Apparatus for measuring the concentration of impurities within a substance

摘要

An apparatus is disclosed for measuring the concentration of impurities within a substance by the measurement of the reduction in freezing point of the substance. A container containing the substance is coupled to a temperature variation means such as a solid state thermoelectric device for cooling the substance within the container. A temperature sensor such as a thermistor is mounted in thermal contact with the substance for providing a temperature sensor output in accordance with the temperature of the substance. A first amplifier is connected to the temperature sensor for providing a first amplifier output in relation to the output of the temperature sensor. A second amplifier is connected for receiving the first amplifier output to provide a second amplifier output. Control means receives the second amplifier output for controlling the thermoelectric device in accordance with a preselected standard or program. The control means may be programmed for cooling the substance at a pre-established rate of temperature change. A third amplifier is connected for receiving the first amplifier output for providing a precision third amplifier output for indicating the precise concentration of impurities within the substance. A sample and hold and timing circuit may be included to receive the third amplifier output for indicating the trend of the concentration of impurities in the substance as a function of time during a continuous chemical process.