Analyte stability in clinical chemistry quality control materials

Maximum stability of analytes in chemistry control materials is desired. Stability testing is customarily performed by manufacturers, both prior to distribution of products and during the period following distribution when the products are in the field. Users and evaluators of such materials periodically have reported on experienced stability of various analytes in distributed manufactured products. A wide variety of both testing protocols and definitions of acceptable stability have characterized published reports on the topic. In the present review, we summarize published studies on control material stability in clinical chemistry, review criteria employed to define instability, and present an approach to evaluating stability of analytes involving both statistical and clinical criteria.