Need help and clarification in calculation of GCMS results

[alabsiam]

Hello guys !

I’m actually trying to determine Toluene Conc in some nails colors. I am actually confused in some quantitative calculation using Headspace GCMS. I have done a calibration curve of three STD points; 1,5,10 ppm Toluene. I weighed 0.05 g of the sample and dissolved in Acetone to final volume of 50 mL. Then, I took only 0.5mL of the sample in Headspace Vial even for the three standards and did the running. The result was 8 ppm for my sample
My question is… should I multiply 8 ppm with the final volume 50ml and divide it by sample weight 0.05 to get the actual concentration ?
Is this called Dilution Factor (Final volume/ sample weight g) or Concentration Factor? What’s the difference?

your help would be greatly appreciated

[juanantonio]

Do you enter the dilution factor and sample weight when you run the sample? If not, you are right that you need to multiply by 50 and divided by sample weight. You can check in another way, get the value of slope and intercept and calculate manually and see the difference. You try to remember that equation we learned long time back , y=mx+ or - C where y=Area of your sample, m=slope and C=intercept(it can be + or -) and calculate the value of x, which is the concentration of your sample. then multiply x by 50 and divide by sample weight.