Particle-enhanced turbidimetric inhibition immunoassay (PETINIA) is a homogeneous competitive immunoassay.
Antibody fragments and drug-latex particles will bind to form aggregates that increase the turbidity of the solution. Free drug from the sample competes for the antibody fragment, thereby decreasing the rate of particle aggregation.
The rate of aggregation is inversely proportional to the concentration of drug in the sample.
