odour testing

[gcguy]

I have three teenage sons. The odour does not dissipate that quickly and it is often obvious as to the nature and the source of the odour.

[Peter Apps]

[JI2002]

Heard of New York's maple syrup mystery smell? It took people in New York from Oct 05 to Feb 09 to figure out where it came from. It's obvious that they didn't find the right people doing the job.

Reading a book about odor analysis in drinks, the authors talked about a case in which they solved the problem by separating the peak from all interference and still couldn't match the spectrum with any known compound after failed effort by another lab for a few month.

I work in air analysis long enough to know that how tricky it is and how experts can make mistakes from time to time. Some people don't know enough to know that sometimes they don't know.

[Peter Apps]

If all identifications had to be based on matching a mass spectrum to a known compound how would we ever identify any new natural products ?, to identify an unknown (i.e. new) compound, in addition to library matching MS you need high res MS, element specifc detection and NMR. The stumbling block is getting enough sample for the NMR, and then fractionating out the compound of interest. This is bound to take a bit of time !

Sampling is the critical step - if you can't catch and release the smelly compound the rest of what you is doomed to fail.

Peter

[Peter Apps]

I have three teenage sons. The odour does not dissipate that quickly and it is often obvious as to the nature and the source of the odour.

http://gut.bmj.com/cgi/reprint/43/1/100 ... e0ffea299e

Gut 1998;43:100-104; doi:10.1136/gut.43.1.100

Identification of gases responsible for the odour of human flatus and evaluation of a device purported to reduce this odour

F L Suarez, J Springfield, M D Levitt

Isn't science wonderful

[rbardsley]

I enjoyed the replys to this and remember work performed by a Kansas State researcher where they collected the odor around cattle, injected it onto GC with the detector of a box of flies. When the flies became excited, he marked the time. He then had a nose piece fabricated and would smell the odors as they came off the GC. He was able to identify grains that attracted flies.

ON the serious side, another technique is FTIR or IR with a 20 M path cell. This is how a lot of atomospheric analysis was/is performed. The IR is none distructive and the sample could be "collected" and passed onto the GC/MS. The spectra also provides numerous clues to the chemical composition and structure of the odor. A large plastic bag could be used.

MRI in KansasCity developed a collector called a SpinCon, which is now commercially available. Depending on where the odor is coming from this appartus might be able to collect and concentrate in water the odor for analysis.

I understand your fustration on this as once a long time ago, I was requested to analyze air sample for odors that were burning the eyes and throats of the residents. End result was that a cresote coating had breached the vapor barrier and was causing the issues. All of the cannisters, etc did not detect them prior to analyzing the wood.

Good Luck

[perfumer]

"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

What about Luca Turin?

[Peter Apps]

What about him ?

Peter