Full-automatic headspace samplerIt is a convenient and quick sample pretreatment method in gas chromatography. Its principle is to place the sample to be tested in a closed container, and then heat up to make the volatile components volatilize from the sample matrix. After the gas-liquid (or gas-solid) two phases reach equilibrium, the top gas is directly extracted for chromatographic analysis to check the composition and content of volatile components in the sample. Headspace sampling technology can avoid lengthy and cumbersome sample pretreatment process, avoid the interference of organic solvents on the analysis, reduce the pollution of chromatographic columns and injection ports, and the instrument can be connected with various gas chromatographs at home and abroad.

At present, the analysis methods of automatic headspace sampler include manual method, closed needle sampling method, balanced pressure system and loop pressure system. There are five dynamic compensation types for static sampling method. However, when similar problems occur in headspace sampler, how to determine the cause of specific failure more quickly and accurately? This requires our operators to have a clear idea and know the processing sequence and skills:

1. Whether the failure time and operating conditions of the instrument are the same as when the instrument is normal (whether Modify the parameters, replace the septum, etc.), if they are consistent, you can eliminate the blockage of the transmission injection needle. At this time, you can first judge whether the valve cycle setting time is correct;

2. If the septum of the injection port has been replaced, focus on confirming whether the injection needle is blocked;

3. If the GC capillary column or operating flow has been replaced, please confirm with the user whether the carrier gas pressure adjustment is appropriate;

4. If the operating conditions are the same as before, but there is no peak, directly inject GC to confirm whether GC is normal; If the GC is normal but no peak is generated in the headspace, the headspace enters the manual test mode to confirm whether the solenoid valve and the six-way valve work normally;

5. If the manual mode is normal, check whether it is blocked through sample preparation: connect the water outlet with the water container. No bubbles or bubbles are generated slowly during sample preparation, indicating blockage. It is necessary to confirm whether the sampling needle, quantitative ring, six-way valve, drain valve, etc. are blocked in turn.