Dear list members:

I need your help for two unrelated questions:

1. Is it true that chemical reactions involving C-X bond breaking or
forming as a rate-determine step usually result in 13C depletion (due to
kinetic effect)? X represents any element.  In what kind of situations do
reactions result in 13C enrichment?

2. I have Finnigan's delta plus XL and Polaris ion trap both connected to
Agilent GC. The warranty time is over and I'd like to find a good service
contract for the instrument. Does any one know some one who services delta
plus and/or ion trap? Finnigan does provide service but I'd like to have
more options.

Thank you for your help!!!

Ling