Chromatography Forum

Hi there..

Actually, i am working in LPG company, we have two products Propane and Butane.

We are running two GC methods using Varian CP-3800 GCs for composition, at this point we are looking to modify the methods what we have in term of opimizing the run time as well as the separation.

I would ask if any could provide me with any reference methods already undertaken by any party.

All the best

There are standard methods, refer to the US-based NGPA documents for LPG etc, and also ASTM D2163-07 ( they withdrew the earlier version, then reinstated. I'm not sure if there are substantive differences between them ).

Given the range of automated calculations ( eg energy content ) that usually derive from the GC analysis of liquified hydrocarbon fuel gases, some care is needed to ensure that GC method changes don't affect the accuracy of such derived data.

Virtually every major manufacturer of GCs will have guides/technical support on the best methods of reducing analysis time, so I'd start by talking to them - to capture what is known.

Please keep having fun,

Bruce Hamilton

Generally, you should expect to look for olefins and for hydrocarbons that are one carbon larger and smaller than the balance of your sample.

for propane:

ethane, ethylene, propylene, isobutane, butane, 1-butene, isobutylene, and perhaps, cyclopropane.

for butane:

propane, propylene, isobutane, 1-butene, 2-butenes, isopentane, pentane, and pentenes.

The fastest applications will use multidimensional chromatography and packed columns. Scot columns could also perform the applications quickly.

You can order standard tests from GPA or ASTM authorities. You can also develop your own methods. There are companies that will sell you methods and column sets for a relatively minor fee of several thousand dollars. It will depend upon your customers to accept your methods. You may wish to use methods that they will accept as valid.

Varian sells dedicated instruments and has methods you should consider.

Discuss this with your management and decide which course you wish to follow.

best wishes,

Rod

Alchemist,

Tell us more about what you want if you please. Are you looking to do better separations (like olefins from paraffins) or more willing to smash things together for the shorter run time. Do you know what columns you are currently using, what detector, what injector, how long is your current run... The more info you provide the more support we can provide.

Best regards.

Thanx to all,

I would like to thank you all about your corporation.

Acutally, the current methods used for LPG as well as Gases are almost old, my supervisor's style is little bit old and he resists the change.

I was thinking to optimize the current methods.

I am looking for pevious experience with CP-3800 varian GCs, currently i doing the optimization by playing with the temp programming and the same time try to do some trials with pressure and split ratio.

Any recommendation, references that may help or already carried out methods for the same application.

Regrads,
Alchemist