This standard applies to the determination of fluoride in organized emissions from fixed pollution sources in the atmosphere, but does not include fluorocarbons, such as Freon. When the sampling volume is 150L, the detection limit is 6 × 10 ^ -2 mg/m ³, and the measurement range is 1~ 1000 mg/m ³. The standard cites GB 16297-1996 "Comprehensive Emission Standard for Air Pollutants" and GB/T 16157-1996 "Determination of particulate matter (PM) in exhaust from fixed pollution sources and sampling methods for gaseous pollutants". In this standard, fluoride refers to the sum of gaseous fluoride and dust fluoride, where gaseous fluoride is absorbed by sodiumhydrate solution, and dust fluoride refers to fluoride dissolved in muriatic acid solution coexisting with particulate matter (PM). The principle of the test is to use a filter cartridge and sodiumhydrate solution to collect dust fluoride and gaseous fluoride, dissolve it with muriatic acid solution, prepare a sample, and then measure it with a fluorine Ion selective electrode. The reagent used is an analytically pure reagent, and the water is deionized water.