Please help!!! Question for GC calibration

[LUXIAOXIAO]

Hello everyone,

I want to analyse the concentration for my reaction products from FID detector, those products are ethanal, acrolein, propylene oxide, acetone and propanal. It's gas phase reaction and all the products are in gas phase and directly injecting to GC through six-way valve.

I have no money to buy standard gas to calibrate so I bought the high purity liquid solution for each of all those components.

Questions,

1. How I use those solution to calibrate my GC? I want to dilute those solution and make a standard solution for each of them. How to calculate the concentration for the final solution I will make? I should calculate the mass or the volume of each of the components?

2. Is there any other way to calibrate my GC FID detector with those high purity liquid solution for each of all those components?

Thanks!

[rb6banjo]

Tricky business making gas standards from neat liquids in the lab. I've never had a great deal of success - mostly, what I've tried has not been very reproducible.

What if you injected 1 µL of each into a sealed, 100 mL serum vial and heated it to 60 °C (b.p. of acetone is 56 °C). You would be sure that everything in the vial was vapor, then you need to aspirate a known amount of this gas into a warm syringe and then inject it into the GC. Or, if that's too concentrated, you could inject that into another vessel and dilute it with some other gas to reach the desired concentration.

Serum vials:

http://www.fishersci.com/shop/products/ ... 15/p-45371

Other vessel that I use for this sort of dilution is:

http://www.restek.com/catalog/view/45330

I evacuate the canister and then affix a septum to the opening. I open the valve so that the vacuum pulls against the septum and inject into the canister through the septum. Close the valve and then dilute the contents of the canister with some other inert gas (helium, CO2, etc.).

I've used this sort of technique to make the standards but I've always had another, certified standard, to calibrate my mixture against. That way, even if I don't hit my target, at least I know what I hit.

Good luck. As I said, tricky business making gas-phase standards without all of the correct equipment.

[LUXIAOXIAO]

Thanks!
But the acrolein is extremely corrosive and air sensitive, I can not prepare it like that way, what do you think?

Thanks again!

[rb6banjo]

I am unaware of any special problems with acrolein in air. Here in the US, our Environmental Protection Agency (EPA) measures it in the atmosphere.

http://www3.epa.gov/ttnamti1/files/2009 ... rolein.pdf

I would think if it were that reactive in air, you wouldn't have to worry about it as an environmental contaminant.

You could certainly fill the serum vial with an inert gas like helium. Argon might be better because it is heavier than air. It would make it easier to purge out the air that was originally trapped in the vial.

[AICMM]

LUXIAOXIAO,

Summa can is a good option (pricey.) You could evacuate and then back fill with argon.

Static dilution bulb might work well for you. Same idea as the serum bottle but more set up for this type of work. Also known as gas sampling bulbs. Find them from Supelco for example. Advantage of either of these containers is that you can dilute your sample in solvent for lower levels. One microliter of a neat does not make a very dilute sample, at least not with SDB. In the case of the SDB, you can afford to toss the mix everyday and re-make it after purging the bulb with fresh air or argon.

In the gas of dilution bulb, it is wise to add several glass balls to the bulb in order to aid mixing.

You can permeate these but it will take you a long while to figure out the concentrations so probably not the best route.

Best regards,

AICMM

[osp001]

It is possible to make gas standards with a vial of suitable solvent, a Pasteur pipette, a gas supply, and a good (0.1 mg) analytical balance. Use the Pasteur pipette and a bit of tubing to bubble gas up through a vial of solvent, using the difference in mass to determine how much gas has dissolved in the solvent.

Tricky, and (as has already been noted) reproducibility suffers.

[Peter Apps]

It is possible to make gas standards with a vial of suitable solvent, a Pasteur pipette, a gas supply, and a good (0.1 mg) analytical balance. Use the Pasteur pipette and a bit of tubing to bubble gas up through a vial of solvent, using the difference in mass to determine how much gas has dissolved in the solvent.

Tricky, and (as has already been noted) reproducibility suffers.

With most (volatile) organic solvents the difference in mass will be due to solvent evaporation, and even if some of the gas dissolves in the solvent you now have a solution of gas in solvent, not a vapour of solvent in gas, which is what the OP needs.

Peter