As the field of multi-dimensional separations has developed, terminology has changed somewhat, causing trouble in reading the literature. This list of terms reflects currently accepted terms in the literature, with our own preferences emphasized in ambiguous cases.

This list of terms and defintions is an updated and slightly modified version of the suggestions made by Marriott, Schoenmakers, and Wu in *LCGC Europe*.

Abbreviations

- LC-LC – online or “heart-cutting” two-dimensional liquid chromatography
- LC x LC – comprehensive two-dimensional liquid chromatography
- sLC x LC – selective comprehensive two-dimensional liquid chromatography

Symbols

^{1}D – this abbreviation is used as a modifier indicating ‘first dimension’. For example,^{1}D column is used to communicate the idea ‘first dimension column’^{2}D – a similar abbreviation is used to denote the ‘second dimension’

- 1D – different from the abbreviations above, this denotes a one dimensional system
- 2D – abbreviation for a two dimensional system

^{1}*t*_{r}– the retention time for a given peak in the first dimension

^{2}*t*_{r }– the retention time for a given peak in the second dimension

^{1}*t*_{M}– “dead” time of the first dimension conditions

^{2}*t*_{M}– “dead” time of the second dimension conditions^{1}*k*– retention factor of a given eluting from the first dimension column

^{2}*k*– retention factor of a given eluting from the second dimension column^{1}*N*– the number of theoretical plates of the first dimension column^{2}*N*– the number of theoretical plates of the second dimension column^{1}*N*– the number of effective plates of the first dimension column_{eff}

^{2}*N*– the number of effective plates of the sec0nd dimension column_{eff }

^{1}*W*_{1/2}– peak width at half height of a peak eluting from the first dimension column

^{2}W_{1/2}– peak width at half height of a peak eluting from the second dimension column^{1}R_{s}– resolution value of a peak eluting from the first dimension column^{2}R_{s}– resolution value of a peak eluting from the second dimension column^{1}n_{c}– peak capacity of the first dimension column, note that the use of subscript c is used to avoid confusion with the n that is sometimes used for theoretical plates^{2}n_{c}– peak capacity of the second dimension column