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Detectores de condutividade sem contato C4D

Detectores de condutividade sem contato C4D

Contactless Conductivity Detectors C4D

eDAQ supplies Capacitively-Coupled Contactless Conductivity Detectors (C4D) which can be used for capillary electrophoresis, microchip electrophoresis, chromatography and flow injection analysis.

Put together your C4D system by selecting:

  • One C4D unit, depending on which software you wish to use and how many C4D channels are required, and
  • One or more C4D headstage/platform, depending on your application and which capillary/tubing/chip is being used.

All the C4D headstages/platforms work with each of the C4D units. If you have a novel application, look at our custom-made systems and contact us.


C4D Units

ER225  Contactless Conductivity C4D System ER225 C4D Data System
Includes PowerChrom software for data collection and analysis.
Has digital outputs.
ER815 C4D Contactless Conductivity Detector ER815 C4D Detector Single-channel contactless conductivity detector.
ER825 C4D Multi-Channel Contactless Conductivity Detector ER825 C4D multi-channel Detector Record the conductivity at up to eight positions on a capillary or tubing.

C4D Headstages

ET120 Capillary Headstage 365 micro m ET120 Capillary Headstage Connection to 365 µm outer diameter capillary.
ET125 General Purpose C4D Monitor Headstage ET125 General Purpose C4D Monitor Headstage For tubing sizes 1/16 inch (1.59 mm) OD.
ET130 IC HPLC C4D Detector Headstage ET130 IC/HPLC C4D Detector Headstage For ion chromatography and flow injection analysis.
ET131 Configurable C4D Detector Monitor Headstage ET131 Configurable C4D Detector/Monitor Headstage Factory-configurable to meet customer defined applications.

Custom-made C4D Systems

C4DSPL  Custom-Made Contactless Conductivity Detectors C4DSPL Custom-Made C4D Contactless Conductivity Detectors designed for your application.
ER818  Octal Contactless Conductivity System ER818 Octal Contactless Conductivity System Measure conductivity in pipette tips, melting point tubes, NMR tubes or capillaries


C4D Platform for Microfluidic Chips

ET225 ET225 Microchip Electrophoresis Platform Platform for Micronit microfluidic chips ET145-4 and ET190-2.

 Microchip Electrophoresis with C4D

ER455 Quad HV Supply MCE System Bundle ER455 Microchip Electrophoresis Kit Complete system for microchip electrophoresis.
ER430 High Voltage Sequencer ER430 High Voltage Sequencer High-voltage supply for microchip electrophoresis.
ET145-4 45mm CE Microchip Kit ET145-4 45mm CE Microchips Four short Micronit microfluidic chips with integrated electrodes for C4D.
ET190-2  Micronit CE Chip for C4D (90 mm) ET190-2 90mm CE Microchips Two long Micronit microfluidic chips with integrated electrodes for C4D.
EC20 Standard Test Solutions for C4D Applications EC020 Standard Test Solutions for C4D Solutions for testing a C4D system in electrophoresis experiments.

C4D Accessories

EA025 Headstage Module Allows connection of C4D headstages to ER825.
EA010 GP Analog Input Module To connect voltage signals and isoPods to ER825.
EC1208 Headstage cable with DIN connector Cable to connect headstages to ER225 (included with ER225).
EC1210 Headstage cable with LEMO connector Cable to connect headstages to ER815 and ER825 (included with ER815 and ER825).
ES280 PowerChrom Software For the collection and analysis of capillary electrophoresis, microchip electrophoresis, HPLC and other chromatography-type data (included with ER225, ER815R and ER825R).
ES500 Chart & Scope Software For the collection and analysis of flow injection analysis data and conductivity monitoring applications (included with ER815C and ER825C).

Measuring the Conductivity of a Liquid in a Pipette Tip


The conductivity of a liquid inside a pipette tip can be measured using the ER818 Octal Contactless Conductivity System.


The ER818 offers a method to measure the conductivity of a liquid inside a pipette tip. This can be integrated into an automated robotic system, which delivers the pipette tip into the Octal headstage. Measuring the conductivity directly in the pipette tip, instead of transferring the liquid to a measuring vessel, has a number of advantages:

  • Low sample volumes
  • Low sample wastage
  • Zero cross-contamination

The system has a conductivity range typically of 100 µS/cm to 10,000 µS/cm (the range is determined by the inner diameter of the sample tube).


Hamilton pipette tip and the positioning of the C4D electrodes (in red)

The system uses a capacitively-coupled contactless conductivity measurement (C4D). This applies a high frequency signal to an excitation electrode on the outside of the pipette tip. This couples the signal to the sample by capacitive-coupling. A detection electrode, located some distance from the sample, measures the resulting current. The current is proportional to the sample conductivity. The measured quantity will depend on the physical dimensions of the test volume and its conductivity.


Typical sample mediums

Other possible sample mediums. Typical sample mediums are shown in the figure. All are based on individual samples, except for the 1600 µm outer diameter (OD) capillary, which also allows for a continuous conductivity measurement to be made as the sample flow through the capillary.

1. Straight pipette tip

2. Tapered pipette tip

3. Capillary tubing with 1600 µm OD

4. Melting point disposable glass tube with 1600 µm OD

5. NMR tube with 5 mm OD


Equipment setup with ER815 and ET128

Equipment Required

  • ER818 Octal Contactless Conductivity System, which includes:
    • ER815 Contactless Conductivity Detector
    • ET128 Octal headstage
  • A computer with Chart software or your own software to record the data (for example, Tera Term, LabVIEW, C#, WinWedge or HyperACCESS)
  • Your pipette tips with samples
  • A standard solution with conductivity in the middle of the measuring range, say 5 mS/cm

Experiment Procedure

A Quick Start guide describes how to connect the system, how to use Tera Term software to calibrate the system using a standard solution, how to adjust the gain and measure the conductivity of an unknown sample. The Quick Start guide can be downloaded from the manuals webpage.




The volumes of the liquids involved in these measurements are very small and subject to temperature variation. Typically there will be a 4 to 5 °C temperature difference between the ambient laboratory air and the internal temperature of the ET128 Octal headstage. This corresponds to a potential error in conductivity measurement of approximately 5-6%. Since the internal temperature of the headstage is available, temperature compensation can be performed.

Allowing some time for the temperature to equalise can also help in reducing the temperature error. Another approach is to make the conductivity measurement as quickly as possible, before the sample temperature increases.

Use of a Reference Channel

In some applications where small changes in conductivity are to be measured, a reference channel can be used increase the sensitivity of the system and allow for temperature compensation. For example, if the conductivity of the unknown solutions are in the range 2 to 4 mS/cm, a reference solution of 3 mS/cm is selected and placed in the reference channel of the ET128 Octal headstage. This subtracts the reference conductivity value from the unknown solution's conductivity value, so that only the difference is displayed. An advantage of this technique is that any temperature drift in the reference will be removed from the unknown solution, thereby providing temperature compensation.



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