Relative Response Definition

[wanda50]

I have seen 2 definitions for RRF which are RRF=slope impurity/slope substance and the reciprocal. I know there have been discussions here in the past. What is the current thought and are there references?

What I have been doing for my papers is deriving a number and stating the equation and slopes. I realize that different data systems use either RRF or Correction Factor, so I have been leaving it up to those who apply the factors to determine what they actually need.

However, I am tired of arguing with the new generation of report generators (who use bad templates) about how to present this. so, if I have a piece of paper in hand, they will shut up. (I have tried the compendia, googling, etc., and I am frustrated.)

thanks!
Wanda
Lost in the world of API's

[Dan]

Wanda,

You are not the only one confused by this issue. I have seen an inconsistent use of terminology and calculations within the same department at companies. In one instance, one group had a method that gave the RRF equation and they set up in the CDS to multiply by the RRF calculated by that equation. It was 2 years before someone noticed that they should be dividing by the RRF that is in the method. That's 2-years worth of impurity data that had to be recalculated. Luckily, the error was found and corrected before the data got submitted to the FDA.

Help may be on the way:

There was a Stimuli Article in the USP PF about 2 years back that proposed standardization of the equations and terminology. Unfortunately, I am not in the office so I can't go look up the reference and I don't recall the exact issue of the USP PF. I will see if I can find the reference tomorrow when I get my hands on the USP in the library.

Regards,
Dan