Chromatography Forum

Dear Experts

I need to know how to calculate response factor scientifically of impurities in API .

Example : I have taken following mixture .
1. 93 g main substance ( API )
2. 05 g Impurity 1
3. 02 g impurity 2

So now I think that I have taken 5 % imp. 1 & 2 % imp. 2 in above mixture . After injection I found Imp.1 is 8 % & Imp. 2 is 1 % on HPLC chart paper .

Now can any body guide me how to calculate scientifically . I know Imp. 1 shows 1.6 times higher than actual & Imp.2 shows 0.5 times less than actual .

Thanks in advance .

S.M.,

Did you check the linearity from the 100 % to the detection limits of the Imps? It doesnt make sence to calculate response factors for peaks obtained at several times of the possible specification limit as long as you are not sure about the linearity.
Your calculation is basically correct.

Alex