By Anonymous on Wednesday, July 16, 2003 - 07:08 am:
i would like to know related to RRF , RF , Correlaton Factor wheather they all are same or has difference how to take them in calculation , and what factors it depends , mobile phase , diluent , or its constant for one method once determined, or its depends on system to system , means waters detector gives different RRF And agilent gives different . is it theoritically or may be in praticle.
By tom jupille on Monday, July 21, 2003 - 01:24 pm:
There is a lot of sloppy terminology out there.
"Correlation Factor", for example, has been used in the literature to refer to the ratio of peak size (area or height) to the amount (mass or concentration) injected. It has also been used to refer to the "coefficient of correlation" (r), a measure of scatter in your data.
Similarly, "RF" ("response factor") has also been used to refer to the ration of peak size to amount injected, as well as to the relative migration distance of spots in planar chromatography.
The bottom line here is that you must examine the method or paper carefully to find the author(s)' definition of the terms.
Having said that, assuming you are talking about quantitative analysis, all three terms can mean approximately the same thing: the ratio of amount of peak size to amount of analyte. This allows a wide variation in units (peak size may be either area or height, for example, while amount of analyte may be mass, moles, or even concentration). Assuming further that you are using consistent units (e.g., microvolt-seconds for peak area and micrograms for analyte mass), a response factor will be valid *only* on the exact instrument and under the exact conditions for which the calibration (determination of the response factor) was carried out. If you change *anything* (detector, column, mobile phase batch, flow rate, etc.), then you must re-calibrate.
-- Tom Jupille / Rheodyne - LC Resources Group
By Anonymous on Wednesday, July 23, 2003 - 02:58 am:
So i Woluld like to know why USP , Ep and other pharmacopeia gives RELATIVE RESPONSE FACTOR FOR THE METHOD AS IT WILL BE CHANGED FROM ONE MAKE OR INSTRUMENT TO OTHER MAKE OF INSTRUMENT SO IS IT SO MUCH NEGLIGIBLE THAT WE SHOULD NOT CONSIDER THIS FACTOR AT THE TIME OF METHOD DEVELOPMENT.
By Anonymous on Wednesday, July 23, 2003 - 05:31 pm:
Ask USP and EP
By Anonymous on Tuesday, July 29, 2003 - 01:24 am:
Yes, it is always better to have one-to-one calibraion methods , instead of depending on RRf values.