Chromatography Forum

I have had a request to identify a smell. My plan would be to pass a volume of gas through an absorbant, extract it with a suitable solvent and identify the compounds using gc/ms. I plan to use activated carbon as the absorbant. Unfortunatley we do not have an ATD hooked up to our ms or life would be so much easier!
Does anyone have any other ideas for doing this? Are there kits available?

GCguy

You might try SPME. You can pul a fair quantity of material out of air with a SPME fiber. There are kits of fibers so you can try several polairities fairly easily.

Hi

Air sampling is a science of its own so to speak, but for identification purposes, your initial plan with active carbon may work.

As Don stated, SPME is an option, may not be so complicated (expose fibre for x minutes in bulb/vial, then inject and desorb for x min at temp Y)

Sigma-Aldrich is one supplier with kits, air sampling pumps, adsorbents etc, they also have some applications with SPME and sulphur gases with GC/MS identification.

If you have a SHE/EHS department, they might be able to help you.

I would not be surprised if you find a good chunk of peaks in your sample, so I would suggest sampling a non smelly area as reference.

We need more detail on this - is the smell in ambient air ?, in a particular product etc ?. What is the nature of the smell ? Do you have control samples with no smell ?

If you sample ambient air or a food or beverage for e.g. you will get a forest of peaks, numerous of which will turn up library fits for chemicals that have nasty odours at high enough concentrations. The trick will be to match a particular chemical to the particualr problem smell. GC-sniffing is hugely powerful for this as long as you have a distinctly recognisable smell.

Peter

The smell is in the air in a storage warehouse. I know all the things that should be in the warehouse and what all the decomposition products are. The actual testing method should be straight forward. The issue is the sampling. Excellent idea about taking a "blank" form a non-smelly area. I have done some searching and have found information about Radiello, their gear looks quite good. does anybody have any experience of them?

Hi GCguy

Unless you are going to be doing a lot of this I would not invest a lot of money in hardware. A charcoal trap ( or a charcoal monitoring badge) with solvent desorption, or SPME (which you can do just with the fibre, you don't even need the holder thing) is as good a starting point as any. There are a host of gadgets and tricks that have been developed for this job - whether any of them work will depend on what the smell is, and especially what its sensory detection threshold is, for e.g. if you have a disinfectant odour due to chlorophenols be prepared for their peaks to be obscured by all the other airborn organics, if its a strong smell of bananas maybe you'll strike lucky with a huge isoamyl acetate peak.

Peter

Thanks for the help. I think I have solved the issue. Visited the warehouse and it stinks of the product. The bags it was packed in had not been sealed correctly. Unfortunatly no one made the connection, it smells like the product mmmm what could it be???

I have just done some extractions on the cardboard outer packs, control i.e. non smelly and a smelly pack...

GCguy

gcguy,

For future reference, you might look at NIOSH methods for sampling methods for ambient air. Quite a few are tubes or badges with solvent desorption, typically CS2. Also might look at 3M badges since, I believe, these are passive and don't require sampling pumps.

Best regards.

a quick and easy way to sample an odor in ambient air is to use a 100mL air tight syringe with a luer lock tip. Pull in a sample of clean fresh air, and hook the syringe to the manual inlet of your purge and trap system. During the purge cycle, push the air into the system with slow steady pressure. Any organics in the air will be grabbed up by the trap and can be analyzed like any other volatiles. Then repeat with the smelly air...You will be pumping a big slug of oxygen thru your system, but I have done this on several occasions on several different systems, and none of them suffered any noticeable ill effects - it works.

Hi gcguy

"Visited the warehouse and it stinks of the product."

Brilliant.

The most sophisticated and selective odour sampling and analysis sytem, backed up by unmatched data processing - let's hear it for the human nose

Trouble is nobody ever wants to pay for you to walk into a place and say "Hm smells like so and so, and look there's some unsealed bags of the same stuff".

Peter

For odor analysis, the sampling part is not hard, there are a few developed methods, mostly by canisters or by tubes. The hard part is to identify the compounds that cause the smell. We never had the luck to pinpoint the smelling copound(s). If anyone can develop a method for odor analysis, they should be a millionaire if not billionaire by now.

"If anyone can develop a method for odor analysis, they should be a millionaire if not billionaire by now."

Really, tell me more !, I've done lots of this, and identified lots of smells, and the only kind of billionaire I am is if you count in Zimbabwe dollars.

Peter

"If anyone can develop a method for odor analysis, they should be a millionaire if not billionaire by now."

Really, tell me more !, I've done lots of this, and identified lots of smells, and the only kind of billionaire I am is if you count in Zimbabwe dollars.

Peter

yeah, pretty much everybody is a billionaire in Zimbabwe...

I was talking about a system (or a method) that can make a positive identification of the odor compound(s) in a matter of a few seconds ONSITE. Most of odor in office building or at home doesn't last long. By the time you set up the canister, tube or SPME, the odor is long gone. If somebody can make a system like that, he should be superrich, unless he invested all his money with Madoff.

I just love the sound of goalposts as they move around