Cannot find some VOC Analytes (Static Headspace)


I am having some trouble to reach the equilibrium/find injected analytes with VOC Gas Injection.

We use static headspace (Gerstel Application, incubation for half hour in 20mL Headspacevials, 140°C in an Agitator, after that we use cold trapping on Column with Gerstel KAS) and Agilent GC-MS sytem in Scan-Mode (with Sil-624 column).

I tried to heat up the Agitator a little bit more but it was not a good idea (the matrix modifier started to boil and I have not found the analytes eighter).

I used 10mL of matrix modifie (Water with pH 2 (ajusted with phosphoric acid), saturated with NaCl) and spiked the VOC Analytes in. 

From 40 Analytes I have not found the following (all of them have a higher BP compared to the substances without throuble (e.g. DCM, Toluene):

o-Kresol CAS 95-48-7
2-Methoxypropylacetate CAS 70657-70-4
Acetophenone CAS: 98-86-2
m-Kresol CAS 108-39-4
p-Kresol CAS 106-44-5

Has anyone a idea how I can find these Analytes?

Thanks a lot!

Was this helpful?