Separation of CF2Cl-CF2-CCl2F and CF3-CF2-CCl3

[Chandresh K. Soni]

CAn we Analyse both compound on DB-624 Column.
I got Small Shoulder and can't separate these compound on one another. please suggest suitable GC Capillary Column.
we also tried it on HP-5, Cpsil 5CB,

we have the GC capillary column HP-1 , HP-5 , DB-Wax , DB1301, DB - 624

[chromatographer1]

It is highly unlikely that any capillary column on the market with the possible exception of the Gaspro will separate these two gases. I suggest you go to your supplier for answers, or try technical service from a Freon supplier to get your answer.

A 10 meter packed column of Carbopack B with one of two liquid phases may separate them. Call Supelco or email their techservice dept for assistance.

Rod

[chromatographer1]

Here are 6m, and (2x6m =) 12m packed columns that are useful for freons besides the 10m columns I mentioned previously which unlike these are available with screen terminations instead of glass wool.

13271-U copper, phase 5% Krytox 143AC, matrix 60/80 Carbopack B, 3 in. coil (Supelco)
13273-U copper, phase 5% Krytox 143AC, matrix 60/80 Carbopack B, 3 in. coil (Supelco)
13274-U copper, phase 30% Krytox 143AC, matrix 60/80 Chromosorb PNAW, 3 in. coil (Supelco)
13277-U copper, phase 30% Krytox 143AC, matrix 60/80 Chromosorb PNAW, 3 in. coil (Supelco)

Rod

[Karen01]

I've used a 60/80 Carboblack-B / 5% Krytox 3.05 m x 2.1 mm from Restek for doing perfluoropropane and perfluorobutane.

It may be possible to do on a capillary column BUT it's not easy nor convenient and not great chromatographically. At the time (many years ago) I knew about the above packed column as it was the only one I could find for such compounds, but the GC I was using did not have a packed inlet so I figured out a way to do it with a capillary column.

I used a PLOT column and subambient temperatures to do the above compounds by GC/FID... I was probably condensing the perfluorocarbons at the head of the column and then boiling them off with the temperature ramp.

I don't recommend doing that ... Save yourself a lot of trouble and use one of the packed columns meant for freons, even if you have to get a packed inlet installed to do it.... that is what I SHOULD have done at the beginning many years ago.

- Karen

[Chandresh K. Soni]

Thanks, Chromatographer and Karen for your Valuable Suggestion.
I think Both the Compound Mixture have the Boiling Point of 73°C and also the Compound Have the Little % of CCl4.
So these compound is not in GAS Phase ( they are in Liquid Phase) and Is it Suitable to Analyse this liquid on GASPRO Column , B' use i have the GASPRO CApillary Column.

I want to analyse on CApillary Column.

pls Suggest me

[chromatographer1]

well, give the Gaspro a shot.

You have to realize that boiling point and dipole separation mechanisms are not suitable for these analytes. That gives you size inclusion and pi bond attraction mechanisms as alternatives. Pick your column. If you know of any other capillary columns other than plot porous polymer or porous glass beads be sure to post it on the forum. I would love to know about it.

To bad you can't keep an old packed column GC around with a TCD and FID detector. Sometimes you don't need a razor but an ax to get the job done.

best wishes,

Rod

[Chandresh K. Soni]

We Have only GAspro , DB-1301 , DB-624 , HP-5 , CPSIL 5CB , DB-200 columns in Capillary.
We Also Have the PAcked Column with Porapak Series.

I also Doubtfull about The GAspro as u suggest Is Stationary Phase is Suitable For CCl4 and For Both These Liquid

Thanks

[chromatographer1]

I offered Gaspro only as an UNKNOWN alternative. It has a porous composition and thus could, MIGHT be a solution. You might try a chiral column but I would not know where to start in making a suggestion.

You seem to be suggesting that chlorinated or non-polar liquids are not suited for the Gaspro column. Is this true or is my conclusion unfounded?

I believe that a packed column is your only hope for a full resolution of the two analytes. Besides the Kyrtox 143 AB or AC phase on Chromosorb P or Carbopack B, 1% Cwax 20m on Carbopack B is also an alternative that has proven to be useful in separating freons.

You can try Alltech, Restek, and Supelco service to see if they have something to help you.

best wishes,

Rod

[Chandresh K. Soni]

Thanks ROD,
Your Conclusion is Right REgarding my Doubt. But Lets See What Happen if We Inject 0.1µl Sample on GASPRO PHASE.
I am also want to Go for techincal Support or Chiral Column but this is the Last Option for me.

Again Thanks For Your Support and What is the Consequence i will surely share with you.

Chandresh

[chromatographer1]

"Again Thanks For Your Support and What is the Consequence i will surely share with you.

Chandresh"

Have you found any consequences yet?

Any progress on finding a solution?

best wishes,

Rod

[Chandresh K. Soni]

Dear ROD,
I injected the Sample on GAspro Column but we were not found the separation on these compound . alco due to some limitations w eare not able to do more work at this time. but i am sure we can do it on DB-624 , 60meter b'use on this column we got some shoulder with main peak so if we will tried it with flow and temp. ramp we may be able to got the separation.
thanks for remembering me the pending work.

regards
chandresh

[chromatographer1]

I forcast failure with the 624 column but I wish you success.

best wishes,

Rod

[aldehyde]

Question for Karen and and chromatographer1, is there a book or other resource you would recommend for assisting with column selection? I always feel a bit befuddled when it comes to recommending a column for a specific analysis.

And Karen, its great to have you on the site. I've noticed a few really good comments from you already, thanks!

[chromatographer1]

McRenyolds and others in the early days of GC published data for the separation of the most popular analytes from those days.

With the advent of capillary columns the need for selectivity was reduced with the increased number of theoretical plates available in a 60 meter column. Most separations were accomplished by sheer 'boiling point' mechanisms.

Induced dipole, dipole, and other mechanisms were ignored for the most part by analysts and as well as their proper application for the separation of two analytes.

Experience and a little book-learning will guide most analysts to a good guess for a proper choice in column selection. Sadly broad analyte experience is usually lacking in most chromatography jobs today. But the good news is there is a lot of literature available to help you that has been published in the last 50 years.

And so many chromatographers hate to give their names and location to the chromatography supply companies, yet by doing so miss out in the FREE information and assistance that they FREELY offer to their potential customers, companies like Supelco and Restek et al.

Having used Supelco's technical service in several jobs prior to being employed there until a few years ago, I can witness to the savings of time and money merely by asking a few questions to a knowledgeable scientist on the other end of the phone, or via email.

Supelco and Alltech were pillars of chromatography when packed columns were the norm. Restek which was founded by a Supelco employee continued the tradition of supplying technical information freely in the decades of capillary columns.

Sigma Chemical, the parent corporation of Supelco, provides chemicals of a broad spectrum to researchers and has an enormous amount of chromatography information that is often available to customers, separately from Supelco itself.

Use the free resources available today. Use libraries or buy the journals that may be useful to you in your job.

The information is out there.

best wishes,

Rod

[Karen01]

What I do is use a little knowledge of the partitioning mechanisms and look through vendor catalogs. There is a wealth of information about columns and separations and examples for different classes of compounds to be found in catalogs...

That's how I've learned a lot over the years. When I found column I also madse sure i thought I understood WHY it worked.

As for catalogs I thnk that paper is much better than electronic when you don't know exactly what you are looking for. Unfortunately with all the acquisitions there are not as many different catalogs as there once were.

- Karen