Separation Science

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)
  • Salt gradient ion exchange chromatography
  • 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

ER225 C4D Data System ER225 C4D Data System Includes PowerChrom software for data collection and analysis.
ER125 C4D Detector ER125 C4D Detector Can be used with third party data acquisition systems. Has analog and serial interface.
EA120 C4D Amp EA120 C4D Amp
Requires e-corder or PowerChrom system.
ER283 C4D System Bundle ER283 C4D System Bundle Includes EA120 C4D Amp and ER280 PowerChrom System.

C4D Capillary Headstages

ET120 Capillary Headstage 365 micro m ET120 Capillary Headstage 365 µm Connection to 365 µm outer diameter capillary.
ET120-150 Capillary Headstage 150 micro m ET120-150 Capillary Headstage 150 µm Connection to 150 µm outer diameter capillary.
ET120-150 Capillary Headstage 150 micro m ET125 General Purpose Headstage
for tubing sizes 1/16 inch (1.59 mm) OD or less (specify outer diameter required)

C4D Microfluidic Chip Platforms

ET225 ET225 Micronit Chip Electrophoresis Platform Platform for Micronit microfluidic chips ET145-4.

Microchip Electrophoresis with C4D

ER230 High Voltage Sequencer ER230 High Voltage Sequencer Dual high-voltage supply for microchip electrophoresis.
ET145-4 45mm CE Microchip Kit ET145-4 45mm CE Microchip Kit Four short Micronit microfluidic chips with integrated electrodes for C4D.
ET190-2 90mm CE Microchip Kit Two long Micronit microfluidic chips with integrated electrodes for C4D
EC20 Standard Test Solutions for C4D Applications EC20 Standard Test Solutions for C4D
 Solutions for testing a C4D system in electrophoresis experiments.
ER255 Dual HV Supply MCE System Bundle ER255
 		 Dual HV MCE Bundle Complete system for microchip electrophoresis (floating injections) includes: ER225, ER230, ET225, ET145-4 and EC20.
ER455 Quad HV Supply MCE System Bundle ER455

 		 Quad HV MCE Bundle Complete system for microchip electrophoresis (floating, pinched and gated injections) includes: ER225, 2 x ER230, ET225, ET145-4 and EC20.

 

blue border
blank