By JM on Wednesday, August 4, 2004 - 01:48 am:
Dear all,
What is the difference between Response Factor(RF) and Relative Response factor ( RRF)and how to calculate?
By Linda on Wednesday, August 4, 2004 - 07:45 am:
RF=Concentration of analyte/peak height or area
RRF=RF of analyte/RF of internal standard
By JM on Wednesday, August 4, 2004 - 10:27 pm:
To calculate % impurity will this RRF should be Multiply or devided?? I am bit confused as USP mulitpy this RRF and others divide???
By Gina Kamins on Friday, August 6, 2004 - 12:17 pm:
Must think in terms of Units- use the good old factor-label method of calculating! Some people calculate RRF as the response of the impurity divided by the response of the reference peak. In this case, the impurity is on the top, therefore you would need to divide because you are, in essence, converting area of an impurity to an area that can be directly calculated against a standard:
For example:
If:
1mg/mL of impurity = 2000 area counts
1mg/mL of reference peak = 1000 area counts
RRF = 2000/1000 = 2 (because it absorbs twice as much for the same concentraion).
Therefore, to quantitate the impurity vs. the reference peak, you would need to DIVIDE your impurity area by 2.
"Corrected" imp area = RF reference peak /RF imp
Hope this helps!
Word of caution- I've worked at 2 companies and they calculate RRF completely opposite!