The purge trap immerses helium/nitrogen as a purge in the sample solution; under continuous airflow purge, the volatile components in the sample escape with the purge and are concentrated by the collection device with adsorbent.

Helium was used as a sample solution for blowing gas and bubbles. Under a continuous gas flow purge, the volatile components of the sample escape with helium and are concentrated by a collection device equipped with an adsorbent. After a certain purge time, all or a certain amount of the measured component enters the collector. At this time, close the blow, switch the valve to connect the collector to the open path of the GC, quickly heat the collection sample group to decompose and inhale, and enter the GC separation analysis with the carrier gas.

What are the main points of purging and collecting instrument during operation:

1. Purge efficiency and collection efficiency shall be considered for purging and collection. It is difficult to extract the purging components, which can increase the total volume of purging and improve the purging efficiency. At a constant purge flow, the purge time can be increased to achieve greater recovery. Increasing the purge flow rate can improve the purge efficiency of gases with boiling points below 35°C, but due to the increase in purge flow rate, these gases may reduce the collection efficiency through the collection trap. The effects of purge flow and purge time should be considered together with the recovery of all purge components.

2. Capture efficiency is related to the component to be measured and the adsorbent, such as vapor pressure. Specific surface area of the adsorbent. Interaction between ingredients and adsorbents. In general, the adsorbent will increase the capture efficiency of the component at a lower temperature. To prevent sorbent tube penetration, the capture temperature should be 25°C ± 2°C and should not exceed 30°C. Sometimes a cooling device is needed to capture certain compounds at room temperature.

3. The method of removing water in the process of purging and capturing mainly includes osmosis method and condensation method. Osmosis is very effective in removing water and polar substances in the sample, but when determining polar substances in samples such as ketone compounds, water cannot be removed by osmosis. Condensation is a commonly used method of water removal and does not affect the recycling of polar compounds.

4. In the process of purging and collecting, sample foaming will contaminate the purging and collecting system. The use of anti-foaming agents can inhibit foaming of the sample, but may change the properties of the sample matrix, leading to unknown errors in the analysis results. Filling the purge channel with inert glass spheres prevents foaming of the sample. The use of a foam filter not only prevents foaming of the sample, but also easily causes errors.