Hello everybody,
I'm mainly concerned with GC/C/IRMS analysis of steroids extracted from
human urine. The main purpose of this is to detect synthetic endogenous
substances that are prohibited in sports.

(Recently there was a discussion on this list, where the literature
related to this topic has been reviewed extensively)

Our machine is a HP GC 5890 connected to a FINNIGAN DELTA C via a FINNIGAN
combustion interface II.

Now here is my question ...

Has anybody experience with the effects of on-column injection in a
configuration similar to our device? Is it possible to use on-column
injection routinely with an autosampler?

There seems to be some fractionation in the injector even in
splitless mode. Another reason why I want to try on-column is that we
often have to deal with very low amounts of substance (~10-15ng).

Is there any significant influence on peak shape and on chromatographic
resolution or are these parameters basically limited by the combustion
interface? We have some problems in achieving complete baseline separation
for some isomers.

Many thanks in advance!


        Uli Flenker
        Institute of Biochemistry
        German Sports University Cologne
        Carl-Diem-Weg 6

        50933 Cologne / Germany

        Phone 0049/0221/4982-493