split-sample test­ing

Introduction. It was shown by a number of studies that characteristics of materi­als used for quality control (QC) are not identical to the natural samples charac­teristics. Nevertheless, QC materials re­main irreplaceable for daily variance as­sessment, but the information provided by QC measurements could be insuffi­cient if different equipment for the analy­sis of the same analyte is in use at the same laboratory.