Patent ID: 7598086

Claim:
A method of determining chemical oxygen demand of a water sample, comprising the steps of a) applying a constant potential bias to a thin layer photoelectrochemical flow cell, having a photoactive nanoparticulate semiconductive working electrode and a counter electrode, and containing a supporting electrolyte solution; b) illuminating the working electrode with a light source and recording the background charge produced at the working electrode from the supporting electrolyte solution; c) adding a 5 μl to 200 μl of water sample, to be analyzed, to the thin layer photoelectrochemical flow cell; d) illuminating the working electrode with a light source and recording the total charge produced with the sample; e) deducting the background charge from the total charge produced with the sample to obtain the net charge due to the oxidation of organic material in the sample; and f) determining the chemical oxygen demand of the water sample under exhaustive degradation conditions from the equivalent oxygen concentration consumed in the reaction as defined by the equation: Equivalent ⁢ ⁢ Oxygen ⁢ ⁢ Concentration ⁢ ⁢ ( mole ⁢ / ⁢ L ) = Q 4 ⁢ ⁢ FV where Q is the net charge, F is the Faraday constant and V is the sample volume.