Building Gas Chromatograph with Capillary Column: Tips & Guidelines

In summary: This person wants to build a gas chromatograph and has some questions about what would be a suitable stationary phase and what dimensions the column should be. They also have some doubts about whether or not aluminum would be a good material for the column.
  • #1
lilrex
64
0
I have a project that I want to do; really it is an experiment that would prove useful to another project of mine.

I want to build a gas chromatograph.

The specs.

Capillary column
Helium carrier
Thermal Conductivity Detector

The analyte is a mixture of CH4,N2 (for now)

I already have the TCD made and it is functioning well, I just need some info on the capillary.

Question: what will work well enough for a capillary column? Can I use a copper capillary as used for refrigeration? I know that the norm is a capillary that has a coating on the inside with a Stationary phase but will the walls of a copper or glass capillary suffice in this function? I suspect it all has do with the degree of separation that is needed but I am looking for some guidelines in this respect, just some empirical guidelines to help me get started.

Probably for one to make a recommendation I might give some more information I just need to make an approximation as to the quantity of the components in the anilyte, rarely would I even need to separate a complicated mixture just the simple one that I exemplified.

I guess that I could just buy some capillary and experiment but I just wanted your opinion on the matter.

Thanks, Cheers!
 
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  • #2
GC anaylisis of CH4

I mentioned in another thread that I wanted to build a Gas chromatograph but I think it was poorly stated so here are more specific questions.

I read that activated alumina is suitable to use as a stationary phase for the detection of hydrocarbons up to pentane, in the examples used the same column was used to separate the isotopes of hydrogen gas.

I am not sure exactly how this works, is it used as a kind of molecular sieve? or is it separating the mixtures by another means? I would like to know but more importantly I need someone with more experience then I that can tell me if activated alumina is capable of separating CH4 from N2 and O2 in a hydrogen or helium carrier?

I would like to use a capillary column but am having trouble selecting the right coating for this task.
 
  • #3
Al column

I am thinking about constructing the column out of aluminum, i figure that since the column packing is going to be AlO3 that it couldn’t hurt, of course I am not much of a chemist, but I can't think of any consequence to using the metal.

Normally for the packing one would use 30-120 grit closely separated material but all I have at the moment is 800 grit. So I will use a narrow tube, probably .67 mm in diameter. The problem I am seeing at this time is the dead space of the detector and will have to rebuild it, otherwise it will not resolve well. so if I am going to have any chance of a good measurement for my application I will guess that the dead volume of the detector needs to be 1% of the column,(if anyone else has an opinion on this, I appreciate advice)
 
  • #4
I really like projects like this as they teach you a lot if stuff!

cheers!
 

1. What is a gas chromatograph with a capillary column?

A gas chromatograph with a capillary column is an analytical instrument used to separate and analyze the components of a gaseous sample. It consists of a gas supply, injector, column, detector, and data recorder. The capillary column is a long, narrow tube with a thin film coating on the inner surface, allowing for efficient separation of the sample components.

2. How do I choose the right capillary column for my gas chromatograph?

The selection of the capillary column depends on the type of sample being analyzed and the components of interest. Factors such as column length, diameter, and type of stationary phase should be considered. It is recommended to consult with a column manufacturer or a chromatography expert for guidance in selecting the right column for your specific application.

3. What are some common troubleshooting tips for building a gas chromatograph with a capillary column?

Some common issues that may arise when building a gas chromatograph with a capillary column include leaks, column installation errors, and detector problems. To troubleshoot these issues, it is important to carefully follow the manufacturer's instructions, check for any leaks, and ensure proper installation of the column and detector. It is also recommended to regularly maintain and calibrate the instrument to ensure optimal performance.

4. How can I optimize the performance of my gas chromatograph with a capillary column?

To optimize the performance of your gas chromatograph with a capillary column, it is important to properly prepare and inject the sample, use the correct carrier gas flow rate, and ensure proper temperature control. It is also recommended to regularly clean and maintain the instrument and regularly replace the column and detector if necessary.

5. Are there any safety precautions to consider when building a gas chromatograph with a capillary column?

Yes, there are several safety precautions to consider when building a gas chromatograph with a capillary column. These include wearing proper personal protective equipment, handling compressed gases with caution, and following all safety guidelines provided by the manufacturer. It is also important to properly dispose of any hazardous materials used in the instrument, such as solvents and chemicals.

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