| Abstract
| - The hydroperoxyl radical (HO2) is one of the mostabundant free radicals in the atmosphere, where itparticipates in a series of photochemical reactions thatdetermine the fate of natural and anthropogenic emissions. In addition, HO2 is found in droplets and surfacewater as a result of photochemical formation and gas-phase scavenging. We describe a quantitative method fordetermining trace concentrations of HO2 radicals thatexploits the chemiluminescence produced upon reactionwith a synthetic analogue of luciferin from the crustaceanCypridina. The technique is linear at least up to 1 μMHO2(aq) and has a minimum detection limit of 0.1 nM.A unique feature of this analysis is a calibration methodusing stable aqueous HO2 standards produced in submicromolar concentrations using 60Co γ-radiolysis. Theadvantage of this method in comparison to others inconsideration of field deployment is its simplicity, lowcost, and minimal size and power requirements. Oneintended application of this technique is the measurementof atmospheric HO2 radicals following collection intoaqueous solution.
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