Actually RRF establishment required For Relatives Substances

Why because in Rs Sample having so many components like impurities,Degradents and main Analytes etc..so all components does not have same wavelength but we are fix one particular wavelength for all peaks. so inthat wavelength some peak response high and some peak response low.so that reason only we are established RRF and impurities also expensive so every time we can't purchase.so once established the RRF that factor used for RS calculation