What are VOCs?
VOC is the abbreviation of Volatile Organic Compounds, which are organic substances with boiling points ranging from 50 to 260 degrees under normal pressure. It was first proposed by the United States Environmental Protection Agency (EPA) with the aim of monitoring air pollution by studying volatile organic compounds in the ambient air. VOCs are a type of volatile organic substances.
What are the environmental monitoring standards in China?
In the early days, China’s environmental monitoring standards referred to and learned from the experience of the US EPA, such as TO14 and TO15. Subsequently, in 2015, the Ministry of Environmental Protection of China issued and implemented HJ759 “Ambient Air Volatile Organic Compounds Can Sampling/Gas Chromatography-Mass Spectrometry”, and in 2018, it released the “Monitoring Plan for Ambient Air Volatile Organic Compounds in Key Areas in 2018″. Both of these standards detail the targets that need to be closely monitored in the ambient air.
Overview of the “Monitoring Plan for Volatile Organic Compounds in Ambient Air of Key Areas in 2018″
The “Monitoring Plan for Volatile Organic Compounds in Ambient Air of Key Areas in 2018″ is a plan issued by the Ministry of Environmental Protection. Its aim is to standardize and strengthen the monitoring of volatile organic compounds in ambient air of key areas, accurately assess and predict air quality conditions, and provide support for formulating scientific and effective ambient air quality management measures. This plan has made detailed regulations on the monitored cities, monitoring items, time frequency and operation procedures, etc. The monitored cities include municipalities directly under the Central Government, provincial capitals, cities with independent planning status and prefecture-level cities, totaling 59. The monitoring items include VOCs with strong photochemical reactivity or those that may affect human health, such as alkanes, alkenes, aromatic hydrocarbons, oxygen-containing volatile organic compounds (OVOCS), halogenated hydrocarbons, etc. This plan requires each city to formulate specific monitoring plans based on their actual conditions, determine the monitoring points and time frequencies, and conduct monitoring in accordance with the prescribed operating procedures. At the same time, it is required that all cities strengthen the maintenance and management of monitoring equipment to ensure the accuracy and reliability of monitoring data. In addition, the plan also requires each city to enhance cooperation and exchanges with other regions and the international community to jointly promote the continuous improvement of environmental air quality.
Detailed description of environmental monitoring standard gases:
Among the standard gases stipulated for the detection of 67 target substances in China, 64 components are the TO15-65 component standard gases under the standards of the United States Environmental Protection Agency (EPA). The three components not included: dimethyl disulfide, dimethyl sulfide, and methyl mercaptan need to be prepared separately because dimethyl disulfide will react with alcohols, causing instability of the standard gas. In addition, the internal standard gases stipulated in the national standards of our country, Moturunda, can also be supplied.
HJ759 specifies the canisters sampling/gas chromatography-mass spectrometry method for the determination of volatile organic compounds in ambient air. The principle of the method is as follows: ambient air samples are collected in stainless steel canisters with inert inner walls, concentrated in cold traps, desorbed by heat, and then separated by gas chromatography. The samples are detected by a mass spectrometry detector and qualitated by comparing with the mass spectra and retention times of standard substances, which is the internal standard method Quantitative. The aim is to control the target monitoring substances in the ambient air at the ppb or even ppt level.
Post time: May-29-2025