A quantity of material which is assumed to be a single population for sampling purposes.
Sources:
PAC, 1988, 60, 1461. 'Nomenclature, symbols, units and their usage in spectrochemical analysis-X. Preparation of materials for analytical atomic spectroscopy and other related techniques (Recommendations 1988)' on page 1463 (https://doi.org/10.1351/pac198860091461)
PAC, 1990, 62, 1193. 'Nomenclature for sampling in analytical chemistry (Recommendations 1990)' on page 1201 (https://doi.org/10.1351/pac199062061193)