During storage or shipment, the Dionex ERD 500 might become dehydrated. Since effective desalting requires fully hydrated membranes, the Dionex ERD 500 must be rehydrated prior to use.

Procedure

  1. Set up and plumb the regenerant in and out tubing as described in Recommended conditions. Supply regenerant (e.g., 150 mM TFA) through the Dionex ERD 500 at approximately 5 mL/min for 4 mm and 1 mL/min for 2 mm by adjusting the pressure regulator to the regenerant reservoir to 10–15 psi, and until no bubbles are observed exiting the Dionex ERD 500 (typically about 5 minutes).
  2. Stop the flow, and let the Dionex ERD 500 stand, with regenerant in its chambers, for at least 20 minutes.
  3. Connect the eluent tubing from the pulsed amperometric detector to the ELUENT IN port on the Dionex ERD 500, and connect the fraction collector tubing to the ELUENT OUT port on the Dionex ERD 500. See the following figure.
  4. Configuration of the Dionex ERD 500 in an HPAEC/PAD System
    Configuration of the Dionex ERD 500 in an HPAEC/PAD System
  5. Restart the regenerant flow and adjust to ≥ 7 mL/min for 4mm and ≥ 2 mL/min for 2 mm by applying approximately 4–25 PSI to the regenerant reservoir (measure this flow to be at least 7 mL/min for 4 mm and 2 mL/min for 2 mm).
  6. NOTE

    A direct reading flowmeter to ensure proper regenerant flow may be placed between the regenerant reservoir and the REGEN IN port on the Dionex ERD 500 (e.g. a Gilmont (Barrington, IL) GF2200 flowmeter with glass float reads from ~ 0.4 to ~ 40 mL/min).

  7. The Dionex RFC-10 supplies power to the Dionex ERD 500 for electrolytic generation of hydronium ions.
  8. Connect the Dionex RFC-10 to the Dionex ERD 500 with the attached electrical cable. Plug the Dionex RFC-10 into an appropriate AC supply.
  9. Turn on the Dionex RFC-10 and set current to 50 mA.
  10. The green LED shows when the Dionex ERD 500 is ready. The green light indicates that the power is on, the Dionex ERD 500 is connected to the Dionex RFC-10, and that the conductive regenerant needed is flowing in the regenerant chambers. If the green light fails to glow, double check these conditions.
  11. When the green LED is illuminated, set current to 500 mA for 4 mm or 125 mA for 2 mm.
  12. Increase the pressure on the regenerant reservoir to reestablish a regenerant flow of 7 mL/min for 4 mm or 2 mL/min for 2 mm through the regenerant chambers. Note that the application of power from the Dionex RFC-10 will cause bubble formation within the Dionex ERD 500. The bubbles will restrict regenerant flow, so additional pressure must be applied to maintain the regenerant flow needed to desalt the eluents used during oligosaccharide chromatography.
  13. Start the eluent pump to begin flow through the Dionex ERD 500 at ≤1.0 mL/min for 4 mm or ≤ 0.25 mL/min for 2 mm, and allow the system to equilibrate under these conditions for at least 25 minutes. Before injecting a sample, pH indicating paper may be used to check that the pH of the Dionex ERD 500 effluent is ≤ 6, and is stable.