Stationary Phase Equivalences

[marinamax2000]

Hi everyone!

I have recently changed the old packed column CG for a capilar column one, and trying to find the equivalences of stationary phase composition... Does anyone happen to know some information source about equivalences between different brand columns?
We used to work with OV-17, Hayesep N 80/100 and Porapack N80/100 the last two for the determination of ethylene anc acetylene.

Thanks in advance,

[chromatographer1]

There are many manufacturers who make 50% Phenyl 50% methyl silicone phase capillaries, the equivalent of OV-17.

My company Supelco calls their three equivalent capillary column phases, SP-2250, SPB-50, and SPB-17, the latter two are bonded and may be rinsed. Slight differences may be noted with certain analytes but these are considered G3 type phases by the USP.

Porapak N and Hayesep N are similar porous polymer columns and due to the fact that some means of bonding the beads to the capillary wall surface must be used there may be slight differences in selectivity. In fact there are often slight differences in selectivity of different lots of beads used in packed columns. Usually these are not noteworthy and rarely cause problems of even the most minor nature.

If speed of analysis is the motivation with changing from a packed porous polymer column to a capillary column I must tell you I believe that you will not gain much if anything going to a capillary column in most cases.

Instead use micropacked columns and you will find you still have a large sample capacity which is quite handy when using a TCD detector and you will shorten your analysis time, often by half.

They may be used in a split mode if desired or directly using a much smaller sample size and flow rate, 100µL and 5cc/min for example, but to gain speed a higher flow can be used, 20cc/min. for example.

If you still intend to use capillary PLOT porous polymer columns several manufacturers use a newer formulation for N using divinylbenzene and ethyleneglycol methacrylate polymer in their PLOT capillary columns. This may also be called A or U polymer as well as N. There may be selectivity changes to the historical selectivity of Porapak N. You should check with the vendor to determine if your requirements are met by their columns.

best wishes,

Rodney George
Senior Research and Development Scientist
Gas Separations Research
Supelco
595 North Harrison Road
Bellefonte, PA 16823

814-359-5737 voice
814-359-5459 fax
rodney.george@sial.com

[marinamax2000]

Dear Rodney:

Thanks for your kind and prompt reply:
the motivation for the change is that we have bought a new CG and as most new techniques come for capillary columns, and we had to buy two inyectors to use capillary and packed columns, we decided to switch to capillary ones.
The micropacked columns ¿can be used with the same fittings as capillar ones?
I´m looking for a column that will separate ethylene from acetylene, and found that VP-alumina ones could be the solution...
I also found this piece of onfo:
1- Hayesep N seems to have a Divinylbenzene/ethyleneglycoldimethacrylate stationary phase
2- Porapack N seems to have a 20% ethyl N, N – dimethyloxolamide stationary phase, but I´m not very sure about the other 80%...

If you can give me some URL where to find info about stationary phase equivalences, I will be grateful......

Thanks,

[chromatographer1]

Examine capillary column company web sites for the information you seek.

My company is www.sial.com/Supelco

Here are other companies:

Agilent

Varian

Restek

SGE

VICI

Quadrex

Use Google.com and perfrom a search and you will find even more.

Porapak N originally used a formulation containing copolymers like the R polymer: DVB and 2VP.

I hope your new GC has a detector that will allow you to measure at the same levels that equal your old packed column TCD. If you are only measuring hydrocarbons then an FID should be adequate.

To separate acetylene from ethylene there are many choices.

I do not know of any deactivated alumina columns that will not separate acetylene from ethylene. Getting a quantitative recovery of acetylene is another but critical parameter you should consider when trying to measure low levels of acetylene with alumina columns.

A Carboxen PLOT capillary will also perform this separation with acetylene eluting BEFORE ethylene and ethane.

S and T polymers will separate acetylene, as will the U polymer.

If you have any other questions feel free to email technical service at Supelco.

best wishes,

Rod