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Contactless Conductivity Introduction

eDAQ supplies several products for Capacitively-Coupled Contactless Conductivity Detection (C4D). C4D can be used for:


Please see the full list of C4D products.


The basis of contactless conductivity meaurements is explained in Figures 1, 2, and 3:


Fig 1. C4D uses a transmitter electrode to subject a sample region to a large amplitude, high frequency electromagnetic signal. A corresponding, attenuated, AC signal registers at a receiver electrode.


Fig 2. The size of the received signal is affected by the conductivity of the sample.


Fig 3. The received AC signal is deconvoluted to convert the amplitude into a DC analog voltage signal appropriate for data collection.

As analyte ions pass into the detection region they cause small changes to the overall sample conductivity. Continous monitoring of the conductivity signal will show a series of peaks, the areas (or heights) of which are related to analyte concentration. The signal is processed like a conventional chromatogram.

The C4D electrodes do not make direct contact with the sample. Thus they are electrically isolated from the sample (ideal for electrophoresis detection), and electrode fouling is eliminated.

Since the the vast majority of analytes for CE are ionic, a C4D system functions as a 'universal' method of detection requiring minimal sample preparation. The technique can also be used in parallel with UV-visible absorbance, or fluorescent detection. Sensitivity is typically similar to UV-visible absorption detection. Click to view citations and C4D resources.



This page was last modified on: 05 Mar 2014 19:39:58