Segmented flow coil equilibrator coupled to a Proton Transfer Reaction
Mass Spectrometer for measurements of a broad range of Volatile
Organic Compounds in seawater
Abstract. Here we present a technique that utilises a segmented flow coil equilibrator coupled to a Proton Transfer Reaction-Mass Spectrometer to measure a broad range of dissolved organic gases. Due to its unique design composed of a segmented flow and a headspace-water separator, the equilibrator is highly efficient for gas exchange and has a fast response time (under 1 min). The system allows for both discrete and continuous measurements of volatile organic compounds in seawater due to its ease of changing sample intake and low sample water flow (100 cm3 min-1). The equilibrator setup is both relatively inexpensive and compact. Hence it can be easily reproduced and installed on a variety of oceanic platforms, particularly where space is limited. As a result of its smooth and unreactive surfaces, the segmented flow coil equilibrator is expected to be less sensitive to biofouling and easier to clean than membrane-based equilibration systems. The equilibrator fully equilibrates for gases that are similarly soluble or more soluble than toluene. The method has been successfully deployed in the Canadian Arctic. Here, some example data of underway surface water and Niskin bottle measurements in the sea ice zone are presented to illustrate the efficacy of this measurement system.