title: Quantitation of lead-210 (210Pb) using lead-203 (203Pb) as a "Massless" yield tracer.
abstract: Determination of Pb-210 (210Pb) in aqueous solution is a common radioanalytical challenge in environmental science. Widely used methods for undertaking these analyses (e.g., ASTM D7535) rely on the use of stable lead (Pb) as a yield tracer that takes into account losses of210Pb that inevitably occur during elemental/radiochemical separations of the procedures. Although effective, these methods introduce technical challenges that can be difficult to track and potentially introduce uncertainty that can be difficult to quantify. Examples of these challenges include interference from endogenous stable Pb in complex sample matrices; contamination of stable Pb carrier with210Pb; and high detection limits due to counting efficiency limitations. We hypothesized that many of these challenges could be avoided by the use of the electron-capture, gamma-emitting isotope,203Pb as a chemical yield tracer in the analysis of210Pb. A series of experiments were performed to evaluate the efficacy of203Pb as a tracer. Four different matrices were analyzed, including a complex matrix (hydraulic-fracturing produced fluids); and samples comprising less complicated matrices (i.e., river water, deionized water, and tap water). Separation techniques and counting methodologies were also compared and optimized. Due to a relatively short-half life (52 h),203Pb tracer is effectively massless for the purposes of chemical separations, allowing for reduced chromatography column resin bed volumes. Because203Pb is a gamma emitter (279 keV; 81% intensity), recovery can be determined non-destructively in a variety of matrices, including liquid scintillation cocktail. The use of liquid scintillation as a counting methodology allowed for determination of210Pb activities via210Pb or210Po; and recoveries of greater than 90% are routinely achievable using this approach. The improved method for the analysis of210Pb in aqueous matrices allows for the analysis of complex matrices, at reduced cost, while providing greater counting flexibility in achieving acceptable detections limits.
authors.affiliation: State Hygienic Laboratory at the University of Iowa, Coralville, IA 52241, United States; Interdisciplinary Human Toxicology Program, University of Iowa, Iowa City, IA 52242, United States. Electronic address: dustin-may@uiowa.edu.
authors.forename: D
authors.initials: D
authors.lastname: May
authors.affiliation: Interdisciplinary Human Toxicology Program, University of Iowa, Iowa City, IA 52242, United States; Department of Chemistry, University of Iowa, Iowa City, IA 52242, United States. Electronic address: awnelso@sandia.gov.
authors.forename: A N
authors.initials: AN
authors.lastname: Nelson
authors.affiliation: Interdisciplinary Human Toxicology Program, University of Iowa, Iowa City, IA 52242, United States; Department of Chemistry, University of Iowa, Iowa City, IA 52242, United States; Departments of Radiology and Radiation Oncology, Free Radical and Radiation Biology Program, University of Iowa, Iowa City, IA 52242, United States. Electronic address: michael-schultz@uiowa.edu.
authors.forename: M K
authors.initials: MK
authors.lastname: Schultz
mesh_terms: D007856:Lead Radioisotopes / Q000032:analysis*; D057230:Limit of Detection; D011834:Radiation Monitoring / Q000379:methods*; D015203:Reproducibility of Results; D012588:Scintillation Counting
chemical_list: D007856:Lead Radioisotopes
keywords: Lead-203; Lead-210; Polonium-210