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- Posts: 15
- Joined: Fri Sep 03, 2004 5:39 pm
What has worked for our lab is the following (I've only been doing GC work for just over a year now):
Cut retention gap, wipe with acetone dampened kimwipe, apply a small dab of resin (Agilent PN: 500-1200) near the end of the column (a few mm), insert into the union and hold in place for 20-30 seconds.
Repeat with the column end. Once both sides are seated in the glass union, set the inlet and oven temps to method starting conditions, but keep the helium flow/pressure about 40% of it's starting condition (ie. if 100 kPa, set to 40 kPa) is for 30-60 minutes. Then increase the flow to normal operating levels.
We keep the resin at 4C when not being used, and let warm to room temp before applying.
This has provided for reliable seals using glass unions. Another thing of note. We were using Agilent Universal glass unions, PN: 705-0825, and even though the part number is the same, the most recent batch we got was physically different. The current ones have "fluted" ends and if you place a .530mm fused silica retention gap in one end, it seats 9mm inside from one end and only 5mm from the other end, and the earlier ones were "flat" on the ends and the RG seated ~8mm from either end.
Where this distance became an issue is if you do add the resin, you have to make sure it's close enough to the end of the RG to also "stick" to the union by making contact. If it's too far from the end of the RG, it may not come in contact with the glass union and form as good of a seal (if any).
Just saw this post, so my answer may be a bit late.
Cut retention gap, wipe with acetone dampened kimwipe, apply a small dab of resin (Agilent PN: 500-1200) near the end of the column (a few mm), insert into the union and hold in place for 20-30 seconds.
Repeat with the column end. Once both sides are seated in the glass union, set the inlet and oven temps to method starting conditions, but keep the helium flow/pressure about 40% of it's starting condition (ie. if 100 kPa, set to 40 kPa) is for 30-60 minutes. Then increase the flow to normal operating levels.
We keep the resin at 4C when not being used, and let warm to room temp before applying.
This has provided for reliable seals using glass unions. Another thing of note. We were using Agilent Universal glass unions, PN: 705-0825, and even though the part number is the same, the most recent batch we got was physically different. The current ones have "fluted" ends and if you place a .530mm fused silica retention gap in one end, it seats 9mm inside from one end and only 5mm from the other end, and the earlier ones were "flat" on the ends and the RG seated ~8mm from either end.
Where this distance became an issue is if you do add the resin, you have to make sure it's close enough to the end of the RG to also "stick" to the union by making contact. If it's too far from the end of the RG, it may not come in contact with the glass union and form as good of a seal (if any).
Just saw this post, so my answer may be a bit late.
