Inject known concentrations of the gas (say, 99%, 50%, 10%) and obtain the peak areas for this concentration. Plot a calibration graph i.e. concentrations versus corresponding peak areas. Fit the points with a linear curve. Now, you have a calibration equation which is the equation of the linear curve. Inject unknown concentrations, obtain peak areas. Use the calibration equation to get the unknown concentration. I have attached a sample calibration graph.

https://www.gmu.edu/depts/SRIF/tutorial/gcd/calcurve.gif

Did you Google?

Your answer is here on Research Gate:https://www.researchgate.net/post/How_can_I_calculate_the_concentration_from_a_gc_ms_chromatogram_which_is_having_retention_time_and_peak_area_only

Inject known concentrations of the gas (say, 99%, 50%, 10%) and obtain the peak areas for this concentration. Plot a calibration graph i.e. concentrations versus corresponding peak areas. Fit the points with a linear curve. Now, you have a calibration equation which is the equation of the linear curve. Inject unknown concentrations, obtain peak areas. Use the calibration equation to get the unknown concentration. I have attached a sample calibration graph.

https://www.gmu.edu/depts/SRIF/tutorial/gcd/calcurve.gif

thank you Anjana Kadni...I already plot calibration curve and try your method. Because I have hundreds of data, I was wandering is there any other way. And I just realize that we can use 'TREND' formula in microsoft excel. However, thank you very much. It is very helpful.

It all depends on whether you need the precise concentration, or relative concentration.

If relative, then you assume the response to the detector for each peak is the same, so the concentrations are the relative % of the total response. So you have 48,000/318,000 = % of the minor component which is 15%, and that means the major component is 85%.

If you want precise concentrations, then it requires determining the response factors, and using standards.