Chemoresistor for determination of mercury vapor
- This chapter presents a procedure to prepare and calibrate chemical sensor for mercury vapor and discusses application of the sensor for measurements of mercury vapor. The sensor is based on high affinity of gold to mercury and on chemoresistive properties of ultrathin gold layers: adsorption of mercury leads to increase in the surface resistance. However, this effect is not selective: similar changes are caused by adsorption of water vapor and sulfuric compounds. The use of monomolecular layer of alkylthiols as a filter excludes this interference completely. Sensor calibration is performed by thermoinjection of nanogram-amount of mercury quantitatively deposited by electrochemical reduction. It is found that the sensors display no sensitivity to such typical interferents of mercury chemoresistors based on uncoated gold as volatile thiols and water. Preliminary data demonstrate a possibility to measure Hg(0) even in aqueous solutions.