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When Is Clean, Clean Enough?

Jane Rothert and Christopher Lehmann
Central Analytical Laboratory, Illinois State Water Survey
2204 Griffith Dr., Champaign, IL 61820


The Central Analytical Laboratory (CAL) for the National Atmospheric Deposition Program (NADP) has been providing clean sampling supplies for almost 30 years to the Atmospheric Integrated Research Monitoring Network (AIRMoN) and the National Trends Network (NTN). During this period, method detection limits have changed considerably, dropping by an order of magnitude for many analytes. Traditionally, sampling supplies were thought to be clean when laboratory blank analyte concentrations were below detectable levels. However this is no longer true, and may never have been fully true. The very low detection limits achieved in recent years with the CAL’s newest generation of instruments allow the quantification of contamination in virtually all supplies provided to the NTN and AIRMoN. This poster will look at supply cleanliness for the past 11 years to see if supplies are getting dirtier or if the current lower detection limits simply make it possible to see contamination that wasn’t visible in the past.