assay

A set of operations having the object of determining the value of a quantity. In analytical chemistry, this term is synonymous with measurement.
Source:
PAC, 1994, 66, 2513 (Nomenclature for radioanalytical chemistry (IUPAC Recommendations 1994)) on page 2515
PAC, 1993, 65, 2003 (Glossary for chemists of terms used in toxicology (IUPAC Recommendations 1993)) on page 2016