The Dionex DRS 600 requires electrical current to be set during operation. Optimal current improves performance for the Dionex DRS 600 (Legacy Mode), Dionex ERS 500e and Dionex AERS 500 Carbonate suppressors. Excess current through the suppressor devices causes excess heat generation and over time will cause the ion exchange materials to degrade, thus shortening suppressor lifetime.

Excess current can also cause poor recoveries of certain analytes, particularly magnesium, manganese, and phosphate. No more than 10% above the optimum current setting is recommended for extended periods of time.

Cooling the suppressor also provides improved noise and lifetime performance. A temperature setting of 20˚C for the thermal compartment, such as the DC, is recommended.

The optimum current setting depends on the following:

  • Eluent concentration
  • Sample counterion concentration
  • Flow rate
  • Mode of operation

If the sample counterion concentration exceeds the eluent concentration, use the sample counterion concentration in the calculation discussed below. These calculations are specific for the type of suppressor. These settings are also applicable in the presence of standard solvents such as methanol or isopropyl alcohol for anion applications and acetonitrile for cation applications.

NOTE

When operated in Neutralization Mode, the Dionex DRS 600 current should always be set to 500 mA.

Current (mA) = FlowRate (mL/min) × [Eluent] × Suppressor Specific Factor

The factors are listed in the table below. The unit for eluent concentration is mN (not mM).

Optimum Suppressor Settings

Suppressor Type

Suppressor Specific Factor

Dionex ADRS 600 (Legacy Mode) and Dionex AERS 500e

2.47

Dionex CDRS 600 (Legacy Mode) and Dionex CERS 500e

2.94

Dionex AERS 500 Carbonate

3.22

NOTE

Always round the calculated optimum current up to the nearest whole integer.

All modern Thermo Scientific Dionex detectors and suppressor power supplies can be used to set the current at the calculated value with a minimum current resolution of 1 mA. A Dionex RFC-10 or Dionex RFC-30 is required for older systems that only set the current in discrete values of 50, 100, 300 or 500 mA.

NOTE

A lower flow rate requires a lower current. A 2 mm Dionex DRS 600 or Dionex ERS 500e should never be operated at a current above 150 mA. A 2 mm Dionex AERS 500 Carbonate should never be operated at a current above 30 mA.

NOTE

Chromeleon 7.2 SR3 MUa and later have an option for selecting an AERS_Carbonate suppressor in the Instrument Method Wizard and Editor dialog box. Selecting this suppressor from the drop-down list will automatically apply the recommended current setting for the Dionex AERS 500 Carbonate suppressors. Earlier versions of Chromeleon do not include the correct Suppressor Specific Factor; therefore, the correct current must be calculated and entered manually if the Dionex AERS 500 Carbonate suppressor is use.

The maximum suppression capacity (MSC) depends on the eluent concentration and flow rate. The MSC can be calculated using the following equation.

MSC (mN * mL/min) = flow rate (mL/min) * sum of eluent concentration (mN)

Maximum Suppression Capacity for Dionex DRS 600, Dionex ERS 500e and Dionex AERS 500 Carbonate suppressors

Suppressor

Flow Rate (mL/min)

Max. Suppression Capacity

Dionex ADRS 600 (4 mm)
Dionex AERS 500e (4 mm)

0.5 – 3.0

≤ 200 μeq.

Dionex AERS 500 Carbonate (4 mm)

0.5 – 3.0

≤ 30 μeq.

Dionex ADRS 600 (2 mm)
Dionex AERS 500e (2 mm)

0.25 – 0.75

≤ 50 μeq.

Dionex AERS 500 Carbonate (2 mm)

0.5 – 3.0

≤ 7.5 μeq.

Dionex ADRS 600 (2 mm)
Dionex AERS 500e (2 mm)

0.10 – 0.25

≤ 30 μeq.

Dionex CDRS 600 (4 mm)
Dionex CERS 500e (4 mm)

0.5 – 3.0

≤ 100 μeq.

Dionex CDRS 600 (2 mm)
Dionex CERS 500e (2 mm)

0.25 – 0.75

≤ 35 μeq.

Dionex CDRS 600 (2 mm)
Dionex CERS 500e (2 mm)

0.10 – 0.25

≤ 20 μeq.

When using a Dionex ADRS 600, Dionex AERS 500e or Dionex AERS 500 Carbonate, the sum of the eluent concentration can be calculated from the equations below.

Sum of eluent concentration

Suppressor

Eluent concentration equation

Dionex ADRS 500 (4 mm)
Dionex AERS 500e (2 mm)
Dionex AERS 500 Carbonate (4 mm)

Sum of eluent concentration (mN) = {2* Carbonate (mM) + Bicarbonate (mM) + hydroxide (mM) + 2 * Tetraborate (mM) + custom eluent cation (mN)}

where Tetraborate is <= 50 mM

Dionex AERS 500 (2 mm)
Dionex AERS 500e (2 mm)
Dionex AERS 500 Carbonate (2 mm)

Sum of eluent concentration (mN) = {2 * Carbonate (mM) + Bicarbonate (mM) + hydroxide (mM) + 2 * Tetraborate (mM) + custom eluent cation (mN)}

where Tetraborate is <= 75 mM

Custom eluent cation (mN) can be calculated from the normality1) of the eluent concentration.

Dionex CERS 500

Sum of eluent concentration (mN) ={2 * Sulfuric Acid (mM) + MSA (mM) + custom eluent anion (mN)}

Custom eluent anion (mN) can be calculated from the normality2) of the eluent concentration.