The random fluctuations occurring in a signal that are inherent in the combination
of instrument and method.
Source:
PAC, 1989, 61, 1657
(Nomenclature for automated and mechanised analysis (Recommendations 1989))
on page 1663
See also:
PAC, 1995, 67, 1745
(Nomenclature, symbols, units and their usage in spectrochemical analysis-XI. Detection
of radiation (IUPAC Recommendations 1995))
on page 1750