Tako referenčni ali ojačani material, ki vsebuje znane količine analita na ali blizu dovoljene ali odločitvene meje (neskladen kontrolni vzorec - pozitivna kontrola), kot tudi skladni kontrolni materiali (negativna kontrola) in slepi reagenti naj po možnosti gredo skozi vse faze preskusnega postopka istočasno z vsako serijo analiziranih preskušanih vzorcev.
Reference or fortified material containing known amounts of analyte, at or near either the maximum permitted limit or the decision limit (non-compliant control sample) as well as compliant control materials and reagent blanks should preferably be carried through the entire procedure simultaneously with each batch of test samples analysed.