Materials, placement, criteria, and triggers

Select documented, matrix-appropriate materials across the applicable range. The number of levels, use of duplicates, and same-shift review are laboratory/procedure decisions driven by intended use and the approved plan, not universal requirements. A dilution is used only when the manufacturer’s instructions permit it and it is appropriate for the method.

A multi-level design can reveal behavior a sparse design may miss, but the approved procedure sets the levels and replicates. Assess commutability when using processed comparison material: an assigned value alone does not make it behave like patient specimens.

Acceptance criteria are documented for the procedure. In this glucose case, ±8% or ±6 mg/dL, whichever is greater, is a case criterion; the absolute allowance governs low concentrations and the percentage allowance governs higher concentrations. It is not a universal calibration-verification rule.

If material is noncommutable, stop the unsupported comparison and follow the approved alternate plan. If no matrix-appropriate material is available, escalate before release; do not silently use an unsuitable material to support go-live.

Select the material, acceptance criterion, and response route from the applicable procedure before deciding a result supports release.