Thermal Desorption Systems

[akthmps]

We currently have a Markes Unity thermal desorption system connected to an Agilent 6890 GC. To be honest, our opinion is that the TD system is a piece of crap. Constant leaks, transfer line not heating, cold traps breaking, etc. We have sent the machine back to Markes twice, they have fixed problems, a service technician has been here, and to this day we still have problems.

In looking at other possibilities, I have come across the Perkin Elmer and Gerstel thermal desorption systems. Does anyone have a personal favorite?

In my experience using both Agilent and Varian GC-MS systems, I prefer the Varian system (3800 GC with 2200 MS) hands down. So we may end up connecting the thermal desorption system to a Varian 3800 GC rather than an Agilent 6890. If anyone has any comments about this type of configuration, please let me know.

Thanks in advance.

-Aaron

[Earl]

I use a Tekmar 6000 TDU, I have had some problems with leaks in the past, but all in all the system works well. I have it set up with an HP5890/5972. No problems with transfer line heating, just problems with leaks at the TDU tube, and a need to replace the ferrules often.

[GOM]

Hi Aaron,

It's not a great deal of help I know but I was looking at various TD units for a particular application recently, including Markes, PE and Gerstel. In the end I couldn't justify the cost or commit to having a dedicated instrument. Before deciding to stop I was leaning towards Gerstel, pricey but good engineering.

If possible I would arrange to visit a vendor's application lab. For example, if you are in the UK Anatune is the agent for Gerstel and are very happy to accomodate a visit .

Regards,

Ralph

[MikeD]

Aaron

It's horses for courses. In TD applications demanding full automation, the best possible repeatability performance, full control of all gas flows and re-collection of the sample then Perkin Elmer and Markes have no competitors other than each other. They can do everything else that the others can do on the side. We have both systems in our lab.

Gerstel, Tekmar etc serve a different market, different footprint, price points etc. The Gerstel is very well engineered and I like the modular features. In our lab we regard Gerstel, Tekmar etc. as semi-quantitative, but it just depends whether you need the 0.5% repeatability that the Perkin Elmer and Markes systems are capable of or is 5% repeatability OK ? Some of this difference is due to the fact that the "Others" don't have sophisticated and sensitive leak detection systems.

I have emphasised quantitation because that's my special interest, but there are hundreds of applications and it's impossible to say in general that brand X thermal desorber is better than brand Y.

[GOM]

Hi Aaron,

Mike D's comments are very true and PE have been in the TD business a long time (in fact some of Markes people are ex PE).

It is horses for courses but out of interest I have just had a visit this morning from a Gerstel agent and he was showing me the new dynamic headspace thermal desorption system due to be launched in the autumn. To be fair he didn't tell me that it will probably do everything that I ever wanted or will ever need!

Regards,

Ralph