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How does a conductivity detector work?

Working principle and structure of conductivity detector of ion chromatograph

The conductivity detector of the ion chromatograph is based on the conductivity of the ionic compound solution, and its conductivity is related to the nature and concentration of the ions. The conductivity detector is a general-purpose detector for ion chromatography. Generally speaking, ionic substances can be measured by the conductivity method, but the conductivity of the solution is the sum of its various ions, and the solvent itself is used for ion separation. High conductivity will cover the conductivity of the ions in the medium to be measured, so it can only be detected when one ion conductivity is absolutely dominant
#01.The working principle of the conductivity detector
  • When a voltage is applied to the two electrodes of the conductivity cell, the anions in the solution move to the anode, and the cations move to the cathode. The number of ions in the electrolyte solution and the movement rate of ions determine the resistance of the solution. The movement rate of ions depends on the charge and size of the ions, the type of medium, the temperature of the solution, and the ion concentration. The applied voltage can be a DC voltage, a sine wave or a square wave voltage. When the applied voltage is determined, the current value in the circuit can be measured, that is, the conductance value can be measured.
#02.Conductivity detector structure
  • The conductivity detector is composed of a conductivity cell, an electronic circuit, a conversion sensitivity device and a digital display device. The conductivity cell is the core part. The basic structure of the conductivity cell is to place two electrodes in the effluent of the chromatographic column, and then measure the conductivity of the solution through an electronic circuit. The detection volume can reach microliters or even nanoscale.
#03.The characteristics of the conductivity detector
  • High sensitivity, the lower limit of detection is generally nanogram level, sometimes up to picogram level.
  • It has good selectivity and can measure extremely trace amounts of electroactive substances in a large number of non-electroactive substances.
  • Wide linear range.
  • simple structure, easy to operate automatically
[caption id="attachment_154" align="alignnone" width="443"] *The product in the picture is IC6600[/caption]

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