1. A method of identifying a radionuclide in a test sample comprising same, said method comprising: (a) establishing at least one linear equation for a relationship among liquid scintillation spectral characteristics for each of a series of radionuclides which might be present in the test sample; (b) determining characteristic ranges of values of the liquid scintillation spectral characteristics for each of the series of radionuclides; (c) measuring the spectral characteristics employed in said at least one linear equation for the test sample; and (d) comparing the measured spectral characteristics for the test sample against the determined characteristic values.