Overcoming retention time shifts as a source of error in HPLC analysis.

When used for physiologic fluid analysis, shifts in retention times, even at constant flow rates, can cause integrators to function inadequately as tools for peak identification and thus result in concentration errors. A system capable of data collection, identification, quantification, and long-term storage that primarily uses retention times only for identification of elution sequence is described. Operator identification, aided by manipulation of x and y coordinates of the chromatograph, enhances positive identification of compounds for the experienced chromatographer.