Hello Ahmed

Simply spoken:  yes, because if you dont have a standard, you start with the purity you have as a standard until you get fitting references. Maybe you have chance to estimate a purity over f.e. NMR so you can relate the result to your measurements.

Other possibility could be to relate the Area to a specific Absobtion constant ,if known and if you use UV-Detection, this could give you a direct calculation at a specific wavelength. 

good luck