ShinCarbon columns - Installation / Conditioning / Helpful Hints26 Sep 2012
For those of you who may be interested in using a ShinCarbon for the first time, I’ll walk you through the process of getting your new column ready for analysis. Even though we take great care to minimize the time you will need to condition your column after you receive it, please remember, this packing, like all molecular sieves, likes to absorb everything it is exposed to, so any column will need some conditioning after you receive it. For additional information, see “Molecular Sieve Packed Columns and Fixed (Permanent) Gas Analysis“.
Following the steps below will ensure that your column is ready to use just several hours after installation.
1. Cool all heated zones and then turn-off all GC gases. Please allow the current packed column (if one is installed) to depressurize so that its removal from the GC (more specifically, the inlet) doesn’t cause a pressure surge which can cause expel packing from the column (see Helpful Hints C below for additional information).
2. Molecular sieve columns are commonly end capped to prevent moisture diffusion. Remove the column end caps (and silicone ferrule, if present) and attach the appropriate nut & ferrule to the inlet side of the column.
Install the new ShinCarbon into the injection port. Do not connect to the detector at this time. Do not turn on any heated zones. Slowly increase the head-pressure just until carrier gas flow starts exiting from the column.
3. 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*, continue to monitor the exiting carrier gas flow rate for five minutes to make sure it is stable.
4. Remove the flow meter and purge the column for an additional 10 minutes to remove all traces of air. Set the GC oven temperature to 40⁰C and program the oven to ramp at 5°C/min to 275°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 packing (300°C). Begin the GC oven program ramp. When 275°C is reached, hold it at this temperature for 3 hours.
5. Cool the GC oven (do not turn off the carrier gas). Install the column into the detector and heat the detector to the desired temperature, but do not expose the column to higher temperatures than the maximum temperature of the packing (280°C).
6. Your column should be ready to use.
Restek ProFLOW 6000 Electronic Flowmeter
A. If you notice any degradation with the chromatography, you may need to “dry” the column. To do so, increase the GC oven to 250⁰C and hold for 30 minutes. This should remove all traces of water vapor.
If you experience a decrease in response for the oxygen peak, but the carbon monoxide peak does not tail, the problem may be with the pre-column (stripper column), especially if this pre-column is a porous polymer..
B. Always use high quality gas traps/filters on your carrier gas line. As mentioned earlier, molecular sieve packings like to absorb everything.
C. Never perform any GC maintenance (such as replacing the septum or liner) or remove a packed/micropacked column from a GC, without having the carrier gas turned-off and allowing the column/instrument to depressurize. Otherwise the packed column’s bed may collapse or particles may be expelled.
D. If the column is not going to be used for several days, all the instrument’s heated zones should be cooled and the carrier gas turned off. The column should be removed and the ends should be capped to keep air/moisture out of the column. If the column is going to be used the following day, do not cool instrument’s heated zones, leave the carrier gas on, and set the GC oven temperature to 150°C.
E. When using a high sensitivity detector like a HID, DID, FID, etc… a micropacked column (0.53mmID through 1.0mmID) should work well. However, when using a low sensitivity detector like a TCD, consider using a 2.0mmID (1/8”OD) packed column (for capacity).
F. Carbon molecular sieve columns are extremely retentive. Ideally, compounds larger than C5 (pentane), or compounds with a boiling point greater than 50°C, should not be injected onto these columns. If you suspect your samples may contain “heavies”, consider using a system which incorporates a pre-column and valve switching link.
Ideally, only compounds which are gases at room temperature should be injected onto these columns.
G. If you need help installing a column, you may want to contact your instrument manufacturer.
Common carrier gas flow rates for conditioning packed/micropacked columns:
0.53mmID (0.74mmOD) = 5mL/min
0.75mmID (0.95mmOD) = 7.5mL/min
1.0mmID (1/16”OD) = 10mL/min
2.0mmID (1/8” OD) = 20mL/min.
Safety Note: If using hydrogen as the carrier gas, please safely vent the hydrogen during the conditioning process. Do Not vent the gas into a confined space, like the GC oven.