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Ppt-level aqueous benzene detection with an UV-spectroscopy based portable sensor

With the ultimate goal of providing an on-site early-alert system for drinking water contamination by benzene, we have further developed our portable aqueous benzene sensor to reach sensitivity below the drinking water regulatory levels (5 ppb(v/v) in America). Prior to the UV detection, we added a new concentration stage composed of a moisture exchanger and a cell filled with zeolite adsorbent. Despite the high relative humidity of sample gas, the stage provides a two-orders of magnitude benzene concentration enhancement, leading to a 300-ppt(v/v) detection limit with 15-min measuring time. Combined with an in-line and continuous extraction system, we also demonstrated time-resolved monitoring at low-ppb aqueous benzene concentration levels.