I was calibrating GC on PAINO compound was using split mode 100:1 and 0.5 uL injection volume of diluted sample and it was more that enough for range of 0.001%(10ppm) and Higher concentration . i want to found 0.05ppm(0.000005%) in my sample how i do that?

and can i increase the concentration of the sample (how) ?

and can i change the volume injected or change the split rate if switched What are the calculations of this process ?

And what are usual ways of increasing sensitivity to maximum on GC machines like I have ? (shimadzu 2010 plus).