Could someone please explain the difference between them? Many thanks!

Dear Anonymus;

Unfortunately the two terms are often used interchangeably. Selectivity usually applies to a preference or special affinity for a type of compounds, such as , "selective for ketones". Specific should strictly be used when only one compound produces the desired response, such as "specific for Benzene".

Chromatographic methods are selective, but they are rarely specific.

I hope this helps;

Benjamin

Dear Bemjamin:

Is there any ICH, USP or FDA definition to them?

DEar Anonymus;

I found this definition for Specificity in the ICH web page. I could not find the same for selectivity.

Benjamin


Validation of Analytical Procedures

GLOSSARY

2. SPECIFICITY
Specificity is the ability to assess unequivocally the analyte in the presence of
components which may be expected to be present. Typically these might include
impurities, degradants, matrix, etc.
Lack of specificity of an individual analytical procedure may be compensated by other
supporting analytical procedure(s).
This definition has the following implications:
Identification: to ensure the identity of an analyte.
Purity Tests: to ensure that all the analytical procedures performed allow an
accurate statement of the content of impurities of an analyte, i.e.
related substances test, heavy metals, residual solvents content, etc.
Assay (content or potency):
to provide an exact result which allows an accurate statement on
the content or potency of the analyte in a sample.