The eDAQ 150 micron C4D headstage

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The eDAQ 150 μm C4D Headstage
Three cations

A C4D (capacitively-coupled contactless conductivity detector) headstage is described for use with 150 μm outer diameter capillaries and for the analysis of three cations.


eDAQ has developed a C4D headstage for use with capillaries with an outer diameter of 150 μm. The headstage was used for the analysis of a solution containing potassium, sodium and lithium chlorides dissolved in MES/His background electrolyte (BGE). The headstage can be used with any eDAQ C4D hardware.

A limit of detection of 3 µM was obtained.


  • Capillary from Polymicro Technologies, 150 µm OD, 76 µm ID, 60 cm long.
  • Sample: 200 µM Na, K, Li (as chloride salts) dissolved in water and BGE
  • BGE: 20 mM of 2-(N-morpholino)ethanesulfonic acid and L-histidine
  • The new capillary was prepared by flushing with 0.1 M HCl, water, 0.1 M NaOH, water, then BGE, for 5 minutes each
  • Instrument: built in-house at University of Basel
  • Injection: 10 s siphoning at 10 cm height
  • Separation voltage: 25 kV (10 μA current)
  • C4D settings: 700 kHz, 100 V, gain ON

eDAQ Equipment Required