In
atomic spectroscopy, flux of mass of sample divided by the flux of mass of solvent blank, measured under the same conditions, expressed as a percentage.
Source:
PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 727 (https://doi.org/10.1515/pac-2019-0203)