Modification of a commercially available digoxin radioimmunoassay kit for higher precision

The procedure prescribed for the Schwarz/Mann 125-l-digoxin kit was modified with regard to pipetting and counting procedure. Incubation time with dextran-coated charcoal was also investigated. The modifications resulted in a significantly higher precision wihout introduction of a systematic error and the analysis time per eight-tube batch was decreased by 20 min.