A Purge and Trap Gas Chromatographic Method for Detection of Chlorofluorocarbons in Seawater

A purge and trap system was developed for the detection of chlorofluorocarbons (CFCs) in seawater. The optimized operating conditions for the purge and trap system were: a trap temperature of −60 °C, purge time of 8 min, purge flow rate of 20 mL min−1, desorption time of 1.5 min, and desorption temperature of about 130 °C. The method was simple and sensitive: the limits of detection of CFC-11, CFC-12, CFC-113 and CCl4 were 0.004, 0.008, 0.001 and 0.006 pM and their recoveries were 99.92% ± 1.77%, 98.77% ± 1.50%, 98.95% ± 3.92% and 97.13% ± 1.78%, respectively. The R2 values of all the calibration curves were greater than 0.99. This method was successfully used in the analysis of the samples collected in Prydz Bay during the 27th Chinese Antarctic Research Expedition.

Typical chromatograms for seawater sample, standard gas and blank. The chromatograms are plotted with about 0.1 V offset between them. The baseline offset in the vicinity of the CFC-11 peak is due to change of the carrier gas flow.