relative detection limit

(Often incorrectly referred to as sensitivity). Smallest amount of material detectable (3σ-criterion) in a matrix relative to the amount of material analysed — given in atomic, mole or weight fractions.
PAC, 1979, 51, 2243 (General aspects of trace analytical methods - IV. Recommendations for nomenclature, standard procedures and reporting of experimental data for surface analysis techniques) on page 2247