Fragrace GC Analysis

[meystingray]

So forgive this question, as I'm new to GC analysis. My company is looking to quantify the level of a fragrance in some of our plastic products using a GC. Does anyone have any experience doing this?

Should I assume that all fragrance will come out of the product, and if so, can I get away with doing a bulk extraction and injection into the GC?

Or should I only consider fragrance coming out of the product, and do a headspace analysis?

Thanks for the help.

[Steve Reimer]

Do you want to quantify the amount of fragrance in the plastic? If so you will need to either extract it and possibly do some clean-up of the extract or be able to relate how much fragrance is in the plastic to the amount in the headspace under the conditions used.
If you just want to know how much is released then headspace would be easier.

Extracts from plastic can be relatively clean or a horrible mess depending on the plastic and the solvent.

[meystingray]

Good question Steve. The goal really is to develop a method to quantify fragrance retention times to enable us compare fragrance performance. Longer lasting fragrances are better, obviously. It's sounding like doing repetitive headspace analysis over time and watching a few of the peaks might be the way to go.

This brings up a related question - how does one really "quantify" fragrance strength in GC (also, without M/S) as it relates to my nose? Should I pick a few of the strongest peaks and watch them over time, or do I need to look at the sum total of all the peaks?

[Peter Apps]

Headspace is the way to go - it will give you a good relative measure of decline on fragrance emission with time.

Because different compounds have very different odour intensities the size of the peak for different compounds does not necessarily correlate with odour intensity. You can probably find detection thresholds for some of your compounds, the lower the threshold the more intense the odour, all else being equal.

There has been a huge amount of work on release of insect pheromones from polymer dispensers - try a search for pheromone slow release, pheromone controlled release, and pheromone dispenser. That will give you some ideas of methods to follow and how to design the experiments.

Peter

[GOM]

Hi

First, it is always useful to think of a plastic/polymer as being a very thick liquid, therefore, due to the different volatilities and polarities of the components of the fragrance. the permeation into the headspace will not fully reflect the original abundances in the plastic. i.e. You will not see all of the fragrance components in their original abundances unless the sample is is totally dissolved in a suitable solvent

Next, the response of the FID can bear little relationship to your nasal response (for example. for protection, our noses have evolved to be more sensitive to certain functional groups, which indicates that there is a microbial presence that could harm us - and our response to alkanes is quite low)

So headspace analysis over time compared to the original fragrance profile is the way to go

Regards

Ralph

[rb6banjo]

I have some experience in this game. I use headspace SPME pretty much exclusively. I haven't found an instance where it hasn't worked for me. Is it too "super secret" for you to mention what fragrance compounds and what plastics are your concern?

Some earlier stuff I displayed in one or more of the forums as part of a discussion on doing fragrances in hand soap:

viewtopic.php?f=2&t=24526&p=117174&hili ... is#p117174
viewtopic.php?f=5&t=24987&p=119370&hilit=soap#p119370

Going at it by headspace SPME directly in the plastic will probably be your best bet but you really need to understand how your fragrance compounds behave in the plastic to get good quantitative results.