Chromatography Forum

Hello Friends,

I've recently purchased a 1/8" ID packed column to hookup to a 5890 with a capillary injection port and FID. After doing some research, it seems like the best way of doing this will be to pigtail a capillary guard column with the packed column. This seems to be a fairly cheep and simple solution but my question is will this setup require a changing of the instrument conditions, for the analysis I had planned on performing? For example, where the test method asks for a 0.5ul injection, will i need to change this injection volume because of this setup. The only possible change I could assume, will occur with the column pressure.

If you've done a pigtail before or may offer any insight, I will appreciate it.

Thank you in advance

The pigtail setup sounds unusual. I can imagine several issues -- it may be difficult to get a high enough flow, but perhaps with a .53mm guard/transition column and enough pressure it would be ok. Another issue is, as you hinted at, sample amounts. Also, you'll be introducing more adapters and fittings that eventually tend to degrade the quality of the chromatography, whether due to active sites or discrimination or dead volume or eddying.

Do you know if your FID is a capillary only type or a cap/packed type? If it is compatible with packed columns that eliminates a host of other problems...

Your question about changing instrument conditions: yes absolutely you will need to adjust the instrument parameters.

I've done this on a 5890. There are 1/4 inch diameter packed column adapters that screw in to the capillary inlet and FID ports, should be same as on a 6890, likely still available new, if not contact me.

The GC I used was not EPC, so I capped off the split vent and septum vent outlets on the front of the GC. I adjusted pressure to about 20-30 psi and measured flow with a flow meter.

If EPC controlled, maybe can just set those settings to zero.

KM is on the right track but I would add one thing (a clarification?) to his comments. I don't believe the S/S inlet can take 1/4" packed (at least none of mine can) so I would take a short piece of megabore (0.53) as the transfer line between the inlet and the head of the column. Otherwise, capping split and septum purge advice is right on the money.

Best regards,

AICMM

Thank you for your comments. I am going to set up this GC in the next two week, I will keep you all posted.

KM is on the right track but I would add one thing (a clarification?) to his comments. I don't believe the S/S inlet can take 1/4" packed (at least none of mine can) so I would take a short piece of megabore (0.53) as the transfer line between the inlet and the head of the column. Otherwise, capping split and septum purge advice is right on the money.

The stainless steel liners for packed columns is 1/4 inch o.d., both the one for 1/8 and for 1/4 inch columns. Or if the end of the 1/4 inch columns have no swaged ferrules/nuts on the inlet end, the inlet end of the column can be pushed up and secured with the O-ring, right?