Determination of halocarbons in air by using adsorbent collection/solvent extraction/GC

A simple method was developed for the determination of avarage ppt-ppb concentrations of halocarbons (trichlorofluoromethane, 1, 1, 2-trichloro-1, 2, 2-trifluoroethane, chloroform, 1, 1, 1-trichloroethane, carbon tetrachloride, trichloroethylene and tetrachloroethylene) in air for about a day. A glass tube (2.6 mm i.d.) packed with 60 mg of Carbosieve G (60/80 mesh) was used for collection of halocarbons. Sample air was dehumidified by magnesium perchlorate and was supplied to this tube at a constant flow rate (0.1-0.2 1/min) for 24 h by diaphragm air pump with two buffer tanks to suppress pulse waves. After collection, the adsorbent was transferred to a sample vial(hole cap, Teflonlined silicone septum) and 5 ml of toluene was added to extract halocarbons. Amounts of halocarbons were determined by GC equipped with electron capture detector. The recoveries were up to 88%, and relative standard deviations were 2.4-7.5%.