Simultaneous Determination of Chlorofluorocarbons and Sulfur Hexafluoride in Seawater Based on a Purge and Trap Gas Chromatographic System

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• 作者：Ming-Gang CAI^a ; ^b ; ^{mgcai@xmu.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Heng-Xiang DENG^a ; Peng HUANG^a ; Hong-Wei KE^a ; Xue-Hong ZHENG^a ; Wen-Quan LI^a
• 关键词：Sulfur hexafluoride ; Chlorofluorocarbons ; Purge and trap ; Gas chromatography ; Seawater
• 刊名：Chinese Journal of Analytical Chemistry
• 出版年：2016
• 出版时间：July 2016
• 年：2016
• 卷：44
• 期：7
• 页码：1003-1008
• 全文大小：968 K

文摘

Chlorofluorocarbons (CFCs) and sulfur hexafluoride (SF₆) are types of anthropogenic halogenated compounds, and are very important for ocean processes, including air-sea and water mass exchanges. Meanwhile, they can also be used to calculate some key physical and biogeochemical parameters such as the apparent oxygen utilization rate and anthropogenic CO₂. Compared to CFCs, SF₆ is quite difficult to measure in seawater due to its low solubility. However, it is useful to study the ocean processes based on both CFCs and SF₆. In this study, a purge and trap gas chromatography system was developed to simultaneously measure CFC-12 and SF₆ in seawater. The optimal conditions were as follows: trap temperature of −70 °C, purge time of 8 min, purge gas pressure of 310 kPa, desorption time of 30 s, desorption temperature of 90 °C. The method was simple and sensitive. The detection limit were 0.02 pmol kg⁻¹ for CFC-12 and 0.03 fmol kg⁻¹ for SF₆. The analytical precision of CFC-12 was ±1.2% and that of SF₆ was ±0.5%. The correlation coefficient (R²) values of all calibration curves were greater than 0.9995. This method was successfully used in the analysis of sea water samples collected during the 6^th Chinese Arctic Research Expedition.