Dual isotope separation technique for radioassay. The effect of cross counting between two simultaneously counted...

A theoretical model, describing the effects of cross counting on the dual-isotope-corrected bound count rate and on the precision with which it is estimated, is presented. Experimental support for the validity of the model is given. The bound count rate is shown to be independent of the amount of marker isotope incorrectly counted as label isotope. The precision with which the bound count rate is estimated appears to be dependent on the size of this cross counting correction, although other factors such as pipetting errors are of more importance. Implications for the choice of assay system are discussed.