Figure 16–5: Peak height versus spacer thickness to the power -2/3
Decreasing the spacer thickness is limited by an increased pressure drop over the flow cell that
eventually leads to an obstruction of the flow. The minimum spacer thickness available is 25 µm.
Applying these small spacers should be done with care. Over-tightening of the bolts may cause
an excessive pressure buildup over the flow cell and increase the noise considerably.
Table 16–4: Flow cell volume
WE diameter (mm)
3.00
2.74
2.54
2.00
1.90
1.00
0.75
0.50
Spacer
(µm)
Cell volume (µL)
25
0.18
0.15
0.13
0.08
0.07
0.020
0.011
0.005
50
0.35
0.29
0.25
0.16
0.14
0.039
0.022
0.010
120
0.85
0.71
0.61
0.38
0.34
0.094
0.053
0.024
16.2 Reference electrodes
The VT-03 flow cell is available with an ISAAC (in situ Ag/AgCl) reference electrode, a salt bridge
Ag/AgCl reference electrode, or a HyREF reference electrode.
16.2.1 ISAAC reference electrode
The ISAAC reference electrode is in direct contact with the mobile phase, which contains chloride
ions. The chloride concentration determines the potential, so each time a fresh mobile phase is
prepared it should contain exactly the same concentration of chloride ions.
The standard electrode potential of the Ag/AgCl electrode (in 1.0 mol/L Cl solution) for the
following half-reaction is defined as E
0
:
December 16, 2021, 715007395 Ver. 00
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