermostat parts, injection procedure does not move, purge key does not respond, you can determine the temperature measuring resistor is open or short, you can contact the manufacturer to request a replacement thermometer Resistance can be;
2. Headspace does not heat up, the corresponding parts of the heater burn or ambient temperature is too low, the air-conditioning temperature to 15 ℃ or contact the manufacturer;
3. Headspace, the chromatograph no peaks (chromatograph operating normally), there are four possible faults:. A headspace sampling needle blockage; b syringe blockage; c headspace syringe outlet. pressure is less than the pressure chromatography stigma;. d headspace valve clogged with spare parts for replacement of needles, or press the purge button, burned with a lighter rubber carbide needle ,, after blowing gas blockage. With the above steps, the first lower head pressure chromatography, then the headspace needle into the column inlet, and then increase the headspace pressure;
4. Color spectrum gas leak out Lianfeng different home-based small or repetitive variation (chromatograph operating normally) can be determined that the headspace sampling system leak, contact the factory overhaul;
5. Injection process abnormal noise, damping ring may be sampling pump solenoid valve line package is damaged or abnormal, should be replaced immediately damping rubber ring;
6. Sampling needle without opening a gas emitted when the purge valve, purge solenoid valve may be leaking, contact the manufacturer must be replaced.