Determination of CCl3F and CCl2F2 in seawater and air

摘要: An improved analytical technique has been developed for the rapid and accurate shipboard measurement of two anthropogenically produced chlorofluorocarbons (CFCs), CCl3F (F-11) CCl2F2 (F-12) in air seawater. Gas samples (dry or standard) are injected into a stream purified gas then concentrated low temperature trap. Seawater collected oceanographic Niskin bottles transferred glass syringes storage until analysis. aliquot approximately 30 cm3 seawater is introduced stripping chamber where dissolved gases purged with gas, evolved CFCs same cold The trap subsequently isolated heated, automatically by carrier precolumn chromatographic separating column. peaks detected an electron capture detector (ECD) their areas integrated digitally. CFC amounts calculated using fitted calibration curves, generated injection various multiple aliquots standard containing known concentrations CFCs. Preliminary concentration values these compounds printed at completion each Total analysis time water < 10 min, allowing detailed vertical profiles column overlying atmosphere to be determined within few hours hydrographic station. Typical relative deviations analyses near-surface equilibrium levels 1%. Limits detection both about 0.005 × 10−12 mol kg−1.