Measurement of dissolved ozone in sea water: A comparison of methods

Dissolved ozone levels in sea water can be quantified using various iodometric methods, the colourmetric N,N-diethyl-p-phenytenediamine (DPD) method, or by measuring oxidation/reduction potential (ORP). Dissolved ozone concentrations in sea water can be expressed in mg/l of total residual oxidants (TRO), ozone produced oxidants (OPO), residual ozone concentration (ROC) and ozone. This study compared commonly cited methods of ozone measurement for their ability to measure dissolved ozone and the ease with which they can be applied on-site in an aquaculture facility. The different units for expressing dissolved ozone concentrations were also examined. It is recommended that under non-laboratory (i.e., hatchery) conditions, a DPD 'total chlorine test' be used to measure dissolved ozone levels, and that the results be reported in TRO in terms mg/l of Cl-2. (c) 2005 Elsevier B.V. All rights reserved.