Determining pollution level of a medium without wasting tools, time or solvents possible

 Polycyclic aromatic hydrocarbons (PAH) are organic compounds that can be highly contaminant. They are found, amongst other places, in soils occupied by metallurgical or pharmaceutical industries and in waters polluted by ships' fuel. Chemist Dani Zuazagoitia has proposed simple techniques for analysing the impact of PAHs on a number of media, based on headspace solid phase microextraction (HS-SPME). He drew up the methodology, prepared it for the pertinent circumstances and applied it in the Basque province of Gipuzkoa.

Zuazagoitia defended the thesis at the University of the Basque Country(UPV/EHU), with the title Fase solidoko mikroerauzketan oinarritutako metodoen garapena hidrokarburo aromatiko poliziklikoen determinaziorako. Aplikazioa eta ebaluazioa ingurumen laginetan (Development of SPMEs for determining PAHs. Application and evaluation in environmental samples).

Zuazagoitia has published a number of articles on his research, the latest being in the journal Soil & Sediment Contamination, and entitled "Evaluation of soil contamination by polycyclic aromatic hydrocarbons in Gipuzkoa (Northern Spain)".

Extraction without touching the sample

The HS-SPME procedure for the analysis of samples is a screening method; these analyses provide a rapid response (positive/negative) without wasting tools, time or solvents. With this procedure in concrete, a needle is inserted into the sample container top. This needle contains a fibre that has to be taken out of it on insertion, so that the substance to be analysed is absorbed from the headspace. This space is that between the sample and the cap and information can be obtained from there only in the case of volatile compounds such as PAHs. The procedure of extraction from the headspace enables conserving the fibre in optimum conditions. If it is inserted directly into the sample it can be spoilt due to the large molecules, but using HS-SPME, non-volatile and large molecule interference is avoided.

After extraction desorption should be proceeded with, in order to free the gases absorbed by the fibre and thus separate the substances. Zuazagoitia opted for gas chromatography, by which the components can be separated with notable volatility at temperatures less than 350-400 degrees. Subsequently, the components were quantified using an FIDionisation detector.

Optimisation of three procedures

For his thesis Zuazagoitia developed methods which, based on HS-SPME, determined various small and medium molecular weight PAHs simultaneously, considering the diversity of conditions that these methods have to comply with, depending on the matrix to analyse (water, earth, sediments, and so on). Likewise, given the numerous variables that condition the process, an experimental design that optimised the response of the method was opted for. Using the Statistica® programme, it is not necessary to carry out trials with each variable in order to ascertain their ups and downs beforehand.

Zuazagoitia stated that, effectively, there exist rapid and simple methods and that can be undertaken with any laboratory analytical tools. Other characteristics of these methods involve having a rapid response (positive/negative) objective and being environmentally friendly, on not using organic solvents. The three procedures optimised in the thesis (water, earth, sediments) comply with these features.

In San Sebastián, Bergara and Pasaia

The researcher also took on the task of putting into practice methods for studying the pollution of water, earth and sediments in Gipuzkoa. According to the samples analysed, the concentrations of PAHs in the sea and river water in the territory are not relevant. However, there is a high level of contamination in leached waters, meaning that there is a high concentration of PAHs in soil these originate from. With the soil samples, Zuazagoitia detected high levels of pollution in two zones of San Sebastian (the capital city of Gipuzkoa): in an area where a gas factory used to be located (in Morlans, Amara); and in a store for timber that was treated with creosote, a toxic substance (in Oriamendi). Finally, as regards sediments, PAHs were found in all the locations analysed and especially in the towns of Bergara (river Deba) and Pasaia (river Oiartzun).

Story Source:

The above story is reprinted (with editorial adaptations ) from materials provided by Elhuyar Fundazioa.

Unearthing the appearance of ancient animals: X-ray technique for determining fossil pigmentation patterns

An international team including University of Pennsylvania paleontologists is unearthing the appearance of ancient animals by using the world's most powerful X-rays. New research shows how trace metals in fossils can be used to determine the pigmentation patterns of creatures dead for more than a hundred million years.

The research was conducted by an international team working with Phillip Manning, an adjunct professor in the School of Arts and Sciences' Department of Earth and Environmental Science, and Peter Dodson, a professor in both the Department of Earth and Environmental Science and the School of Veterinary Medicine's Department of Animal Biology. They collaborated with Roy Wogelius of the University of Manchester, Uwe Bergmann of Stanford University's SLAC National Accelerator Laboratory and other researchers.

Their work will be published in the journal Science on July 1.

Manning and Dodson have long studied fossils of the earliest birds, including Confuciusornis sanctus, which lived 120 million years ago and was one of many evolutionary links between dinosaurs and birds, and Gansus yumenensis, which is considered the oldest modern bird and lived more than 100 million years ago. Their partnership with researchers from Manchester and Stanford, however, has opened a new avenue of investigation.

"Every once in a while we are lucky enough to discover something new, something that nobody has ever seen before," said Wogelius, a geochemist and the paper's lead author.

The team's discovery is rooted in a new technique, using technology based on synchrotron radiation to identify copper-bearing molecules in the fossilized feathers of these ancient birds.

"There is an intimate relationship between trace metals and organics. When you're getting a good suntan, melanin forms in your skin. There are many forms of melanin, and some are found in the dark feathers of birds, but copper is always bound into its structure," Manning said. "You can see this in living animals, but it's only since we've been using a synchrotron -- a vast accelerator that generates intense X-rays a hundred million times brighter than the sun -- that we can see the chemical detail in fossils and show that the copper complexes we found were originally part of the animal."

Metallic compounds can survive in these fossils for hundreds of millions of years because they are unpalatable to microorganisms. But to distinguish the copper that was bound in melanin with copper that might have been geochemically produced requires the precision that only a tool like the synchrotron can provide. By measuring the energy released by atoms when they are bombarded with high-powered X-rays, researchers can get an accurate picture of the molecules in which they reside.

"We're able to map absolute quantities, to parts-per-million levels in discrete biological structures, which we compare with living organisms and see they are comparable," Manning said.

The new technique paints a richer picture of the lives of these ancient creatures.

"While our work doesn't yet allow you to diagnose color, you can get the concentration and distribution of pigments," Dodson said. "In other words, you can work out monochrome patterns, which may tell us something about camouflage or other traits relevant to natural selection of the species."

"If we could eventually give colors to long extinct species, that in itself would be fantastic," said co-author Uwe Bergmann, deputy director of the Linac Coherent Lightsource at SLAC. "But synchrotron radiation has revolutionized science in many fields, most notably in molecular biology. It is very exciting to see that it is now starting to have an impact in paleontology, in a way that may have important implications in many other disciplines,"

The team is confident that further research with this technique will enable them to fully diagnose color via fossil chemistry, and they also believe that this is only one of many applications the technique will have.

"This synchrotron research is really important as it gives us the first clue to really understanding what happens with organic debris when you bury it in the ground," Manning said. "For example, there are huge implications for understanding the mass transfer of buried waste; trace metals can be bad if you get too much of them, so we can spatially map and give images of exact loadings of these metals in both living and extinct organisms. No one else can do this. It's not just contributing to a field, it's creating a whole new discipline."

In addition to Wogelius, Manning, Dodson and Bergmann, the research was conducted by Holly Barden, Nick Edwards and William Sellers, of Manchester University; Peter Larson of Manchester University and the Black Hills Institute of Geological Researc, Inc.; Kevin Taylor of Manchester Metropolitan University; Sam Webb of the SLAC National Accelerator Laboratory; Hai-lu You of the Chinese Academy of Geological Sciences; and Li Da-qing of the Gansu Geological Museum.

Support for this research was provided by the United Kingdom's National Environmental Research Council and an anonymous private donor.

Fossil samples were provided by the Black Hills Institute Museum and the Museum für Naturkunde, Humboldt University, Berlin. The Stanford Synchrotron Radiation Lightsource at SLAC is a Department of Energy Office of Science national user facility which provides synchrotron radiation for research in chemistry, biology, physics and materials science to more than a thousand users each year.

Story Source:

The above story is reprinted (with editorial adaptations ) from materials provided by University of Pennsylvania.

Journal Reference:

R. A. Wogelius, P. L. Manning, H. E. Barden, N. P. Edwards, S. M. Webb, W. I. Sellers, K. G. Taylor, P. L. Larson, P. Dodson, H. You, L. Da-Qing, U. Bergmann. Trace Metals as Biomarkers for Eumelanin Pigment in the Fossil Record. Science, 2011; DOI: 10.1126/science.1205748