A sample or a known fraction of the parent population in which the analyte has been
isolated or (usually) concentrated before being submitted to the laboratory. If the
isolation or concentration occurs in the laboratory, the procedure is usually considered
part of the preparation of the
test sample from the
laboratory sample (in-laboratory processing).
Source:
PAC, 1990, 62, 1193
(Nomenclature for sampling in analytical chemistry (Recommendations 1990))
on page 1204