determination of propellants in spray canisters

[andros]

Can anyone help on how to determine propellants like methane & propane in spray cans?

[Don_Hilton]

How about discharging the can into a series of gas sampling bags and sampling the gas in the bags? (I would expect some of the propane to be condensed in the full can, if there is a significant quantity of propane present.) - then simply sample the gas phase whith a syringe and into the GC... (This assumes significant levels of methane and propane that would show up with a syringe injection, if methane and propane are the main components of the propellant)

[Consumer Products Guy]

Can anyone help on how to determine propellants like methane & propane in spray cans?

Put a non-lubricated condom (preferably unused) over the top of the can, push down on the spray button, then insert a gas-tight syringe (preferably one with a shut off valve) into the sample, extract sample, inject into your GC or GCMS.

I like this better than piercing the can with a piercer assembly. Our assembly came from Alltech but I believe it's now discontinued.

[AICMM]

Andros,

Are you looking for impurities, identification or concentration? If the last one, this would be a very interesting problem.

Valco makes an aerosol can adapter. You could hook this up to a liquid sampling valve and block in the sample but you would have to handle the pressure. You could use the adapter to a gas sampling valve much easier since you could afford to let the gas expand at that point but you will probably get some air incursion.

A Q (PLOT, micro-packed or packed) should work pretty well for this separation, especially if using an FID.

Best regards,

AICMM

[andros]

How about discharging the can into a series of gas sampling bags and sampling the gas in the bags? (I would expect some of the propane to be condensed in the full can, if there is a significant quantity of propane present.) - then simply sample the gas phase whith a syringe and into the GC... (This assumes significant levels of methane and propane that would show up with a syringe injection, if methane and propane are the main components of the propellant)

Thank you for your idea. GC with FID I presume. Do you know the analytical method ie. Temp, type of column and flows that we can use on the GC for this analysis?

[Don_Hilton]

GC FID would work. For selection of column and conditions, the other components present in the mix are important, as they can transfer to the GC column. And, you need to be able to get everything off.

For separation of methane and propane, my first thought would be to go to a mol sieve type of column -- note the advice from AICMM, above. These compunds are not particularly well retained on the commonly used capillary columns, like wax or DB-5 types. For condions, take a quick look in the column catalog - there will be application notes.

[andros]

Andros,

Are you looking for impurities, identification or concentration? If the last one, this would be a very interesting problem.

Valco makes an aerosol can adapter. You could hook this up to a liquid sampling valve and block in the sample but you would have to handle the pressure. You could use the adapter to a gas sampling valve much easier since you could afford to let the gas expand at that point but you will probably get some air incursion.

A Q (PLOT, micro-packed or packed) should work pretty well for this separation, especially if using an FID.

Best regards,

AICMM

Thanks for your reply

[andros]

GC FID would work. For selection of column and conditions, the other components present in the mix are important, as they can transfer to the GC column. And, you need to be able to get everything off.

For separation of methane and propane, my first thought would be to go to a mol sieve type of column -- note the advice from AICMM, above. These compunds are not particularly well retained on the commonly used capillary columns, like wax or DB-5 types. For condions, take a quick look in the column catalog - there will be application notes.

Thanks for your reply

[Chef Tom]

Just a thought here.
It's a can of paint.
Paint is in the bottom. The tube inside the can goes to the bottom and the gas pressing down on the paint pushes it out the tube.

hmm, flip the can over and press the nozzle, you should get a bit of paint then the tube will empty and you get straight propellant no mess

Ciao

[chromatographer1]

Don,

Mole Sieve for propane? That would take some temperature and time for propane.

Perhaps you meant porous polymer.

A thick film methyl silicone capillary would separate methane and propane at ambient temperatures.

But a porous polymer, even a short packed column or a 5 meter capillary column should separate C1 and C3 easily. Many other packed columns would work well, but not too many capillary columns.

best wishes,

Rod