Contactless Conductivity

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

  • Capillary Electrophoresis (CE)
  • Microchip Electrophoresis (MCE)
  • Ion Chromatography (IC) and High-Performance Liquid Chromatography (HPLC)
  • Flow Injection Analysis (FIA)

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 here for some application areas and here for C4D resources.

eDAQ products for C4D

Choose the C4D unit and the C4D headstage suitable for your application. All the C4D headstages work with each of the C4D units.

C4D units:

  • C4D Data System (ER225). Includes PowerChrom software for data collection and analysis.
  • C4D Detector (ER125). Can be used with third party data acquisition systems. Has analog and serial interface.
  • C4D Amp (EA120). Requires e-corder or PowerChrom system.

C4D headstages:

  • C4D Headstage (ET120) for capillary electrophoresis. Connects to 365 µm or 150 µm outer diameter diameter capillary.
  • C4D Planar Headstage (ET123) for ion chromatography/HPLC and Flow Injection Analysis. Connects to 1/16 and 1/32 inch tubing.
  • C4D Microfluidic Platform (ET121) designed for contactless conductivity detection on a microfluidic chip (lab-on-a-chip).

Bundles:


 
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