Radioimmunoassay (RIA)
RIA involves the separation of the drug using the specificity of antibody - antigen binding and quantitation using radioactivity.
Components of RIA Assay Kit
- Drug
- Antibody
- Labelled Drug
General Procedure for Performing a RIA Analysis
- Mix sample containing drug with fixed quantity of labelled drug and antibody
- Allow to equilibrate - incubate
- Separate drug bound to antibody from unbound drug
- Charcoal adsorption of antibody (and bound drug)
- Antibody - antibody binding precipitates bound drug
- Antibody bonded to container
- Measure radioactivity associated with bound labelled drug
- low drug concentration means more bound radioactivity and higher measurement
- high drug concentration means less bound radioactivity and lower measurement
- Determine standard curve
- Non-linear plot of radioactivity versus concentration
- Logit-log concentration plot is linear
A Blank and Three Standard Samples
Fig 3.7.1 RIA before and after Incubation - Blank and Three Standard Samples
Table 3.7.1 Bound and Free Drug Concentrations
| Total [Drug] | Bound [Drug] | Free [Drug] |
| 0 | 6 | 0 |
| 3 | 4 | 2 |
| 6 | 3 | 3 |
| 12 | 2 | 4 |
Fig 3.7.2 Plot of Bound versus Total Drug Concentration
Fig 3.7.3 Logit versus Log Total C Plot
References
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Copyright 2001-3 David W. A. Bourne (david@boomer.org)
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Sunday 26 Jan 2003 at 08:48 PM