Yesterday was another one with instrument time and things went well. I am still tweaking a couple of parameters (mainly injection conditions), but I am already collecting data (and I see quite a few species – some of them confirming earlier results). I am still struggling with two aspects of the measurements (that have to do with the splitless injection):
(1) Column bleeding
(2) Decay of fiber signal after desorption
I can reduce significantly (1) by choosing a short time until purging (1.5 min), but obviously my signals suffer. If I go by the typical desorption time of 5 min (resulting in purging after 5 min as well), I have a lot of column bleeding, which is not necessarily overlapping with analyte peaks, but messung up my chromatogram considerably.
The same is true for (2) – after desorption I observe a large peak of (mainly) water desorbing from my fiber. By purging early, I can avoid that some of the water is loaded onto the column, resulting in a acceptable baseline earlier (and thus making this timeframe available for additional peaks), but of course my sensitivity suffers.
Well, probably, it is going to be somewhere in the middle, although I lack a good selection criterion so far. But on the whole, it is going well.
