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Does the age of the perfume matter in a gcms?

Logocracy

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I've just commissioned a gcms analysis of two perfumes that were discontinued over 25 years ago.

The perfumes themselves have been very carefully stored and their general DNA still smells the same as brand new (with perhaps some very very subtle vinegary sharpness).

How much would a perfume 'change' during this time? Do naturals become rancid or breakdown? Are there any common chemical reactions to expect over that timeframe? I've heard that some molecules become diethyl acetal forms of what they were, is that good or bad? How much would the age normally affect a GCMS analysis?
 

David Ruskin

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As always it depends. This time it depends on how the perfumes were stored, if the bottles were full and unopened, or opened, and, of course, the formulation. Aldehydes will, over time, react with the ethanol to form acetals. Indeed one can gauge how old a sample is by the amount of acetals present. Aldehydes, depending on storage, can oxidise to acid. Ethanol can, over time, and given the right conditions, oxidise to acetic acid. Schiff's Bases may form if the starting materials are present. All of these are minor changes which won't spoil your GC/MS analysis.
 

mnitabach

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I don't know if Manny Cross is around here at all anymore, but he used a GCMS of a degraded sample of 40 Love by Jean Desprez as a basis for composing his 40 Rogue reconstruction. He would have a vast amount of insight into your question.
 

pkiler

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1926 Guerlain Djedi gcms had about 45% of unidentifiable molecules, because of age that has transmutated naturals and single molecules into new molecules that weren't in the library of the labs that tested it.
 

Logocracy

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1926 Guerlain Djedi gcms had about 45% of unidentifiable molecules, because of age that has transmutated naturals and single molecules into new molecules that weren't in the library of the labs that tested it.
This is interesting. I got one of the GCMS reports back and it only added up to 78% of the formula, the rest was unidentifiable. The perfume is from the late 90's/early 2000's, so I think there would be a good catalogue, but if the naturals haven't kept well it could explain the gaps, perhaps?
 

Logocracy

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As always it depends. This time it depends on how the perfumes were stored, if the bottles were full and unopened, or opened, and, of course, the formulation. Aldehydes will, over time, react with the ethanol to form acetals. Indeed one can gauge how old a sample is by the amount of acetals present. Aldehydes, depending on storage, can oxidise to acid. Ethanol can, over time, and given the right conditions, oxidise to acetic acid. Schiff's Bases may form if the starting materials are present. All of these are minor changes which won't spoil your GC/MS analysis.
This is a great answer (and reassuring that I haven't wasted money!).

I'm guessing if I see something like "Helional" and "Helional Diethyl Acetal", it's probably the same molecule, just partly degraded into an acid?

And I'm guessing if the GCMS comes back with a high amount of Acetic acid and other acetals, then the perfume is partially spoilt, but still reliable?
 

David Ruskin

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Probably true, although it is acetal not acid. As has been mentioned by others some essential oil can degrade over time if subject to oxidation. Limonene rich oils (i.e. citrus oils) may change; amount of limonene will decrease whilst para cymene will increase. As with every GC/MS analysis, it is vital to smell the original sample against your trials, and if possible have your first trial analysed by GC/MS to compare. I realise this is not always possible (probably impossible) but ideally a good thing to do.

Acetic acid is an acid; an acetal is the reaction product between an aldehyde and an alcohol.
 

Logocracy

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I got the second GCMS back, not sure if you can help me work out these molecules?

Methyl piperonyl ketone - having googled this, I haven't found much on it other than it is a precursor to amphetamine. In 'Scents and Chemistry" p.197 suggests part of a Diels-Alder reaction of homomycrene and Methyl isopropenyl ketone (not sure if this is the same molecule) creates dienophile. Not being a chemist, I have no idea what this means, but does it mean methyl piperonyl ketone just a by-product of a reaction in the perfume overtime (so perhaps ignore in a formula)?

1,12.3,3-Pentamethyindane - which in my research seems to just be the chemical name for Cashmeran? However Cashmeran is listed as another line item in the report. What are the reasons why it would it be separated?
 

pkiler

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I got the second GCMS back, not sure if you can help me work out these molecules?

Methyl piperonyl ketone - having googled this, I haven't found much on it other than it is a precursor to amphetamine. In 'Scents and Chemistry" p.197 suggests part of a Diels-Alder reaction of homomycrene and Methyl isopropenyl ketone (not sure if this is the same molecule) creates dienophile. Not being a chemist, I have no idea what this means, but does it mean methyl piperonyl ketone just a by-product of a reaction in the perfume overtime (so perhaps ignore in a formula)?

1,12.3,3-Pentamethyindane - which in my research seems to just be the chemical name for Cashmeran? However Cashmeran is listed as another line item in the report. What are the reasons why it would it be separated?
I'd bet that this Methyl piperonyl ketone is a reactive / degradation product from Heliotropin, which is an aldehyde AKA Piperonal.

Yes, 1,12.3,3-Pentamethylindane *might be cashmeran, or could be something slightly different.
 

pkiler

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Yes, you will regularly see Aldehyde Diethyl Acetals in GCMS results, where the aldehyde and the ethyl alcohol create a new acetal.
 

Logocracy

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I'd bet that this Methyl piperonyl ketone is a reactive / degradation product from Heliotropin, which is an aldehyde AKA Piperonal.
Now that makes sense. There is Heliotropin in the formula. Thank you!
 

mnitabach

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Now that makes sense. There is Heliotropin in the formula. Thank you!
Perhaps this is obvious, but just to close the loop: you would increase your predicted formula dose of a precursor (such as heliotropin) by the molar equivalent of the dose of the degradation/adduction product (such as methyl piperonyl ketone).
 

Alex F.

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1,12.3,3-Pentamethyindane - which in my research seems to just be the chemical name for Cashmeran? However Cashmeran is listed as another line item in the report. What are the reasons why it would it be separated?
A quick search through my books turned up this:
According to Surburg and Pranten, Common Fragrance and Flavor Materials, 6th ed., 2016, p. 171, 1,1,2,3,3-pentamethylindane is the starting material in the synthesis of galaxolide, see also Scent & Chemistry, 2nd ed., 2022, p. 337. My guess would be that Galaxolide preparations may contain traces of unreacted 1,1,2,3,3-pentamethylindane, and/or it may also be formed again when galaxolide breaks down.
Based on this, I'd attribute it to Galaxolide rather than Cashmeran, 1,1,2,3,3-Pentamethyl-1,2,3,5,6,7-hexahydro-4H-inden-4-one.
 

Logocracy

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Perhaps this is obvious, but just to close the loop: you would increase your predicted formula dose of a precursor (such as heliotropin) by the molar equivalent of the dose of the degradation/adduction product (such as methyl piperonyl ketone).
I'm thinking the same. I'm doing two separate trials, one with just what shows up in the report (sans acteals); the other by combining the molecule and their related acetal amounts (as well as the Heliotropin with the MPK).
 

Logocracy

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A quick search through my books turned up this:
According to Surburg and Pranten, Common Fragrance and Flavor Materials, 6th ed., 2016, p. 171, 1,1,2,3,3-pentamethylindane is the starting material in the synthesis of galaxolide, see also Scent & Chemistry, 2nd ed., 2022, p. 337. My guess would be that Galaxolide preparations may contain traces of unreacted 1,1,2,3,3-pentamethylindane, and/or it may also be formed again when galaxolide breaks down.
Based on this, I'd attribute it to Galaxolide rather than Cashmeran, 1,1,2,3,3-Pentamethyl-1,2,3,5,6,7-hexahydro-4H-inden-4-one.
Interesting. I didn't know this. Thanks for sharing. The perfume is 12% Galaxolide, which is the third largest percentage in the formula, which makes what you say likely; and the 1,1,2,3,3-Pentamethylindane is just a trace amount (0.019%). But their evaporation positions are very different, which is also very interesting. I'm learning a lot here.
 

mnitabach

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Interesting. I didn't know this. Thanks for sharing. The perfume is 12% Galaxolide, which is the third largest percentage in the formula, which makes what you say likely; and the 1,1,2,3,3-Pentamethylindane is just a trace amount (0.019%). But their evaporation positions are very different, which is also very interesting. I'm learning a lot here.
You are teaching a lot, too! Definitely appreciate your detailed explanations of this journey. Please keep it up!
 

Alex F.

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Methyl piperonyl ketone - having googled this, I haven't found much on it other than it is a precursor to amphetamine. In 'Scents and Chemistry" p.197 suggests part of a Diels-Alder reaction of homomycrene and Methyl isopropenyl ketone (not sure if this is the same molecule) creates dienophile. Not being a chemist, I have no idea what this means, but does it mean methyl piperonyl ketone just a by-product of a reaction in the perfume overtime (so perhaps ignore in a formula)?

I looked for this, too, and got a hit in Arctander's book on ACs. I couldn't find a preview on Google Books, so I'm quoting the entry:
I did find a preview after all. I prefer that to quoting lengthy passages: Arctander, Steffen: Perfume and Flavor Chemicals (Aroma Chemicals), vol. II, 1969, "2010: 3,4-Methylene dioxyacetophenone" (bottom of the page plus following page, "methyl piperonyl ketone" under synonyms). (C₉H₈O₃, CAS-# 3162-29-6?)

So I'd file that as "probably part of an unknown perfume base". (PS: Maybe Messrs. Frater and Leira can help you identify the base. Or maybe this is a wild goose chase and someone knows whether this 3,4-methylenedioxy-acetophenone commonly appears in aged perfumes containing piperonal/heliotropin, like Mr. Kiler suggested.)

EDIT: I browsed through my collection of GC/MS-analyses (mostly courtesy of Laudamiel/fragrance.drama), and I found another "methyl piperonly ketone" (AKA "piperonyl methyl ketone", C₁₀H₁₀O₃, CAS-# 4676-39-5) in some of them - sometimes without heliotropin (e.g. Acqua di Giò, One Million, Polo Blue edp), once in a higher quantity than heliotropin (Polo Blue edt), and present or not present depending on the type (in YSL's Libre). I'm confused now. Does your report include a CAS-# for that "methyl piperonyl ketone"?
 
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Keltsu

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As a chemist I would expect that Methyl piperonyl ketone (CAS-# 4676-39-5) is product from safrole oxidation, especially if the sample is old. Quick look would say that this happens with molecular oxygen, usually with a catalyst of course in scientific literature. Some naturals that would have this include camphor tree (Ocotea pretiosa), anise, nutmeg, cinnamon, and black pepper oils.

What comes to 3',4'-(Methylenedioxy)acetophenone (CAS-# 3162-29-6), it contains one less carbon than Methyl piperonyl ketone.
 

jsweet

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Logocracy

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Methyl piperonyl ketone a.k.a PMK appears to be the most direct precursor to illicit MDMA manufacture. In that context it is usually derived from safrole/isosafrole rather than piperonal, according to some studies.

"The global licit trade in PMK is almost non-existent" according to:


View attachment 337957

In this case I'm guessing it's an oxidation product, but not necessarily from piperonal.
Interesting to see Helional here in the graph as well.
The fragrance contains Helional and the GCMS showed more Helional Diethyl Acetal than actual Helional. I wonder if Helional also contributed to the appearance of PMK (along with the Heliotropin)? If so, it's seems that Helional breaks down/changes a lot quicker than most other molecules over time.
 

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