Measurement of organic compounds in air using activated carbon coated sensor

An activated carbon coated sensor of a quartz crystal oscillator is developed to utilize in the determination of organic substance contained in air. The sensor is made of readily available materials and is prepared from a simple process. The detection performance of the sensor is examined by applying it to n-heptane, acetone and ethanol vapor containing air system flowing at the rate of 0.4 L/minute. From the variation of oscillation frequency, it is found that the variation is proportional to concentration of the organic vapor for all three systems. Also, the sensor shows good recovery to the initial value when pure air is provided. The sensor sensitivity is the highest with ethanol, n-heptane is the next and acetone is the lowest. The ruggedness of the sensor is proved from implementing the sensor in a flow system. Since the sensor is produced from thermal treatment, it can be utilized in dry and temperature varying system. In addition, the sensor is simply regenerated by thermal treatment in a drying oven. The developed sensor is stable and inexpensive.