Four-stage cold trap atmosphere preconcentrator and concentration method thereof

Abstract

The invention provides a four-stage cold trap atmosphere preconcentrator and a concentration method thereof, and the method comprises the following steps: feeding a sample to be detected into the four-stage cold trap atmosphere preconcentrator so as to empty non-to-be-detected gas in the four-stage cold trap atmosphere preconcentrator; sample gas sample introduction is carried out on the emptied four-stage cold trap atmosphere pre-concentration instrument; partial low-carbon compounds and high-carbon compounds of the sample gas are respectively transferred through a four-stage cold trap atmosphere pre-concentrator; and simultaneously outputting part of low-carbon compounds and high-carbon compounds after the sample gas transfer operation through a four-stage cold trap atmosphere pre-concentrator. According to the four-stage cold trap atmosphere pre-concentration instrument, low-carbon compounds and high-carbon compounds are transferred separately, and sample water is separated out when the low-carbon compounds are transferred. The contradiction that the four-stage cold trap atmosphere preconcentrator needs to transfer a small amount of water and transfer all high-carbon compounds as much as possible is solved, so that the four-stage cold trap atmosphere preconcentrator achieves a better separation effect, and the accuracy of sample detection is further improved.

Description

technical field [0001] The invention relates to the field of chemical analysis, in particular to a four-stage cold trap atmospheric pre-concentrator and a concentration method thereof. Background technique [0002] At present, the concentration principle and operation method of atmospheric pre-concentrators that produce liquid nitrogen refrigeration are almost the same. They all use liquid nitrogen as a refrigerant and are divided into three stages of freezing and adsorption cold traps. The purpose is to remove the water in the sample gas containing VOC. , oxygen, nitrogen, carbon dioxide and inert gases, etc., only retain the VOC components to be used for analysis, VOC refers to the general term for volatile organic compounds. During the processing of VOC-containing samples, a three-stage cold trap atmospheric preconcentrator was used for processing. Because the sample gas has a certain humidity, and the water in the sample gas has a great influence on the life of the mass...

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Problems solved by technology

However, if the temperature rise is higher when the high carbon compound is transferred, the water is also partially vaporized, so that the water removal effect of the three-stage cold trap atmospheric pre-concentrator is poor; on the contrary, if the high carbon compound is transferred When the temperature rise during the transfer is low, the high-carbon compounds will be trapped in the three-stage cold trap atmospheric pre-concentrator, resulting in very short or even no peaks of high-carbon compounds in the sample, which will affect the accuracy of sample detection

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