Chromatography Forum

hi, everyone.
who can tell what is he difference between selectivity and specificity in bioanalysis?

thanks!

In general (and I cannot be sure that this applies to bioanalysis) a specific analysis detects only the target analyte. A selective analysis detects the target analyte plus some others, usually the specific response for the target is higher than for other compounds.

A specific analysis is extremely selective.

Peter

And if you have better selectivity, then you can usually get better specificity.

There is a continuum of detector selectivity, ranging from teh so called universal detectors that detect almost everything to a very selective detector that detects only a single analyte. Selective and specific are poorly defined points on that scale. To use a common example, the electron capture detector used in gas chromatography has sensitivity related to electron capture cross section. It is more sensitive for compounds with a large electron capture section, and is often used for organochlorine pesticide analysis because it has selectivity for these compounds. It still has some response for high levels of hydrocarbon, and this is expressed as a ratio. Typically to get equal response for a hydrocarbon and a pesticide you need 1 pg of pesticide and 1 ug of hydrocarbon.

There are thermionic detectors that are specific for halogens, and have essentially no response to hydrocarbons. These are considered haolgen specific, while an ECD is halogen selective.

Simply put, selectiveity is most used in analytical community, while specificity is preferred by bio-analytical field. In clinical area, specificity also relates to faulse negative rate of an assay.

I think in bioanalysis..selectivity and specificity are same.....
6 lloq from different patient plasma......

there is a debate still about use of the words, I like - selectivity is 100% specificity