Development and validation of a new in situ technique to measure total gaseous chlorine in air

[摘要] Total gaseous chlorine (TCl g ) measurements can improve ourunderstanding of unknown sources of Cl in the atmosphere. Existingtechniques for measuring TCl g have been limited to offline analysis ofextracted filters and do not provide suitable temporal information on fastatmospheric processes. We describe high-time-resolution in situ measurementsof TCl g by thermolyzing air over a heated platinum (Pt) substratecoupled to a cavity ring-down spectrometer (CRDS). The method relies on thecomplete decomposition of TCl g to release Cl atoms that react to formHCl, for which detection by CRDS has previously been shown to be fast andreliable. The method was validated using custom organochlorine permeationdevices (PDs) that generated gas-phase dichloromethane (DCM), 1-chlorobutane(CB), and 1,3-dichloropropene (DCP). The optimal conversion temperature andresidence time through the high-temperature furnace was 825  ∘ Cand 1.5 s, respectively. Complete conversion was observed for sixorganochlorine compounds, including alkyl, allyl, and aryl C–Cl bonds, whichare amongst the strongest Cl-containing bonds. The quantitative conversionof these strong C–Cl bonds suggests complete conversion of similar or weakerbonds that characterize all other TCl g . We applied this technique toboth outdoor and indoor environments and found reasonable agreements inambient background mixing ratios with the sum of expected HCl from knownlong-lived Cl species. We measured the converted TCl g in an indoorenvironment during cleaning activities and observed varying levels ofTCl g comparable to previous studies. The method validated here is capable of measuring in situ TCl g and has a broad range of potential applications.

[学科分类] 内科医学