Eliminating molybdenum oxide interference in urine cadmium biomonitoring using ICP-DRC-MS

A new method for urine cadmium biomonitoring is presented. It uses inductively coupled plasma dynamic reaction cell mass spectrometry (ICP-DRC-MS) to eliminate molybdenum-based polyatomic interferences. The method began to be used in the National Health and Nutrition Examination Survey (NHANES) starting with the 2003-2004 survey cycle. Removal of moybdenum-based polyatomic interferences was found to reduce observed urine cadmium concentrations by a signficant amount, 37% at the 50(th) percentiles, for a subset (N = 2066) of NHANES 2003-2004 urine specimens. To avoid creating an artificial shift in NHANES data with the introduction of this method, urine cadmium results for survey cycles 1999-2000 and 2001-2002 were republished (www.cdc.gov/exposurereport/report.htm,(1) www.cdc.gov/nchs/datawh.htm(2)) after mathematical adjustment correcting for the bias on the basis of their previously determined molybdenum concentrations. Data supporting this mathematical adjustment are presented in this article. Blood cadmium data presented here show that at the normal levels of blood molybdenum, no significant molybdenum-based interferences are observed.