Patent ID: 8900440

Claim:
Process for detecting one or more chemical or biological species within a liquid, wherein the species either reacts in a redox reaction or directly or indirectly generates a molecule that reacts in a redox reaction, wherein current generated by said redox reaction is detected at the surface of at least one electrode, comprising the following steps: positioning a quantity of the species or molecule, which quantity varies over time, on, at or in the proximity of the at least one electrode within a period t 1 -t 1 ′-t 2 by flowing a liquid over the at least one electrode during a time period t 1 -t 1 ′ and stopping the liquid at the time t 1 ′, multiple switching of the at least one electrode back and forth during the period t 1 -t 1 ′-t 2 between two different potentials such that relative to a reference electrode, it assumes potentials that are in the range of or above the oxidation potential of said species or of said molecule or are in the range of or below the reduction potential of said species or of said molecule, as a result of which said species/said molecule is alternatingly reduced and oxidized, detecting the current generated by the repeated reduction and oxidation of the species/molecule in the at least one electrode over the period t 1 -t 1 ′-t 2 , measuring the current flow in the at least one electrode during the time interval t 1 -t 1 ′-t 2 , plotting the current flow during the time interval t 1 -t 1 ′-t 2 over time, and adding up the absolute values of the current signals, whereby a curve is obtained, which indicates the absolute value of the current flow over time, characterized in that it is observed for the qualitative detection of the species whether the curve after stopping the liquid is higher in the range t 1 ′-t 2 than the curve prior to stopping the liquid in range t 1 -t 1 ′, or that after stopping the liquid the slope of the current values in range t 1 ′-t 2 or the integral under the current values is measured and compared with reference values for a quantitative detection of the species.