Chromatography Forum

Hello every one I need a basic help, ...How to calculate back my uknown sample, I am new to GC analaysis ...
Story is :
1, I extracted lipids with petrolium either and saponified to get residue of the unsaponifiable matter for e.g a total of 0.09 grams was separated and this was diluted in 2ml dichloromethane.( this is my sample to run in GC)
2. I have cholesterol with 1200ppm, Sitisteriol with 1500ppm for the internal standard to prepare and I have a total volume of 1.5ml vial to fill for the GC. what I did was I prepared 6 factors with dilution factor of , 5x, 7.5x, 15x, 25x, 75x, 150X,
that is is 300 +1200=1500ul that is 5x dilution factor
200 + 1300= 1500ul
100 + 1400= 1500ul
60 + 1440= 1500ul
20 + 1480= 1500 ul
10 + 1490= 1500ul .....150x dilution factor... in the GC soft ware i can see that some of the peaks are in the range but some of them are bigger peak that is big area so I still need to dilute my samples but now at the end i dono how to calculate back my unknown samples concentration , would u plz suggest anything or give me simple example to flow...

Regards,
Z.

zewo,

As I quickly read over your post, I am not exactly cleare on exactly what you have in your solutions. But, briefly you need a graph (and in a spread shet you can calculate a regression also) and that graph has analyte concentration on one axis and response on the other. If you use an internal standard, you use the ratio of peak area of the analtye to the internal standard as the response.

Let me know if that helps.

Don