JAAS News

Determination of Sr to study geological processes

The different isotopes of Strontium (Sr) can provide information on biological, hydrological and geological processes. Measurements of the radiogenic isotopic composition (87Sr/86Sr) have been used for a long time to study these processes, but in the last 30 years the stable isotopic ratio (88Sr/86Sr) has shown potential to help better understand the source of Sr and the cause of mass fractionation, especially when combined with 87Sr/86Sr measurements.

Leonid Neymark and scientists from both the US Geological Survey in Denver and the Instutute of Precambrian Geology and Geochronology of the Russian Academy of Sciences developed a thermal ionisation mass spectrometry (TIMS) method to measure Sr concentration, and “true” 88Sr/86Sr, 87Sr/86Sr and δ88Sr values. “True” values of isotopic ratios are considered those that are caused by natural fractionation, so the values measured have to be corrected for any chemical separation occurring during the measurement. This was achieved by spiking the samples with two Sr isotopes, in this study 87Sr-84Sr, with a precisely known ratio.
Standards, along with fossils, modern fauna, abiogenic minerals, silicate whole rocks and various water samples were analysed and the total range of values of δ88Sr shows potential for δ88Sr to be used as a tracer alongside the 87Sr/86Sr tracer.

To read the full article, please access the link below. This paper will be free to read until 6 january 2014.

Precise determination of δ88Sr in rocks, minerals, and waters by double-spike TIMS: a powerful tool in the study of geological, hydrological and biological processes
Leonid A. Neymark, Wayne R. Premo, Nikolay N. Mel’nikov and Poul Emsbo
J. Anal. At. Spectrom., 2014,29, 65-75
DOI: 10.1039/C3JA50310K

Determination of osmium in small biological samples

The high concentrations of osmium (Os) in sediments and the highly toxic nature of OsO₄(a gaseous osmium oxide) have been the main interest of a number of studies. Isotope abundance ratio measurements of  ¹⁸⁷Os/¹⁸⁸Os can provide valuable information about the source of Os, and concentration measurements can help define future toxicity effects. However, studies of biological samples are impeded by low accuracy and long measurement time of the available methods.

Nicola Pallavicini and colleagues at the Lulea University of Technology, Sweden, developed a methodology for the analysis of biological samples using double-focusing, sector field inductively coupled plasma mass spectrometry to measure the concentration of Os and also Os isotope ratio. The samples were prepared with microwave assisted acid digestion and spiked with Os of known isotope ratio. The method proved to be reproducible, relatively rapid and allowed high through-put of samples. The samples included different tissues from herbivore rodents and reference materials of biological and plant origin, allowing the method to provide information about Os metabolism and toxicity and also potential use of the Os isotope system in applications such as food authentication.

To read more about this article, please access the link below. This paper will be free to read October 18^th.

A high-throughput method for the determination of Os concentrations and isotope ratio measurements in small-size biological samples
Nicola Pallavicini, Frauke Ecke, Emma Engström, Douglas C. Baxter and   Ilia Rodushkin
J. Anal. At. Spectrom., 2013,28, 1591-1599
DOI: 10.1039/C3JA50201E

Isotope determination by portable laser ablation sampling

A portable laser ablation sampling device can help analyse valuable historical artifacts.

The study is shown in a paper just published in JAAS by Advisory Board member Detlef Günther and colleagues at the Swiss Federal Institute of Technology, ETH, Zürich, Switzerland.

The researchers used laser ablation coupled to a multicollector inductively coupled plasma mass spectrometry (LA-ICPMS) to determine lead isotopes in Chinese ceramics, and applied a portable device to enable remote analysis. Laser generated aerosol samples were collected on membrane filters and consequently analysed in the laboratory by LA-ICPMS. With the new device, sampling of objects is independent of their location, size and shape.

This new method showed an analytical performance similar to a laboratory-based analysis and enabled simultaneous isotopic and elemental analysis without invasive sampling such as scraping or drilling of the objects.

To know more about this study, please access the link below. This paper will be free to read until May 24^th.

Isotope ratio determination of objects in the field by portable laser ablation sampling and subsequent multicollector ICPMS
Reto Glaus, Ladina Dorta, Zhiguo Zhang, Qinglin Ma, Heinz Berke and   Detlef Günther
J. Anal. At. Spectrom., 2013, Advance Article
DOI: 10.1039/C3JA30379A