in analytical chemistry
  1. (for bulk materials): Each of the single, large portions of material pre-existing either in space (e.g. bags, bales, drums) or accumulated during a fixed time (e.g. discharge from a conveyor belt) or formable as increments by a sampling device. Segments may be actual or conceptual.
    PAC, 1990, 62, 1193. (Nomenclature for sampling in analytical chemistry (Recommendations 1990)) on page 1202 [Terms] [Paper]
  2. The set of samples which can be analysed between two successive calibrations. A segment includes samples, control materials and blank samples. This term is of particular importance in clinical chemistry.
    PAC, 1989, 61, 1657. (Nomenclature for automated and mechanised analysis (Recommendations 1989)) on page 1661 [Terms] [Paper]