How to perform a solvent changeover procedure on Waters Styragel columns to convert from THF to DCM (dichloromethane, methylene chloride) - WKB116479

OBJECTIVE or GOAL

Convert Styragel columns packed in tetrahydrofuran (THF) to dichloromethane (DCM) (also called methylene chloride).

ENVIRONMENT

• Gel permeation chromatography (GPC)
• Styragel columns
• Solvent changeover

PROCEDURE

1. Set the column oven to 20 °C.
2. For 7.8 x 300 mm columns, set the pump flow rate to 0.1 mL/min throughout this procedure.
   • For 6.0 x 150 mm columns, use 0.06 mL/min throughout this procedure.
   • For 4.6 x 300 mm columns, use 0.03 mL/min throughout this procedure.
3. If you are running a gradient, program a 95:5 THF:DCM to 100% DCM, over four hours.
   • If you are running in isocratic mode, make separate THF:DCM solutions in 5% steps from 95:5 THF:DCM to 100% DCM, and increase DCM strength over four hours.
4. Flush with 100% DCM for 6 hours per column. 
   • If there are two columns in the column bank, flush for a total of twelve hours. 
   • This equates to 10 column volumes per column.
5. This solvent switch should only be performed once in the column's lifetime.

ADDITIONAL INFORMATION

GPC Columns –  General Operating Procedures when not performing solvent switch:

• Always ramp from 0.1 mL/min to approximately 1 mL/min over five minutes, for 7.8 x 300 mm columns, for example.
• Do likewise when ramping down flow rate.
• Typical operating flow rates when performing GPC separations on Styragel columns:
  • 7.8 x 300 mm columns  -  1.0 mL/min
  • 6.0 x 150 mm columns  -  0.6 mL/min
  • 4.6 x 300 mm columns  -  0.3 mL/min
• When the column is not in use but is kept on a system, keep the flow rate at 0.1 mL/min minimum at all times. Do not power-off the pump.