specific

in analysis
https://doi.org/10.1351/goldbook.S05788
A term which expresses qualitatively the extent to which other substances interfere with the determination of a substance according to a given procedure. Specific is considered to be the ultimate of selective, meaning that no interferences are supposed to occur.
Source:
PAC, 1983, 55, 553. 'Recommendations for the usage of selective, selectivity and related terms in analytical chemistry' on page 555 (https://doi.org/10.1351/pac198855030553)