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  • 1 University of London Isotope Unit, Queen Elizabeth College Campden Hill W8 7AH London (England)
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A method for quench correction of samples with double radioactive labelling is described. Each nuclide makes a contribution to the counting rate of three channels of a liquid scintillation counter. This channel overlap is an essential requirement of the calibration procedure rather than a limitation, and allows more freedom in the choice of counting conditions. After calibration with suitable standards the method will tolerate wide variations in the ratio of one isotope to the other extending to single label samples of either isotope. This is the outstanding advantage over the channel ratio method which requires a statistically significant counting rate for the higher energy isotope. The method takes advantage of the facilities offered by a computer which may be on line or remote.14C and tritium are used to demonstrate the utility of the method.