[parinaz22]

Hi my friends
I have a question about GC
The table shows chromatographic data for the analysis of benzene using an ethylbenzene internal standard. What is the benzene concentration of sample in μg/ml?
                                            standard  sample
[benzene]  μg/ml                        50           -
[ethylbenzene]  μg/ml                 10          10
benzene peak area mV.s              2500    2500
ethylbenzene peak area mV.s       1000     500

Thanks

[Arkcon]

I'd like to welcome you, parinaz22:, the the Chemical Forums but I'd like to ask you to read the Forum Rules{click}.  We like to help you learn to help yourself.  Can you begin to show us your attempt?

[parinaz22]

Thanks dear Arkcon for your consideration
I searched in the Internet. Although, I know the answer is 100, I could not understand how to calculate it. I found some equations and some example. But I do not know how to use them.

[Arkcon]

OK, that's a start, can you copy the formula here?  Can you replace some terms in that formula with numbers that you have?  It might even work the first time, but I'm glad you're also trying to find out why the formula works.

[parinaz22]

I know that the concentration is calculated by comparing the peak area of the analyte in the sample with the peak area of the standard of a known concentration. I have to use the area ratio between the analyte and the internal standard.
Relative Response Factor (RRF) = Response Factor A / Response Factor B
Concentration A = Peak area A / Peak area B   x   1 / RRF   x   Concentration B
But, I do not know how to use them.
Thanks