A kind of vocs online pretreatment device in water

Abstract

The invention discloses an online pretreatment device for VOCs (volatile organic compounds) in water. The online pretreatment device for the VOCs integrates the functions of collection, enrichment, thermal desorption, back-blowing sample introduction and the like into a whole. The online pretreatment device can be directly connected with a gas chromatographic instrument for completing online monitoring of the volatile organic compounds in the water. The device adopts modular structural design, and the different processes are completely by valve switching. The device can automatically perform waste liquid discharge and cleaning of a sample pipe after automatic pretreatment, the purification of a pipeline and the online aging of an adsorption column can be simultaneously performed, the mutual interference is avoided, and the analysis period is shortened. The device has the advantages of simple structure, simplicity in operation, economy and practicality and does not need an additional water removing device and an automatic sample introduction device, and the device is very suitable for online continuous monitoring of the VOCs of water quality.

Description

technical field [0001] The invention relates to the technical field of on-line monitoring instruments, in particular to an on-line pre-treatment device for VOCs in water. Background technique [0002] Volatile organic compounds (VOCs) are common organic pollutants in water. They mainly come from factory wastewater discharge, urban sewage discharge and tap water disinfection. Volatile organic compounds are highly volatile, soluble in lipids, and easily absorbed by skin and mucous membranes. At the same time, many VOCs can cause cancer, teratogenicity or mutagenesis, which is extremely harmful. Therefore, online detection of VOCs in environmental water is very necessary. It is convenient to reflect the change of water quality in real time. [0003] The content of volatile organic compounds in environmental water is low, and it is extremely difficult to directly measure them. It is necessary to select a suitable sample pretreatment method for separation and enrichment to reach...

AI Technical Summary

Problems solved by technology

The disadvantage of static headspace is that the analysis time is long. In order to improve the sensitivity, a large volume of sample injection is often required, resulting in a large initial broadening of the chromatographic peak of volatile organic compounds. During the sample injection process, volatile organic compounds condense in the tube wall or syringe, and there is a memory effect. , high detection limit

Purge and trap is widely used in the analysis of VOCs in environmental water due to its high enrichment efficiency, low pollution, and easy operation. It is currently the standard method recommended by the US Environmental Protection Agency (US Environmental Protection Agency, US-EPA). Most of the instruments are imported from abroad, and there are no mature instruments in China

Imported instruments are expensive and costly to use

The purge and trap instrument needs to be equipped with an autosampler. Usually, the structure of the autosampler is complex, the instrument is expensive, and the autosampler injects samples according to the position of the sample bottle, which requires manual participation in sample preparation. It is not suitable for unattended Online Monitoring

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