Chromatography Forum

Hey everyone,

We have a Gerstel MPS automatic sampler attached to our 6890N GC. We have been having a lot of problems using this system in SPME mode. It is very hard to get info on gerstel products off the internet!!

The system is bending, and breaking SPME fibres all the time. We have checked all the alignment and changed to thinner septas however the problem is still occuring.

Two ways in which fibres are breaking are:

1. the agitator is bending the needles during absorption (agitator speed is not very high and alignment is correct)

2. The needle is being injected into the side of the inlet and creating a Z shape in the fibre. (alignment is ok, but the system randomly chooses to inject out of position on occasion)

Any information about the system that could be causing these problems would be greatly appreciated.

Thanks,
Jade

Jade,
A few things we've found to be helpful with our Gerstel (and perhaps you've tried them all already) are:
- cycle the power to the rails every few days (or at the beginning of each day before the run). We close down ChemStation, then turn off the rails, then hum a tune. Then turn the rails on, then open up ChemStation once they have gotten themselves ready for the day.
- change the bungee cords in the heads. We've found that if we don't change these approximately once a year, we start having problems with z-ed needles
- We haven't had any problems with the SPME needles being bent--do you use the 23 gauge? These were recommended to us, and they seem to work very nicely

Good luck.
Michele

Thanks michelle,

It turns out we had to reinstall the hardware on the computer and reinstall everything from scratch and upgrade the software. Since then we haven't had any trouble fingers crossed.

Thanks for your help though