Which of the following is NOT one of the steps involved in the validation of assay?

The process of validating an assay typically involves several critical steps designed to ensure that the assay produces reliable and accurate results. Method validation involves confirming that the procedure used is appropriate for its intended purpose, ensuring the methodology meets regulatory standards and is suitable for obtaining results. Instrument performance checks ensure that the equipment used in the assay operates according to specifications and delivers consistent results under defined conditions. Assay calibration involves adjusting the assay to align with standards or controls to ensure accuracy in the measurement of the analyte.

Composition analysis, while important in some contexts, does not fall under the specific steps of assay validation. Instead, it refers to determining the components or ingredients of a sample, which is not a part of the validation process itself. The validation steps are aimed at confirming the method's reliability, the performance of the instruments, and the calibration of the assay, rather than assessing the chemical makeup of the sample being tested. Thus, it is the step that does not align with the validation process in this context.