Availability◦ Synthetic◦ Natural – Produced From Animals◦ Monoclonal Antibodies

Purity – Competing Reactions with Impurities

Stability – Store in Albumin Serum Specificity – Binding Constant

Must Have Similar Binding Properties as Unlabeled Ligand

Internally Labeled Ligand ◦ 14C and 3H

Externally Labeled Ligand ◦ 131I and 125I

By-Products or Incomplete Synthesis◦ Purification by chromatography (gel filtration)

Electrophoresis Gel Filtration Adsorption Chromatography Fractional Precipitation

◦ Centrifugation◦ Filtration

Partition Chromatography◦ Dialysis

Enzymeimmunoassays (EIA) ◦ millimolar

Fluoroimmunoassays (EIA) ◦ micromolar

Radioimmunoassays (EIA) ◦ nanomolar to picomolar

Endocrinology◦ Insulin, HCG, Vasopressin◦ Detects Endocrine Disorders◦ Physiology of Endocrine Function

Pharmacology◦ Morphine◦ Detect Drug Abuse or Drug Poisoning◦ Study Drug Kinetics

Epidemiology◦ Hepatitis B

Clinical Immunology◦ Antibodies for Inhalant Allergens◦ Allergy Diagnosis

Oncology◦ Carcinoembryonic Antigen◦ Early Cancer Detection and Diagnosis

Based on Simple Biochemistry Principles Establish Ideal Binder and Ligand Synthesize Tracer Ligand Separation of Bound and Free Parts High Precision and Sensitivity Powerful Applications to a Wide Range of

Medical Fields