Based on the work of Seymour, et al. the electrochemical pH control method based on oxygen evolution was employed to locally control the pH for chlorine analysis within a channel without any fluid flow. This allowed electrochemical pH control of samples via the hydroylysis of water; leaving a net excess of protons. Similarly, the voltage at which the gold oxide reductive peak minimum occurred was used to approximate the local pH at a sensor. This approach was benchmarked against a set of know standards using a chemically controlled sample altered using different buffers. The targeted pH for chlorine detection was selected to be pH 3 as this was shown to be an area of high specificity for hypochlorous acid detection by Seymour, et al. A fixed potential bias of 1.6V was applied to WE2 to drive the local pH down to 3. Initial scans were performed in a known concentrations of free-chlorine added to ADW, which was electrochemically acidified to pH 3, in order to establish the appropriate cyclic voltammetry parameters. Working chlorine samples were prepared by diluting Milton Sterilising Fluid (2% Sodium Hypochlorite) to the desired concentration. The concentration of free-chlorine in these samples were then measured and confirmed using a standard commercial free-chlorine colorimeter (Pocket Colorimeter II 58700-00 with CL2 Test Kit), prior to electrochemical analysis. CV's were performed in the voltage range 0.85 V to -0.2 V (versus Pt pseudo-reference) at a 50 mV/s scan rate. All scans were repeated in quadruplet, with the first scan disregarded as a conditioning step and the subsequent three scans averaged. Cleaning scans were performed in-between each concentration to prevent any possible electrode fouling and improve reproducibility. These scans consisted of disconnecting WE1 and applying a typical CV 0.85 V to -0.2 V (versus Pt pseudo-reference) was applied to WE2 for 4 scans at a 50 mV/s scan rate. By applying these scan parameters to WE2, any potential fouling was minimised, ensuring a relatively constant electrode surface across all concentrations. WE1 was left disconnected to minimise unnecessary usage and therefore prolong the sensor lifespan.