Reactivity of Carbon Adsorbents Used to Determine Volatile Organic Compounds in Atmospheric Air

The surface reactivity of carbon adsorbents (carbon molecular sieves and graphitized carbons) used for analysis of volatile organic compounds in atmospheric air was studied using ¹⁸O as a labelling agent. The carbon adsorbent surface activated in a stream of inert gas at 350°C and then exposed to air is very active chemically. Apparently peroxide structures are formed. Owing to this activity the integrity of some analytes, for example dienes and alcohols, among others, is compromised. The active surface can react with the volatile organic compounds analyzed and even initiate free-radical polymerization. The consequences in analytical practice are discussed.