Optical hydrogen peroxide sensor for measurements in flow

An optical hydrogen peroxide (H₂O₂) sensor is presented. The sensor is based on catalytic degradation of H₂O₂ and the detection of produced oxygen (O₂) with a phosphorescent sensor. A novel aspect of the sensor is removal O₂ from the analyte solution in flow. This allows the use of a more sensitive O₂ sensor. Thereby, a better resolution at lower H₂O₂ concentrations is achieved. Sensor spots are integrated in a flow-through cell, and H₂O₂ is measured in flow between 10 and 80 µL/min. The catalytic activities of previously reported catalyst are tested. RuO₂ and silica supported platinum nanoparticles are applied in the sensor with limit of detections of 0.16 and 0.17 µM H₂O₂, respectively. The sensor can measure reliably between 1 and 200 µM H₂O₂. The concentration range can be extended to 1000 µM H₂O₂ by exchanging the O₂ sensor. Interfering species (NaONOO, NaOCl, t-BuOOH, and ascorbic acid) are tested and show only minor cross-sensitivities. The sensor is applied at-line in a model batch reactor with glucose oxidase to showcase production of H₂O₂ from glucose.