A. Retzmann, T. Zimmermann, D. Pröfrock, T. Prohaska, J. Irrgeher (2017): A fully automated simultaneous single-stage separation of Sr, Pb, and Nd using DGA Resin for the isotopic analysis of marine sediments. Analytical and Bioanalytical Chemistry, pp 1–18, doi: 10.1007/s00216-017-0468-6
A novel, fast and reliable sample preparation procedure for the simultaneous separation of Sr, Pb, and Nd has been developed for subsequent isotope ratio analysis of sediment digests. The method applying a fully automated, low-pressure chromatographic system separates all three analytes in a single-stage extraction step using self-packed columns filled with DGA Resin. The fully automated set-up allows the unattended processing of three isotopic systems from one sediment digest every 2 h, offering high sample throughput of up to 12 samples per day and reducing substantially laboratory manpower as compared to conventional manual methods. The developed separation method was validated using the marine sediment GBW-07313 as matrix-matched certified reference material and combines quantitative recoveries (>90% for Sr, >93% for Pb, and >91% for Nd) with low procedural blank levels following the sample separation (0.07 μg L−1 Sr, 0.03 μg L−1 Pb, and 0.57 μg L−1 Nd). The average δ values for Sr, Pb, and Nd of the separated reference standards were within the certified ranges (δ (87Sr/86Sr)NIST SRM 987 of −0.05(28) ‰, δ(208Pb/206Pb)NIST SRM 981 of −0.21(14) ‰, and δ(143Nd/144Nd)JNdi-1 of 0.00(7) ‰). The DGA Resin proved to be reusable for the separation of >10 sediment digests with no significant carry-over or memory effects, as well as no significant on-column fractionation of Sr, Pb, and Nd isotope ratios. Additional spike experiments of NIST SRM 987 with Pb, NIST SRM 981 with Sr, and JNdi-1 with Ce revealed no significant impact on the measured isotopic ratios, caused by potential small analyte peak overlaps during the separation of Sr and Pb, as well as Ce and Nd.
Vetere, A., Pröfrock, D. and Schrader, W. (2017): Quantitative and qualitative analysis of three classes of sulfur compounds in crude oil. Angew. Chem. Int. Ed., doi:10.1002/anie.201703205
Due to environmental hazards arising from sulfur containing combustion products, strong legal regulations exist to reduce the sulfur content of transportation fuels down to a few ppm. With the ongoing depletion of low-sulfur crude oil reservoirs, increased technological efforts are needed for crude oil refining to meet these requirements. The desulfurization step is a critical part of the refining process but partly suffers from recalcitrance of certain species against sulfur removal and the inability to quantitatively understand the behaviour of individual classes during the process. Here a new and simple approach for the parallel quantification of three different classes of sulfur species present in crude oils using LC-separation and an online detection and quantification by ICP-MS is shown. This new and simple approach will help to estimate the amount of recalcitrant species and thus to allow a better optimization of desulfurization conditions during fuel production.