Which of the following is NOT a requirement for quality control (QC) materials?

In quality control for clinical chemistry, the materials used must meet specific criteria to ensure accurate and reliable test results. The requirement of being independent of the method of assay is not a necessary condition for QC materials.

Quality control materials are typically designed to simulate the biological specimens they are intended to reflect. This means that the matrix of the QC material should closely match that of patient samples to provide good correlation during testing. Additionally, long-term stability is crucial to ensure that the QC materials maintain their properties over time, allowing for consistent performance during testing periods.

Another important aspect is that the concentration of analytes in the QC materials should reflect the clinical range, which helps to ensure that the QC can effectively monitor the performance of assays in real-world conditions.

However, analyte concentration being independent of the assay method is not a standard requirement. Many QC materials can be influenced by the method of assay used for testing; this variability is often accounted for in the quality control process. Hence, the requirement that analyte concentration must be independent of the method is not applicable, making it the correct answer to the question.