A sample taken, prepared and stored in an agreed upon manner for the purpose of settling a dispute. The agreement usually extends beyond the sample to the basis for reaching a decision (e.g. quantity of material from which taken, use of a third party and criteria serving as the basis for acceptance, rejection or economic adjustment). The term 'reference sample' has been used in this context but this term more properly should be used in conjunction with a 'reference material' or 'reference standard' which has a true or assigned value for a constituent or property. One of the characteristics of a reference material or reference standard is that it must have a negligible sampling error between test portions.
PAC, 1990, 62, 1193. 'Nomenclature for sampling in analytical chemistry (Recommendations 1990)' on page 1203 (https://doi.org/10.1351/pac199062061193)