Radioisotopic Labels
•Types of radiation:
•beta ($)
•gamma (()
•Half-life:
•Definition:
•the time during which half of a substance will be converted to a product or eliminated by a process.
•in the case of radioactive half-life it is when half of the radioisotope has decayed (one nuclide transforms into another nuclide by emission of particles)
•Examples:
•42K
•131I
•125I
•57Co
•3H
•14C
•12.4 hours
•8.1 days
•60 days
•270 days
•12.26 years
•5,730 years
•3H (tritium), 42K (potassium), 131I (iodine), 14C (carbon)
•57Co (cobalt), 125I (iodine)
•125I (iodine) emits very low energy photons - scintillation detector