Quality control biomarker assays

The effects of the appropriate environmental matrices (soil, water, air, biological - for biomarker or exposure assessment studies) on assay performance must be well characterized and documented. The SOP must also include the degree of quality control necessary to ensure the satisfactory performance of the method. Quality control procedures must address the required sample preparation steps, reagent stability, instrumentation, data handling and analysis. In many immunoassay SOPs that the EPA has reviewed, quality control is totally lacking or minimally addressed particularly for the sample preparations. The Agency can provide direction on what is an appropriate degree of quality control based on the objective of the method. 

In-study validation entails the routine monitoring of the quality control samples to determine whether the analytical method is performing consistently over time and whether data from a particular plate or run are acceptable. In addition, especially for biomarker assays, evaluation of parallelism using incurred samples is carried out to confirm the validity and suitability of the reference standard. 

Sweep, F.C., Fritsche, H.A., Gion, M., Klee, G.G., and Schmitt, M. (2003) Consider ations on development, validation, application, and quality control of immuno(metric) biomarker assays in clinical cancer research an EORTC NCI working group report. International Journal of Oncology, 23, 1715 1726. 

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