Selective Diffusive Gradients in Thin Films (DGT) for the Simultaneous Assessment of Labile Sr and Pb Concentrations and Isotope Ratios in Soils

Stefan Wagner, Jakob Santner, Johanna Irrgeher, Markus Puschenreiter, Steffen Happel, Thomas Prohaska

Publikation: Beitrag in FachzeitschriftArtikelForschungBegutachtung


A method using diffusive gradients in thin films (DGT) for the accurate quantification of trace-level (μg L-1) Sr and Pb concentrations and isotope ratios [δSRM 987(87Sr/86Sr) and δSRM 981(207Pb/206Pb)] in labile, bioavailable element fractions in soils is reported. The method is based on a novel poly(tetrafluoroethylene) (PTFE) membrane binding layer with combined di(2-ethyl-hexyl)phosphoric acid (HDEHP) and 4,4′(5′)-bis-t-butylcyclohexano-18-crown-6 (crown-ether) functionality with high selectivity for Sr and Pb (TK100 membrane). Laboratory evaluation of the TK100 DGT showed linear uptake of Sr over time (2-24 h) up to very high Sr mass loadings on TK100 membranes (288 μg cm-2) and effective performance in the range of pH (3.9-8.2), ionic strength (0.001-0.1 mol L-1), and cation competition (50-160 mg L-1 Ca in a synthetic soil solution matrix) of environmental interest. Selective three-step elution of TK100 membranes using hydrochloric acid allowed us to obtain purified Sr and Pb fractions with adequate (≥75%) recovery and quantitative (≥96%) matrix reduction. Neither DGT-based sampling itself nor selective elution or mass loading effects caused significant isotopic fractionation. Application of TK100 DGT in natural soils and comparison with conventional approaches of bioavailability assessment demonstrated the method's unique capability to obtain information on Sr and Pb resupply dynamics and isotopic variations with low combined uncertainty within a single sampling step.

Seiten (von - bis)6338-6346
FachzeitschriftAnalytical chemistry
PublikationsstatusVeröffentlicht - 15 Apr. 2022

Bibliographische Notiz

Funding Information:
This study was funded by the Austrian Science Fund (FWF, P30085-N28). The authors also acknowledge funding provided to J.S. by FWF and the Federal State of Lower Austria (P27571-BBL). The authors thank Dipl.-Ing. Christina Hummel (University of Natural Resources and Life Sciences, Vienna), Prof. Domen Leštan (University of Ljubljana), and Dr. Dipl.-Ing. Wolfgang Friesl-Hanl (University of Natural Resources and Life Sciences, Vienna) for providing the soil materials. Laboratory assistance by Sarah Mühlbacher and Sara Widhalm is greatly appreciated.

Publisher Copyright:
© 2022 The Authors. Published by American Chemical Society.

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