Chromatography Forum

WHAT IS NEED TO CALCULATE RRF IN HPLC ANALYSIS

No need to shout
General way is to determine calibration lines of the reference substance (in pharmaceutical analysis usually the API) and the analyte(s) (usually related substances). RRF is calculated by dividing the slopes of the calibration lines (slope reference/slope analye if I remember correctly, but it might be the other way round...).
Another way would be to determine the responses (aka peak areas in HPLC) and calculate the RRF directly from it. But you should do this at several concentrations covering the working range to make sure the RRF is constant. Since you should use several concentrations anyway, the "calibration line approach" depicted above would be my way to go...

WHAT IS NEED TO CALCULATE RRF IN HPLC ANALYSIS

BUT WHY RRF IS NEEDED ?

BUT WHY RRF IS NEEDED ?

Different compounds have different response factors. If you have individual calibration curves for each compound, then RRF is not needed.

At times in the case of an impurity or related substance, you may not be making a standard and calibration curve of the compound. Instead you reference it's area in relation to the API, and then using the RRF can calculate out the concentration of the peak.