Chromatography Forum

Morning all,

Whilst browsing some technical notes to try and improve my sampling methods using SPME I happened across a relatively new technology by Markes, which is supposed to be an improvement on traditional SPME fibres: https://www.markes.com/Products/Samplin ... ction.aspx

I was wondering whether anyone on here has had any practical experience with this technique and whether it works any better than traditional SPME?

I hasten to add that I am not affiliated with Markes in any way and this isn't designed to be an advertisement. I am a PhD student at a University in the UK.

Best wishes,

Joe

Hi Joe

I know that you are interested in headspace analysis of volatiles

Broadly speaking this falls into 2 categories

1. Static - for example SPME of the headspace with subsequent thermal desorption in the GC injection port
2. Dynamic - for example a flow over the headspace through an adsorbent, which is then thermally desorbed - this potentially gives more analyte to be detected

This one appears to fall into the 1st category.

I have no experience of it so can only make the following comments based on looking at the brochure link that you supplied

1. They say that it is PDMS based so that may alter the selectivity of analytes adsorbed
2. Yes, with a higher ad/absorbent level it will adsorb more than the thin film on an SPME fibre
3. It appears to require a lot more ancillary equipment to be purchased - it appears to be part of a larger TD system that they are selling

At the end of the day, get Markes to demonstrate the usefulness on one of your samples before committing to a large financial outlay They have been very helpful with me in the past and are very experienced in headspace analysis

Regards

Ralph

Good morning Joe

This was invented in Stellenbosch by Ben Burger;

Ben V. Burger ∗, Brenda Marx, Maritha le Roux, Wina J.G. Burger. 2006. Simplified analysis of organic compounds in headspace and aqueous samples by high-capacity sample enrichment probe. Journal of Chromatography A, 1121 (2006) 259–267.

I'll e-mail you a pdf.

Peter

We bought a TD unit earlier this year. I've been a devout SPME user for years up until this point. I am discovering that the "extra capacity" can be a bit of a curse. It seems that you have to live with higher backgrounds. I've been dabbling with extra pdms sampling devices (no names) and I believe I'm on the right track BUT I've come to the realization that there will always be higher backgrounds as a result of using these devices. SPME has such a small mass, it's easy to clean the fibers to nearly zero extraneous emissions. You might have limited capacity with the SPME fibers. They do have amazing capacity for such small-mass devices!

Same with Tenax traps. I don't know that you can ever get them to zero residuals. It's like any technique, you just have to know what it will do for you and what it won't.

Thanks for the replies, they have been most helpful. I contacted Markes this morning and have arranged for them to come and demo the equipment to me using the system we already have.

I will let you know how I get on.

Cheers,

Joe

We bought a TD unit earlier this year. I've been a devout SPME user for years up until this point. I am discovering that the "extra capacity" can be a bit of a curse. It seems that you have to live with higher backgrounds. I've been dabbling with extra pdms sampling devices (no names) and I believe I'm on the right track BUT I've come to the realization that there will always be higher backgrounds as a result of using these devices. SPME has such a small mass, it's easy to clean the fibers to nearly zero extraneous emissions. You might have limited capacity with the SPME fibers. They do have amazing capacity for such small-mass devices!

Same with Tenax traps. I don't know that you can ever get them to zero residuals. It's like any technique, you just have to know what it will do for you and what it won't.

Looks like a PDMS device that's larger than SPME. Something along the lines of the Gerstel Twister but with different sample handling? Always interesting to see new products.
As far as high backgrounds, if you get the chance, setup thermal desorption on a MS/MS system or high resolution TOF. Both cases are real eye openers. MS/MS takes that high baseline and drops it to zero except for your target compounds and allows you to crank up the multiplier. HRTOF lets you look at everything and then pull out your target compounds using mass resolution to eliminate background. Both have their uses.