TVOC is an organic compound whose boiling point is not higher than 260 ℃ under the steam pressure of not less than 10Pa or 101.325kp standard atmospheric pressure at 20 ℃. Volatile organic compounds mainly include non methane total hydrocarbons (alkanes, olefins, alkynes, aromatic hydrocarbons), oxygenated organic compounds (aldehydes, ketones, alcohols, ethers, etc.), halogenated hydrocarbons, nitrogen-containing compounds, sulfur-containing compounds, etc. Studies have shown that the annual emission of v0cs in China is about 30 million tons, including 43% from industry, 28% from transportation, 15% from domestic sources and 14% from agriculture. The industrial emission sources are generally chemical industry, oil refining industry, chemical raw material production, pharmacy, coking, synthetic fiber, electronic manufacturing, automobile manufacturing, furniture manufacturing, wood industry, packaging and printing, equipment manufacturing, rubber industry, coating and paint industry, pesticide industry, etc. As one of the important subdivisions in environmental monitoring, VOCs market space is mainly reflected in air quality monitoring and pollution source monitoring in key areas; Its function can provide environmental protection departments with monitoring regional air quality status and monitoring enterprise pollution emission data; At the same time, it can also provide vouchers for environmental protection disputes; At present, the applicable industries for VOCs online monitoring include petrochemical industry, biopharmaceutical industry, packaging and printing, electronic semiconductor, surface coating, rubber and plastic products, furniture manufacturing, circuit board, automobile manufacturing and maintenance, etc. the applicable environmental monitoring is generally large-scale national standard air station, small early warning air station, sampling unit collects on-site tail gas or measured gas, and pretreatment unit cools, dehumidifies and filters dust, The temperature and humidity of the measured gas are kept constant within a certain range. The gas detection unit PID photo ion detection analyzes the transmitted gas, displays the measured gas concentration in real time on the display screen, and transmits the data signal to terminals such as PLC or computer. It can also be transmitted to the cloud server through wireless GPRS or network, or connected to the Environmental Protection Bureau through data acquisition instrument for real-time supervision.