The Dionex CDRS 600 and Dionex CERS 500e use water as the regenerant and can provide continuous suppression. The following table lists the eluent concentrations and flow rates of commonly used mobile phases used in cation separations and the optimum / recommended current level to suppress the eluent. The operation of the Dionex CDRS 600 and Dionex CERS 500e requires a constant flow of water over the electrodes in a direction that is countercurrent to the flow of the eluent.

In the AutoSuppression Recycle Mode, the eluent leaving the conductivity cell is recycled through the regenerant chambers as the water supply. This eliminates the need for an external regenerant water supply and delivery system. When the Dionex CDRS 600 and Dionex CERS 500e are operating in this mode, the amount of water flowing through the regenerant chambers is limited to the eluent flow rate. The AutoSuppression Recycle Mode cannot be used with eluents containing any organic solvents.

The AutoSuppression External Water Mode requires an external source of deionized water for the regenerant chambers. When the Dionex CDRS 600 and Dionex CERS 500e is operating in this mode, the amount of water flowing through the regenerant chambers is independent of the eluent flow rate. Because of this, higher regenerant flow rates are achievable. See the following table.

Higher regenerant flow rates translate into improved signal-to-noise ratios compared to the AutoSuppression Recycle Mode. The AutoSuppression External Water Mode is the mode used if organic solvents (up to 40%) are present in the eluent. It eliminates the potential for buildup of contaminating ions resulting from the oxidation of solvents.

Optimum Current Settings for the Dionex CDRS 600 (Legacy Mode) and Dionex CERS 500e in the AutoSuppression Recycle and External Water Modes

Column

Eluent

Eluent Flow Rate (mL/min)

Optimum Current (mA)

(2 mm)

(4 mm)

(2 mm)

(4 mm)

CS12A

20 mM MSA

0.25

1.0

15

59

33 mM MSA

0.25

1.0

25

98

CS12A-5μm

20 mM MSA

0.51)

 

30

 

33 mM MSA

0.51)

 

49

 

CS14

10 mM MSA

0.25

1.0

8

30

CS15

10 mM H2SO4/9% AcN2)

0.3

1.2

18

71

14 mM H2SO4

0.3

1.2

25

99

CS16

30 mM MSA

0.361)

1.03)

32

89

48 mM MSA

0.361)

1.03)

51

142

CS17

6 mM MSA

0.25

1.0

5

18

40 mM MSA

0.25

1.0

30

118

CS18

5 mM MSA

0.25

 

4

 

CS19

8 mM MSA

0.25

1.0

6

24

60 mM

0.3

1.2

53

212

The Dionex CDRS 600 and Dionex CERS 500e are not compatible with legacy systems that only provide discrete (50, 100, 300 and 500 mA) current settings. For optimum performance, it is recommended to use a Dionex RFC-10 or Dionex RFC-30 power supply with these systems to provide graduated current control with the optimum setting.

External Water Flow Rates for Dionex CDRS 600 and Dionex CERS 500e (4 mm and 2 mm)4)

Minimum External Water Flow Rate

Recommended External Water Flow Rate

Maximum External Water Flow Rate

Equivalent to the eluent flow rate

2x the eluent flow rate

2 mL/min (2 mm suppressors)
5 mL/min (4 mm suppressors)