The following steps will ensure that your packed or micropacked column is ready to use just a few hours after installation. Be sure to use only dry (no moisture) high-purity carrier gas to condition your column. In addition, quality gas traps are strongly recommended.
- Cool all heated zones in your GC, and then turn off all GC gases. If a column is installed, allow both the column and the instrument to depressurize before proceeding.
Caution: Removing a packed or micropacked column from the GC (or more specifically, the inlet) before it depressurizes can cause a pressure surge capable of expelling packing from the column. Depressurizing before all heated zones in your GC are cool can also damage your column. - Install your new packed or micropacked column into the injection port. Do not connect the column to the detector at this time; instead, cap the detector. Do not turn on any heated zones.
- Slowly increase the head-pressure just until carrier gas flow starts exiting from the column.
- Attach an electronic flow meter (or soap-bubble flow meter) to the outlet of the column and once again begin to slowly increase the head-pressure. When the desired column flow rate has been obtained (see Table I for common column conditioning flow rates) continue to monitor the exiting carrier gas flow rate for five minutes to make sure it is stable.
Warning: If you are using hydrogen as your carrier gas, you must either safely vent the open end of your column out of the oven to prevent hydrogen buildup, or safely vent the hydrogen gas from a non-destructive detector (like a TCD) in order to minimize the potential of an explosion. If using a destructive detector like a FID, make sure the flame is lit. Note: never connect a flowmeter to a lit FID or a heated detector.
| Column Dimensions | Flow Rate |
| 0.53 mm ID (0.74 mm OD) | 5 mL/min |
| 0.75 mm ID (0.95 mm OD) | 7.5 mL/min |
| 1 mm ID (1/16” OD) | 10 mL/min |
| 2 mm ID (1/8” OD) | 20 mL/min |
| 3.1 mm ID (3/16” OD) | 30 mL/min |
Table I: Common conditioning carrier gas flow rates for packed and micropacked columns.
- Disconnect the flowmeter, and purge the column for an additional ten minutes to remove all traces of air. Set the GC oven temperature to 100 °C. Heat the GC injection port (if applicable) to the desired temperature, but do not expose the column to higher temperatures than the maximum temperature of the column. Program the oven to ramp at 5 °C/min to 20 °C below the column’s maximum temperature, and begin heating GC oven. When the appropriate temperature is reached (20 °C below the column’s maximum temperature), hold at this temperature for one hour (except for the packings listed below).
For solid supports with liquid phase loadings >10%: Hold for two hours.
For molecular sieves: Hold for three hours. (Conditioning with high-purity dry nitrogen is also recommended.) - Cool the GC oven, but do not turn off the carrier gas. Install the column into the detector. Heat the detector to the desired temperature, but do not expose the column to higher temperatures than the maximum temperature of the column.
- Your column is conditioned and ready to use.
Column Conditioning Helpful Hints:
- Never perform GC maintenance (even just replacing a septum or liner) and never remove a packed or micropacked column from the GC without A) cooling all heated zones in your GC, B) turning all GC gases off, and C) allowing both the column and the instrument to depressurize. If you fail to do these things, the column’s bed may collapse, particles may be expelled from the column, or the column may be otherwise damaged.
- If the column will not be used for more than one week, the column should be cooled and the carrier gas turned off. If the carrier gas is left on, make sure the oven remains set to 100 °C to keep moisture (water) from condensing inside the column.
- A micropacked column (0.53 mm ID through 1 mm ID) should work well with high-sensitivity detectors like HID, DID, FID, etc. However, when using a low-sensitivity detector like a TCD, consider using a 2 mm ID (1/8” OD) packed column for higher capacity.
