Occasional discordant results on testing samples by radioimmunoassay for hepatitis B surface antigen and antibody led to this analysis of gamma counters used by different hospitals and testing laboratories. Eight dilutions of purified 125I were sent under code to 11 institutions doing radioimmunoassay testing. Results demonstrated a wide range in background counts-per-minute (cpm) as well as considerable variation between gamma counters in per cent counting efficiency for 125I (ranging from 20 to 48%). These data support the need for regular monitoring and calibration of gamma counters to ensure low background cpm as well as maximum counting efficiency. This will give reproducible and reliable results in radioimmunoassay testing.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.