Patent ID: 6863801

Claim:
An apparatus for determining a concentration of a reduced form or an oxidized form of a redox species in a liquid sample, the apparatus comprising: (a) a hollow electrochemical cell having a working electrode and a counter or counter/reference electrode wherein the working electrode is spaced from the counter or counter/reference electrode by less than 500 μm; (b) means for applying an electric potential difference between the electrode; and (c) means for electrochemically determining the concentration of the reduced form or the oxidized form of the redox species in the liquid sample comprising: (i) means for determining a change in current with time after application of the electric potential difference and prior to achievement of a steady state current; (ii) means for estimating a magnitude of the steady state current; and (e) means for obtaining from the change in current with time and the magnitude of the steady state current, a value indicative of the concentration of the reduced form or the oxidized form the redox species.