what is the need of calulation of RRF of impurity in HPLC
analysis?
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Answer / ravi
we are analysing the sample at one perticular wavelenght
and it is not possible that all the impurities present in
the sample are having same labda max, to bring the response
of all these impurities to same level we are applying RRF.
| Is This Answer Correct ? | 55 Yes | 6 No |
Answer / ramesh babu
Generally RRF will calculate in impurity analysis. The
impurity standards are very cost effectives and some times
not avalible. It is not possible to use the impurity
standard at each time of the impurity analysis.During the
method development time we need to calculate RRF against
with standard.
| Is This Answer Correct ? | 44 Yes | 9 No |
Answer / vijayalakshmi
To know the exact % of impurity with respect to the main
peak concentration
| Is This Answer Correct ? | 24 Yes | 16 No |
Answer / chromatographer
Dear all RRF is very important tool for the exact impurity %
calculation.As per the guidelines we have to select the
wavelength for the compound at which its shows lemda max.But
in case of RS most of the impurities doesnt follow the
same.So in order to equilibirate treir response with respest
to main compound at a perticuler wavelength its required.In
RRF determination we do injent the same concentration of
impurity and compound, and devide the area of impurity with
area of compound.
| Is This Answer Correct ? | 8 Yes | 2 No |
Relative Response Factor (RRF) is an analytical parameter used in chromatographic procedures to control
impurities/degradants in drug substance and drug product. RRF is used to correct the difference in
detector response of impurities with analyte peak. RRF is established by slope method with linear range
of solutions. Different Pharmacopoeias refer the term RRF differently.
As per United States Pharmacopoeia (USP) The Relative response factor, is the ratio of the responses of
equal amounts of the Impurities and the drug substance1
. USP refers RRF as Correction factor or
Response factor or Relative response factor.
As per European Pharmacopoeia (Ph.Eur) The Relative detector response factor, commonly referred as
Response Factor, expresses the sensitivity of a detector for a given substance relative to a standard
substance. The correction factor is reciprocal of the response factor2
. Ph.Eur refers RRF as Correction
factor or Response factor.
As per British Pharmacopoeia (BP) The Response Factor is a relative term, being the response of equal
weights of one substance relative to that of another in the conditions described in the test3
. BP refers RRF
as Response factor.
Establishment of RRF is required to avoid the stability issues with standards, to reduce the cost
on preparation of Impurity Standards, to reduce Maintenance of Impurity Standards, due to the lack of
donation of Impurity Standards, difficulty in synthesis and isolation of Impurity Standards, for
convenience and time saving. Relative Response factor (RRF) is used in different stages: Phase 1 to
Phase 4 studies, in drug purity tests, Mass balance tests, in limit tests, In stability indicating methods etc.
| Is This Answer Correct ? | 5 Yes | 1 No |
Answer / laura
Hi,
When a different marker is used to find out which impurity is seen in the chromatogram due to not being availble, and a really similar compound is used (in this case the salt ) how can I calculate the RRF of the compound which was not available in regard to the one that was tested? I calculated the RRF of the compound tested, but how can I extrapolate to the one I am looking for?
Many thanks in advance,
| Is This Answer Correct ? | 0 Yes | 0 No |
Answer / pramod_ganji
In olden days when manual injectors were used the injection
volume used to vary and hence the response, so to eliminate
this problem internal standards were sujested. Relative
Response Factor (RRF) is the best choice as same amount of
internal standard is added to standard and sample solution.
So the ratio will remain constant irrspective of change in
injection volume.Over the period auto injectors have
replaced the manual ones but still this method is one of
the choice for method development chemists and hence RRF is
still in use.
In case of impurity determination by HPLC Area percent is
one of the quantitaion method when standards are not
available, not to be confused with RRF.
| Is This Answer Correct ? | 4 Yes | 9 No |
Answer / chalapathi rao.n
when apply RRF we obtained exact real peak area% in your sample.
| Is This Answer Correct ? | 3 Yes | 13 No |
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