Chromatography Forum

allo. I have a few models of old GC and I would like to know if I can modify them for Capillary columns usage. Models are:
#1-- HP 5730A dual ports with dual differential electrometer/FID control,
#2-- HP 5710A dual ports with TCD detection
#3-- HP 5720A single port in usage, FID detection
#4 -- Varian 3700, dual ports (also autosampler), with differential electrometer/FID
among all those, is there a possibility to modify? if so, what would be my best choice? I am looking for a very reliable, accurate and reproducible method which will mostly be used for FAME analysis. Thanks

Supelco and Alltech (Grace Davison) used to have conversion kits to install megabore capillary columns in Dual FID GCs.

Contact their technical services and inquire.

best wishes,

Rod

The Varian 3700 was available as a capillary instrument, with front pressure regulation and a split valve in the hot injection block. I have fond memories.

If you are comfortable with making your own gas plumbing, and handy with Swageloks and some simple metalwork you can probably convert all of these to capillary. You can use the existing mass flow controller for the carrier gas to control make-up gas to the detector, and add a pressure regulator to control carrier gas head pressure. A needle valve will serve for the splitter. Needless to say you will not be running in constant flow mode !

There may be some issues with the response time of the old electrometers being too slow for narrow capillary GC peaks.

Good luck with it !

Peter

What country are you in?

What century are you in?

CPG,

Now now

l2descha must live near a GC graveyard. Waste not, want not.

True, 5730 was a dead model 30 years ago !

And I learned GC on a 3700 over 30 years ago.

Perhaps he found a time tunnel.

I want to go back l2descha. Take me. Take me.

Rod

mmm half inch fittings, rotamers if you are lucky, and analog electronics - fun for a hobbyist anyhow. Good Luck!

What country are you in?

What century are you in?

OOps! I thought that was a GC forum

What country are you in?

What century are you in?

OOps! I thought that was a GC forum

It is !!! But trying to modify/adapt long-obsolete equipment is not typically the most cost-effective solution. Parts and labor (even your labor) need to be considered.

OK, back to business. FAME analysis can be easy/straightforward such as for bar soap coconut and tallow fatty acids which range from C8 to C18 and can be done fine on a Supelco SP-2330 packed column, or be way involved like for butter, fish oils, etc., for which capillary is needed, and 0.53mm "megabore" columns likely won't suffice for those.

FAME analysis in what?

The Varian 3700 was available as a capillary instrument, with front pressure regulation and a split valve in the hot injection block. I have fond memories.

If you are comfortable with making your own gas plumbing, and handy with Swageloks and some simple metalwork you can probably convert all of these to capillary. You can use the existing mass flow controller for the carrier gas to control make-up gas to the detector, and add a pressure regulator to control carrier gas head pressure. A needle valve will serve for the splitter. Needless to say you will not be running in constant flow mode !

There may be some issues with the response time of the old electrometers being too slow for narrow capillary GC peaks.

Good luck with it !

Peter

thanks Peter. I guess my best choice would be Varian 3700. I found a manual and info on the web. I sure will give it a try. thanks for the tips

l2descha,

If it were me, I would use the 3700 and I would buy an inlet modifying kit (from Alltech for example) that allowed me to plug a 0.53 capillary column directly into a restriction in an inlet liner installed in a packed port. That's how I started out when I first started on my own. A 0.53 can handle packed flows and will give you reasonably pretty chromatography in this situation especially if you are well away from the solvent front. If you are operating near the solvent front, spend some money to buy a 5890 with a splitless/split inlet.

Best regards,

AICMM

I'd just buy a 5890. Those things are floating around for cheap and are infinitely more modern than the instruments the OP is considering using.

Depending on where in the world you are it must surely be much cheaper and easier to get a capillary GC. You mention reliable , 30 + year old GCS are not generally considered reliable and with "heath robinson" additions !

You should be able to get a functioning but basic split/splitless GC for about the cost of a GC column, don't waste time and money on the GCS you have.