Submersible Online Oxygen Removal System Coupled to an in Situ Voltammetric Probe for Trace Element Monitoring in Freshwater

A new online oxygen removal system specifically built to allow in situ deoxygenation of freshwater before in situ voltammetric detection of trace elements using a submersible probe is described. It is based on the permeation of oxygen through a silicone tubing surrounded by an enzymatic cross-linked O2 scavenging gel. The main advantages of the enzyme cross-linked gel compared to the chemical O2 reducing solutions proposed in the literature for laboratory online deoxygenation coupled to other devices are as follows: (i) ease of preparation and storage under normal room condition, (ii) good long-term stability (maximum time tested 1 month), (iii) no formation of insoluble oxidized chemical compounds adsorbed on the external silicone tubing wall that may interfere with the O2 diffusion, and (iv) easy in situ applications thanks to the convenience of chemical gel for transport and pressure compensation. Detailed description of the construction of the system as well as the systematic laboratory tests performe...