title: A micro-scale method for liquid scintillation counting, applicable to radioimmunoassay of steroids and substances of comparable relative molecular mass.
abstract: A major expense of radioimmunoassay involving tritiated tracers is that of liquid scintillation counting. We present a micro-scale method that markedly reduces the cost of liquid scintillation counting. The radioimmunoassay is done in 10 X 50 mm tubes. The antibody-bound tracer is precipitated with a second antibody, the precipitate is resuspended in 0.1 ml of water, and 0.3 ml of dioxane is added. One milliliter of a toluene-based scintillation cocktail is added, and the tube is capped and placed in an adapter for liquid scintilation counting. When this method was applied to a double-antibody testosterone radioimmunoassay, it performed comparably to assays counted by the usual method.
mesh_terms: D003365:Costs and Cost Analysis; D008832:Microchemistry; D011863:Radioimmunoassay / Q000379:methods*; D012588:Scintillation Counting / Q000191:economics; D013256:Steroids / Q000032:analysis*; D013739:Testosterone / Q000032:analysis; D014316:Tritium
chemical_list: D013256:Steroids; D014316:Tritium; D013739:Testosterone