Abstract: Chromatography apparatus capable of deriving optimum conditions for an analysis includes data processing means which comprises calculating means (20) to be supplied with initial conditions (24) entered by the chromatographer and which may be calculated from the results of an initial chromatogram, limits and requirements (25) relating to limiting values of parameters of the chromatograph and to the required selectivity and sensitivity of the analysis and which are entered by the chromatographer, and the detector time constant (23) which is selectable, within limits, by the chromatographer. The data processing means also includes a column data base (21) which contains data specifying the available separating columns and a detector data base (22) which contains data specifying the available detectors.The optimization criteria are the minimum possible analysis time coupled with adequate peak separation and sensitivity.