Setting Atlas Suppressor CurrentsDetector Control
Setting Atlas Suppressor Currents
For optimal suppressor performance, it is important to use the recommended suppressor currents for the target applications. The Chromeleon Program Wizard (see The Control Program 
The Program Wizard) guides you in setting the recommended current for the Atlas Electrolytic Suppressor. The wizard supplies a recommended current based on the eluent concentration and flow rate settings (see the table below). Chromeleon automatically enters the recommended current into the Program and applies that current to the Atlas Electrolytic Suppressor.
These settings are also used to set basic equilibration conditions for the suppressor (see Control The SmartStartup Wizard) or to select suppressor settings for shutdown or standby mode (see Control The SmartShutdown Wizard).
Caution:
It is possible to override the recommended current settings in the wizard by entering an alternate current value in the program file. However, to ensure the optimal performance of the suppressor, avoid applying excess current to it. Excess operating current leads to excess heat generation, which can reduce the suppressor lifetime and cause higher chromatographic baseline noise.
Atlas Electrolytic Suppressors have a maximum suppression capacity of 25 mN eluent at 1.0 ml/min, which is equivalent to 12.5 mM sodium carbonate for anion separations or 25 mM methanesulfonic acid (MSA) for cation separations at 1.0 ml/min.
Tip:
For gradient separations, use the highest eluent concentration in the gradient when you enter the eluent concentration in the wizard.
Examples of Recommended Operating Currents for Atlas Electrolytic Suppressors:
|
|
|
Flow Rate |
Current |
|
4-mm AS4A-SC |
1.8 mM Na2CO3/1.7 mM NaHCO3 |
2.00 |
36 |
|
2-mm AS4A-SC |
1.8 mM Na2CO3/1.7 mM NaHCO3 |
0.50 |
9 |
|
4-mm AS9-HC |
9.0 mM Na2CO3 |
1.00 |
60 |
|
2-mm AS9-HC |
9.0 mM Na2CO3 |
0.25 |
15 |
|
4-mm AS14 |
3.5 mM Na2CO3/1.0 mM NaHCO3 |
1.20 |
32 |
|
2-mm AS14 |
3.5 mM Na2CO3/1.0 mM NaHCO3 |
0.30 |
8 |
|
3-mm AS14A |
8.0 mM Na2CO3/1.0 mM NaHCO3 |
0.5 |
28 |
|
4-mm CS12A |
22 mM MSA |
1.00 |
72 |
|
3-mm CS12A-5 mm |
20 mM MSA |
0.50 |
32 |
|
2-mm CS12A |
22 mM MSA |
0.25 |
18 |
For other column and eluent conditions, the recommended current for the Atlas electrolytic suppressors can be calculated using the following equation:
Current (mA) = 2 x 1.67 (mA*min /mN*ml) x [eluent (mN)] x flow rate (ml/min)
For anion separations:
[eluent (mN)] = 2 x [CO32-(mM)] + [HCO3-(mM)] + [OH-(mM)]
For cation separations:
[eluent (mN)] = 2 x [H2SO4(mM)] + [MSA (mM)]
(Where: [ ] enclosing an ion or eluent indicates concentration.)
The following table lists the maximum operating currents for the Atlas Electrolytic Suppressors under various column diameter and flow rate conditions.
Maximum Operating Currents for the Atlas Electrolytic Suppressors:
|
Separation Column |
Flow Rate (ml/min) |
Maximum Current (mA) |
|
2-mm column |
0.25 to 0.50 |
30 |
|
3-mm column |
0.50 to 1.00 |
50 |
|
4-mm column |
1.00 to 2.00 |
100 |
Once the recommended suppressor current is determined, turn on the pump flow and apply the current to the suppressor.