Building a GC with a FID

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dek442's picture
Building a GC with a FID

Hello everyone!
I'm new here and I really need some technical/mechanical help on a project I'm working on here at Texas A&M.
I am currently working a project to build a GC with an FID. After deciding this I realized the difficulty in finding a good publication or paper as a reference on how to do this. What I'm asking is if anyone can run down the steps and basic procedures on how to accomplish this task (or point me in the direction of a paper/publication/book/website on the matter). I have access to an electronics lab to add any sort of electrical parts to our detector. In addition, I will have the funds to order a column, injection port, and any and all other supplies I may or may not need, including chemicals. I have taken both an analytical chemistry class and lab, so I know all the background information on the subject of gas chromatography as well as flame-ionized detectors. As for carrier gas, we have access to all of the standard gasses, and the analyte will be various hydrocarbons, which, from my understanding, are the compounds to be used with an FID. 
Thanks in advance for any and all help!
Note: I'm not looking for an university lab procedure to build a very simplistic GC. For example, I've run across procedures to build a GC using laundry detergent as a mobile phase and some that don't make their own FID; this is not what I'm wanting. I really need someone with a mechanical/technical background to help me actually construct a GC with a working FID (since I will have access to facilities to accommodate any construction and expense); granted, it will be basic, but not so amateur that I could construct one at home.

Dr. Analytical
Dr. Analytical's picture
The first obvious question is

The first obvious question is "why?"  Is there some pedagogical reason to buidl one, or is your advisor too cheap to buy one?  I understand that most universities will not want to spend $30,000, but you can buy one for much less than that. 

Are you hoping to develop some new ideas for GC components, or some other improvements?  That is clearly an area of need for all instruments.

But if you want to build one on your own, I suggest finding an old book on GC (several written in the 70's that would have more detail on the mechanical aspects.  There were a few journals that published details as well. 

As you know, you are going to need pressure/flow regulators and sensors, heating elements and thermostat/control capabilities, and power supplies, in addition to the box that holds everything.

To build your own column you will need a long tube of either glass or stainless steel, unless you want to draw your own fused silica capillary.  And you mentioned columns made with laundry detergent as the stationary phase (not mobile phase) - actually they were quite successful.  They were packed with Tide, and became known as Tide columns. 

Keep us posted on your progress.

dek442's picture
Thank you so much for your

Thank you so much for your reply!
The reason why I'm doing this is for a project that is required. Most students choose to simply analyze compounds using the instruments available, but I thought that this would be a more interesting and educational project. 
Here is what I have so far:

text-indent:-.25in;mso-list:l0 level1 lfo1">1)      PARTS – Four main parts: Carrier gas w/pressure reg., Injection site w/ oven, Column, and the detector.
a)      Carrier gas w/pressure regulator

auto;text-indent:-.25in;mso-list:l0 level3 lfo1">i)        Carrier gas – H­2 because we are using an FID, it will be easier with a flammable gas.

auto;text-indent:-.25in;mso-list:l0 level3 lfo1">ii)       Pressure Regualator – Provided in the lab, they have plenty

auto;text-indent:-.25in;mso-list:l0 level3 lfo1">iii)     Also using a molecular sieve which we can make in the lab with glass ware and CaCl2, will remove moisture and anything else that could interfere with our results
b)      Injection site w/oven

auto;text-indent:-.25in;mso-list:l0 level3 lfo1">i)        Oven  - Three parts: The box, heating element, and temperature sensor.

auto;text-indent:-.25in;mso-list:l0 level4 lfo1">(1)    Metal box – will cover the injection port, column, and the FID. It will be insulated with either glass wool or something from home depot. Also need med temp rubber tubing to use as fittings for the openings

auto;text-indent:-.25in;mso-list:l0 level4 lfo1">(2)    Heating element – Something like this:

auto;text-indent:-.25in;mso-list:l0 level4 lfo1">(3)    Temperature control – Controlled by either a thermometer, or by this:

auto;text-indent:-.25in;mso-list:l0 level3 lfo1">ii)       Injection site – Two option that I see, can come up with more. I like the first

auto;text-indent:-.25in;mso-list:l0 level4 lfo1">(1)

auto;text-indent:-.25in;mso-list:l0 level4 lfo1">(2)
c)       Column – I haven’t looked into these much yet
d)      Detector – FID using this style: Hughes, D. E. P J. Chem. Ed. 1965, 42, 450.

auto;text-indent:-.25in;mso-list:l0 level3 lfo1">i)        Need to have connector for end of GC that turns up

auto;text-indent:-.25in;mso-list:l0 level3 lfo1">ii)       I can provide a Sterican long needle or we can use the shorter ones that the lab has as the cathode

auto;text-indent:-.25in;mso-list:l0 level3 lfo1">iii)     The flame doesn’t need to be strong and the anode needs to be fairly close

text-indent:-.25in;mso-list:l0 level3 lfo1">iv)     The amplifier:

At this point I was wondering if you could expand more on how to build the column. Is there a relatively simplistic way of attaching the injection port? Thanks so much for the help!

dek442's picture
 Here is an update on the

 Here is an update on the column: 
a)      Column – Fused silica capillary column, suggested for hydrocarbons

auto;text-indent:-.25in;mso-list:l0 level3 lfo1">i) column

text-indent:-.25in;mso-list:l0 level3 lfo1">ii) for connecting the column to the injector port and the FID
And a final purchasing list of all the items I will need.
List of Items:
1)      H2 gas cylinder
2)      Pressure regulator
3)      Molecular sieve - , , with glass wool at each end, and CaCl2 beads as the sieve in the open space in between.
4)      Keck clamp(s)
5)      Med temp rubber tubing, small diameter
6)      Three way glass:
7)      Metal box: made by us
8)      Insulation: probably a bunch of glass wool
9)      Heating element:
10)   Temp sensor: Thermometer or this
11)   Really small rubber septum for the three way glass injection side
12)   Heat shrink? Possibly
13)   Column:
14)   Ferrules for column connection:
15)   Sterican long needle or short needle for Cathode
16)   Wiring to connect amplifier and use as Anode
17)   Amplifier:
18)   Vernier connection for computer
19)   Small metal clamps and screwdriver for those
20)   Razor blade for cutting tubing
I will continue to update you as I begin building. I will also be taking pictures.

Dr. Analytical
Dr. Analytical's picture
Well, you certainly have been

Well, you certainly have been busy!

Regarding the column, do you still want to build one or just buy one?  The capillary kind will probably not work because they have very small capacity and you would need to split the sample at the injector.  A packed column would be easier to make (or buy).  You can buy the empty tubes from Restek I think.  Otherwise, you could learn glassblowing skills and bend your own.  :)

You will need a rubber septum for the injection port, and that is usually kept at a different temperature than the oven.  Similarly, the detector is at a different temperature as well.  Both need to be higher than the BP of your compounds to prevent condensation.

I didn't look closely at the list, but do you have a power supply for the FID?  It needs to be about 200 V between the flame and collector.

Maybe as you get further along, you could post/send a schematic, which would be easier to understand.

EricWilson's picture
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