VERBESSERTE ZELLE ZUR ÜBERWACHUNG VON PHOTOCHEMISCHEN REAKTIONEN

摘要

An improved measurement cell and circuit for measuring the electrical characteristics of a liquid sample during exposure to radiation includes a glass cell formed of a main tube extending generally parallel to an elongated lamp emitting the radiation, and a pair of electrodes disposed axially within the sample tube. In the preferred embodiment, the ends of the cell are formed of glass twinbore tubing fused to the glass main tube, the bores retaining ends of the electrodes. Inlet and outlet tubes and a temperature sensing well may also be fused to the main tube. In an implementation for measurement of TOC in water by oxidation to CO2, the source comprises a low pressure mercury vapor lamp, and the electrodes are formed of solid Ti with catalytic TiO2 surfaces. The circuit used to monitor variation in electrical characteristics of the liquid during UV exposure controls flow of power to op-amps in order to multiplex a drive signal between the UV exposure cell, a calibration resistor, and a temperature sensor.