Immunoassay quiz Flashcards
What are radioimmunoassay (RIA) labels
radioactive labels with emission properties
What is competitive RIA
antigen is labeled, known as tracer
What is non-competitive RIA
antibody is labeled
How do enzyme labels work
enzyme catalyzes substrate molecules and amplifies signal
What are fluorescent labels
compounds that absorb radiant energy at one wavelength and emit radiant energy at a longer wavelength
What is a common fluorescent label
fluorescein isothiocyanate - green color
What are chemiluminescent labels
compounds that emit photon of light in response to chemical reaction
Common chemiluminescent label
acridinium esters
Principle for competitive immunoassay
amount of antigen is indirectly proportional to amount of signal
Principle for non competitive immunoassay
amount of antigen is directly proportional to amount of signal
Principle for homogenous immunoassays
do not require separation of of unbound complexes from bound
Principle for heterogenous immunoassays
require separation of unbound complexes, often using a solid phase such as a well or beads
What is enzyme multiplied immunoassay technique (EMIT)
automated method used for drug detection; measured drug level is inversely proportional to enzyme activity detected
Components of enzyme immunoassays (EIA)- analytical stage
enzymes- horseradish peroxidase, g6pd, alk phos
substrates- OPD, NADH to NAD
analysis of EIA results
must include controls in assay- 3 neg and 2 pos
- if absorbance is greater than or equal to cutoff of negative control= reactive
- if pos, repeat EIA and followup w/ conf test
- high sensitivity, some specificity
