Resolution and resolving power
IUPAC 2013 Reccommendation
The IUPAC definition of resolution in mass spectrometry expresses this value as m/Δm, where m is the mass of the ion of interest and Δm is the peak width (peak width definition) or the spacing between two equal intensity peaks with a valley between them no more than 10 % of their height (10 % valley definition) [1]. Resolving power in mass spectrometry is defined as the ability of an instrument or measurement procedure to distinguish between two peaks at m/z values differing by a small amount and expressed as the peak width in mass units [2]. Mass resolving power is defined separately as m/Δm in a manner similar to that given above for mass resolution [3]. These definitions of mass resolving power and resolving power in mass spectrometry are contradictory, the former is expressed as a dimensionless ratio and the latter as a mass. The definitions for resolution in mass spectrometry and resolving power in mass spectrometry come from Todds 1991 recommendations [4], and the definition for mass resolving power comes from Beynons 1978 recommendations [J. Beynon. Pure Appl. Chem. 50, 65 (1978)]. Beynons work contains no definition for mass resolution.
Alternative definitions for resolution and resolving power in mass spectrometry have been proposed [5][6]. It has been suggested that resolution be given by Δm and resolving power by m/?m; however, these definitions are not widely used.
The majority of the mass spectrometry community uses resolution as defined by IUPAC. The term resolving power is not widely used as a synonym for resolution. In this document, the IUPAC definition of resolution in mass spectrometry remains in place. The definition of resolving power has been adapted from the current IUPAC definition of mass resolving power.
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