There are many methods for monitoring NMHC in ambient air and industrial waste gas, and Shanghai Xuansheng Scientific Instrument Co., Ltd. uses gas chromatography. The dual column dual hydrogen flame ionization detector gas chromatography method was used to measure the content of total hydrocarbons and methane, and the difference between the two was the content of NMHC. The NMHC measured under specified conditions is the total amount of hydrocarbons other than methane that shows a significant response to the gas chromatography hydrogen flame ionization detector, measured in carbon.