Utilization of Integrated AM Receiver Circuit in Contactless Conductivity Detector for Detections in Solution
UNESCO Laboratory of Environmental Electrochemistry, Department of Analytical Chemistry, Charles University, Prague, Czech Republic
The integrated circuit TDA 1072A (Philips) was tested in signal processing in a contactless conductivity detector. The detection cell (consisting of two tubular electrodes placed on the outer wall of a PTFE tube) was connected between the sine-wave generator output and antenna input of the circuit. The analytical signal, a DC voltage, was taken from the output of a field intensity indicator. For the sine-wave input of the voltage frequency 1330 kHz and amplitude 0.25 V(pp), a nonlinear dependence of the signal on the solution conductivity was obtained in the range from ca. 25 to 700 μS cm-1, corresponding to the KCl concentration from 2.10-4 to 5?10-3 mol l-1. The relative standard deviation of the conductivity values was ca. 1 %. The detector was used for evaluation of drinking water.
Full text (PDF)