In method validation (ICH and USP) they use specificity of an HPLC method. Can we say that a validated HPLC method is specific for a particular analyte (e.g. pharmaceutical or impurity)? What I know is that we say that it is selective and not specific.
Hi Fuad AL Rimawi,
If you have a sample, with matrix and ingredients (e.g. more than one API), and you can only detect one API. That method is specific for that API.
If you can separate and detect more ingredients with out interferences, than that method is selective.
So yes, selective and specific is not the same and yes a validated method can be specific for one analyte, as you mentioned above.
I hope that it was helpful?
Regards
Matthias
Hi Fuad AL Rimawi,
If you have a sample, with matrix and ingredients (e.g. more than one API), and you can only detect one API. That method is specific for that API.
If you can separate and detect more ingredients with out interferences, than that method is selective.
So yes, selective and specific is not the same and yes a validated method can be specific for one analyte, as you mentioned above.
I hope that it was helpful?
Regards
Matthias
Hi,
the terms “selectivity” and “specificity” both give an idea of the reliability of the analytical method. Selectivity refers to the ability of the method to discriminate a particular analyte in a complex mixture without interference from other components. In the other hand, specificity can be considered as the ultimate selectivity, i.e. 100% selectivity (or 0% interferences).
Regards,
Vitor Spinola.
Further reading on this important topic can be found:
Selectivity in analytical chemistry,
by Vessman, Jorgen; Stefan, Raluca I.; Van Staden, Jacob; Danzer, Klaus; Linder, Wolfgang; Burns, Duncan Thorburn; Fajgelj, Ales; Muller, Helmut.
In Pure and Applied Chemistry (2001), 73(8), 1381-1386. DOI:10.1351/pac200173081381
The correct use of the term selectivity and its clear distinction from the term specificity are discussed. A definition of selectivity is given, and it is recommended that the use of this term be promoted and that the use of the term specificity be discouraged.
The definitive text on the this subject suggested by Olle is an IUPAC recommendation which could be accessed free of charge at the Pure and Applied Chemistry journal website: http://pac.iupac.org/publications/pac/73/8/1381/
Among the parameters demonstrating the validity of the proposed HPLC assay, its Selectivity is defined as “the ability of differentiating and quantifying the analyte in the presence of other components from its matrix”. Specificity is defined as “the ability to assess unequivocally the analyte in the presence of components which might be expected to be present.” The terms selectivity and specificity are often used interchangeably. Inconsistent with ICH, the term specific generally refers to a method responding to a single analyte only, while the term selective refers to a method which provides responses for a number of chemical entities that may or may not be distinguished from each other. If the response is distinguished from all other responses, the method is said to be selective.
Hii,
As per ICH guideline "Specificity" can be defined as the ability of the method to specifically separate the particular API or analyte in the presence of other components.
Hence, specificity can be divided into two parts: Matrix interference and separation selectivity.
Under matrix interference, the enhacing or quenching effect of the matrix (e.g., formulation buffer) is checked and for separation selectivity the sample is spiked with the known amount of impurities and checked whether the method is able to separate the API in the presence of other impurities.
Thanks,
Shalini
As highlighted by Gary Christian, in his
book on analytical chemistry, a clear
distinction should be made between
selective and specific (8). Few analytical
methods including chromatographic ones
are truly specific. The recommendation
made by IUPAC that specificity is the
ultimate of selectivity is, therefore, to be
promoted and selectivity should be
favoured in all cases in which good
analytical chemistry is presented.
The bottom line is that when dealing
with most chromatographic methods the
use of the term specificity deludes both the
chromatographer from the perspective of
poor analytical science and the user of the
data by making them believe they are
getting more than is actually being delivered.
Ref: http://www.rdmcdowall.com/htmlupload/14042/491?T=633459422620230000.LC/GCINTERNATIONAL
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