Hi thanks for all your replies. I have finally settled on conditions for the inlet and oven ramp. To answer your question Spuzzin, yes the Florida alkane mix is used for calibration. Currently our guidelines are to measure three collated bands between TPH C10-C36. However, we the range will be extended to C40 soon.

It sounds strange that I got quite a lot of mass discrimination with splitless (both pulse and non-pulse) because there are so many methods out there that use this for TPH/TRH.......Also various split programs also did not help.I also inspected the inlet and thoroughly cleaned it and replaced the gold seal even though the inlet was basically clean to start with. Nevertheless small improvements in the method performance were observed.

I have achieved reasonable performance with the 2:1 pulse split with a starting temperature of 60 degrees. The individual curve RSD's are about 4% for all alkanes up to 32, about 6% for C34-C36 and 10% for C38 and C40. I also focused on the C40/C20 ratio as a performance measure in the end. That ratio was between 0.6-0.7. Hopefully these performance figures remain.