I'like to increase our sensibility on identification of impurities in active pharmaceutical ingredients by GC/MS...till, now, we use a 6890 and a 7694 by agilent but I heard about dynamic headspace which'd be great for what I want. I know nothing about that. Would someone be nice telling me what it is and if tere are differences between Dynamic HS and purge and trap and spme?? And who sells that kind of products? Are they reliable and all those kinds of things?? Thanks
By GC user on Friday, August 6, 2004 - 04:27 am:
Tekmar used to sell a dynamic headspace sampler, but I'm not sure if they still do. Purge and trap is a type of dynamic headspace, but when people say dynamic headspace they are generally referring to sweeping the headspace with gas, not purging the sample with gas. You can set up any purge and trap for this type of dynamic headspace by using a needle sparger and shortening the needle so the gas enters the headspace instead of the solution.
By chromatographer1 on Friday, August 6, 2004 - 09:17 am:
Dynamic headspace injects a sample of the headspace above the product stored in a vessel onto a GC column. One needs an IN and an OUT connection.
Purge and trap takes a sample of the product and flushes it (purge) with gas while trapping the light components that may 'degas' from the sample. The trap is then reversed and trapped analytes are injected into the injector inlet onto the GC column.
SPME is a fiber coated with a 'trapping material' that is placed above a product in a closed vessel. The fiber is then placed into a heated injector port and the analytes leave the 'trapping material' and enter the GC column.
Static headspace often uses an autosampler that injects an measured amount of the headspace above a product in a vessel. The heating and dissolution of the product can be controlled. This is the most accurate and reproducible method of trace analysis of volatile impurities.
Tekmar, Varian, Agilent, OI Analytical are names you should familiarize yourself. The web will have many hits if you do a search (or even if you open an issue of LCGC magazine ! )
By Ingochrist on Monday, August 9, 2004 - 07:23 am:
If you want to do all those above mentioned techniques with a single unit, please consider the CTC PAL autosampler from CHROMSYS (www.chromsys). It's a robotic unit that switches quickly from one technique to the next and is the only one (beside Varian), which can do SPME.
By chromatographer1 on Monday, August 9, 2004 - 10:21 am:
thanks for the contribution Ingochrist. I tried to include everybody !
By xxx on Tuesday, August 10, 2004 - 07:51 am:
The CTC PAL autosampler is from CTC Analytics Switzerland and not from Chromsys!!!!!
You can purchase one from Gerstel,CTC Analytics,Brechbbueler,Varian or Chromsys and more...
By GC user on Tuesday, August 10, 2004 - 12:13 pm:
The CombiPal is a static headspace instrument, not a dynamic headspace. It is a good instrument, but a real dynamic headspce system will have better detection limits due to larger sampling size.
By Fred on Wednesday, August 11, 2004 - 12:24 am:
Thank you all.As I told you, I have a static headspace (7694 by agilent) and would like some kind of dynamic HS...CTC PAL seems to be something pretty nice..but "Mr GC user" says I could get lower detection limits by real dynamic..so Tekmar, what else??