Development of amperometric arsine gas sensor using gold-modified diamond electrodes

Amperometric gas sensor of arsine was developed using gold-modified diamond electrodes as the working electrodes. The detection method was conducted in high concentration of H2SO4. The reaction was declared based on two oxidation steps, involving oxidation of As3− to As0 at mild potential in strong acid, followed by electrochemical oxidation of As0 to As3+ at gold-based electrodes. Linear calibration curve was observed in the concentration range of 5–50 ppb (r2 = 0.985) with detection limit of ∼4.43 ppb (S/N = 3). Current decreasing of measurement was found ∼5.5% for 5 measurements. However, better stability was observed after the 5th measurement, indicated that the sensor could be applied for long time measurement. Investigation to several possible interference gasses, i.e. SO2, H2S, NO, NO2, CO, O3 and H2 indicated no significant interference of the gas to arsine measurements.