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An assay (analysis) is never an isolated process, as it must be accompanied with pre- and post-analytic procedures. Both the communication order (the request to perform an assay plus related information) and the handling of the specimen itself (the collecting, documenting, transporting, and processing done before beginning the assay) are pre-analytic steps.
The assay is a solid-phase type of enzyme immunoassay (EIA) to detect the presence of a ligand (commonly a protein) in a liquid sample using antibodies directed against the ligand to be measured. ELISA has been used as a diagnostic tool in medicine, plant pathology , and biotechnology , as well as a quality control check in various industries.
A NASA illustration of a lateral flow assay. A lateral flow test (LFT), [1] is an assay also known as a lateral flow immunochromatographic test (ICT), or rapid test.It is a simple device intended to detect the presence of a target substance in a liquid sample without the need for specialized and costly equipment.
Direct assay In a direct assay, the stimulus applied to the subject is specific and directly measurable, and the response to that stimulus is recorded. The variable of interest is the specific stimulus required to produce a response of interest (ex. death of the subject). [6] [12] Indirect assay
Multi-step assays are often called separation immunoassays or heterogeneous immunoassays. Some immunoassays can be carried out simply by mixing the reagents and samples and making a physical measurement. Such assays are called homogeneous immunoassays, or less frequently non-separation immunoassays.
Molecular diagnostics uses in vitro biological assays such as PCR-ELISA or Fluorescence in situ hybridization. [19] [20] The assay detects a molecule, often in low concentrations, that is a marker of disease or risk in a sample taken from a patient. Preservation of the sample before analysis is critical.
Enzyme assays can be split into two groups according to their sampling method: continuous assays, where the assay gives a continuous reading of activity, and discontinuous assays, where samples are taken, the reaction stopped and then the concentration of substrates/products determined.
Assay offices are institutions set up to assay (test the purity of) precious metals. This is often done to protect consumers from buying fake items. Upon successful completion of an assay (i.e. if the metallurgical content is found be equal or better than that claimed by the maker and it otherwise conforms to the prevailing law) the assay offices typically stamp a hallmark on the item to ...