Elemental and Isotopic Analysis

This paper aims to discuss the origin and significance of the so-called spoked-wheel amulets from the late Iron Age (3rd to 1st century BC). The type with eight spokes, which most resembles a real chariot wheel, was discovered to be made of a specific alloy containing a large amount of lead and a significant amount of antimony, plus traces of silver and arsenic. This combination of elements signifies the use of a copper known as fahlore (tetrahedrite). Its use in Bohemia after the early Bronze Age is rarely observed, if at all. These amulets are therefore a conspicuous exception. Research in Bavaria has revealed other objects made from fahlore copper. Another connection to Bavaria may be indicated by coin hoards accompanied by bronze closure rings of a similar alloy design. Other cases may suggest that antimony was added as a separate component. Here we discuss the composition and provenance of these objects from the perspective of compositional and lead isotope analysis.

Loss-on-ignition (LOI) is widely used to estimate organic carbon (OC) content, and thus carbon stocks, due to easy operation and low costs. The wide use of a conversion factor of 1.724 (LOI:OC) oversimplifies the relationship between LOI and OC, and may lead to significant biases in estimating global sediment carbon stocks in 'blue carbon' ecosystems. We estimated sediment OC using LOI at different mangrove and saltmarsh sites in Hong Kong. OC of matched samples from the same sites was independently measured using an elemental analyzer. The sites are mostly typical mineral sediments with LOI less than 8%. The conversion factors of LOI:OC are 5.376 and 4.673 for mangroves and saltmarshes, respectively. This means the use of the common conversion factor will overestimate mangrove and saltmarsh sediment carbon stocks by 212% and 171%, respectively, in our studied sites. We also found that LOI can be used to estimate leaf and root OC (organic nitrogen) by conversion factors of 2.978 (12.837) and 1.737 (27.027), respectively. Our results highlight the urgency to correct the bias in estimating OC and carbon stocks from LOI in 'blue carbon' ecosystems, and the potential of using LOI for estimating leaf and root OC and organic nitrogen. The difference in the conversion factors between mangroves and saltmarshes, and between mineral and organic sediments should be taken into account when estimating OC from LOI for these wetlands.

Samples of coal were collected from different seams at a South African coal mine and comparative leaching experiments were carried out under various pH conditions and times to investigate the leaching behavior and potential environmental impact of possibly hazardous elements such as As, Cd, Co, Cr, Mn, Ni, Pb, Th and U. The calculated leaching intensities, sequential extraction results and cumulative percentages demonstrate that the leaching behavior of the elements is strongly influenced by the pH, the leaching time and the properties and occurrences of the elements. The leached concentrations of As, Cd, Co, Cr, Mn, Ni and Pb exceeded the maximum concentrations recommended by the Environmental Protection Agency (EPA) for surface water.

The Upper Cretaceous succession in the Big Bend Region of West Texas is plagued by the continued use of provincial lithostratigraphic terms not used elsewhere in the state of Texas. These provincial terms greatly limit: (1) correlating these strata to coeval units in outcrops, as well as the subsurface, elsewhere in Texas; and (2) utilizing these outcrops as windows to examine strata coeval to economically important unconventional reservoirs within the Eagle Ford Group in the subsurface of South Texas. However, with the use of petrophysical and geochemical techniques (handheld spectrometer, X–ray fluorescence [XRF], and stable isotopes), it is possible to identify and define the Eagle Ford and Austin groups, as well as potentially a remnant of the older Woodbine Group, within Big Bend National Park, Brewster County, Texas. Because the Hot Springs section is west of the classic Eagle Ford and Austin outcrops in the Lozier Canyon region of Terrell County (West Texas), the Big Bend outcrops also provide insights into lateral facies changes within these units. As historically defined, within the Big Bend region, the Boquillas Formation overlies the Buda Formation and is overlain by the Pen Formation. Futhermore, the Boquillas Formation is divided into a lower Ernst Member and an upper San Vincente Member, while the Ernst Member is divided into four informal sub-members referred to as units 1 to 4 from the base upwards. Correlations from Lozier Canyon revealed that the Boquillas Formation at Hot Springs is equivalent to both the Eagle Ford and Austin groups in the Lozier Canyon region of West Texas. The Eagle Ford Group defined in Lozier Canyon is equivalent to units 1 to 3 of the Ernst Member at Hot Springs. Our work also suggests that unit 1 of the Ernst Member at Hot Springs is equivalent to the Lower Eagle Ford in Lozier Canyon, while units 2 and 3 of the Ernst Member at Hot Springs is equivalent to the Upper Eagle Ford at Lozier Canyon. 161

Anecdotal evidence as well as observations made in our own stable isotope laboratory suggest for samples with either a high alkali and/or halogen content (such as marine samples or certain soil samples) or a high carbon and oxygen content (such as carbohydrates) to result in flash combustion temperatures exceeding temperature or burn time or both of flash combustion under typical conditions.  Whatever the exact circumstances during combustion of such samples, they compromise chemical and thus structural integrity and thus weaken the wall of the quartz glass reactors in the combustion zone and ultimately lead to pin-prick holes being formed through which carrier gas escapes thus resulting in a dramatic loss of carrier gas flow.  Occasionally these pin-prick holes get plugged or “sealed” by molten tin thus restoring carrier gas flow but at the other end of the spectrum these pin-prick holes can become so wide for molten tin being able to pass through and to run down the outside of the reactor tube.  In the latter event, a catastrophic failure of the reactor tube is inevitable with carrier gas flow downstream of the holes dropping to almost zero.
While pin-prick holes (going unnoticed during an autosampler run of a large batch of samples) typically result in the loss of 3 or 4 samples until the hole/s “self-sealed” with molten tin, in a worst case scenario a catastrophic failure of the reactor tube can result in the loss of 40 or more samples (depending on number of samples in a batch run and when the failure occurred).
Here we present examples of combustion reactor failure as well as observations made with crucibles made of quartz glass, stainless steel or inconel alloy during experiments to see if crucible design can mitigate against the effects of problematic samples.
Geophysical Research Abstracts, 15, EGU2013-13881.

The quantification of active ingredients (AI) in drugs is a crucial and important step in the drug quality control process. This is usually performed by using wet chemical techniques like LC-MS, UV spectrophotometry and other appropriate organic analytical methods. However, if the active ingredient contains specific heteroatoms (F, S, Cl…), elemental IBA like PIXE and PIGE techniques, using small tandem accelerator of 1-2 MV, can be explored for molecular quantification. IBA techniques permit the analysis of the sample under solid form, without any laborious sample preparations. In this work, we demonstrate the ability of the Thick Target PIXE technique for rapid and accurate quantification of both low and high concentrations of active ingredients in different commercial drugs. Fenofibrate, a chlorinated active ingredient, is present in high amounts in two different commercial drugs, its quantification was done using the relative approach to an external standard. On the other hand, Tiemonium methylsulfate which exists in relatively low amount in commercial drugs, its quantification was done using GUPIX simulation code (absolute quantification) The experimental aspects related to the quantification validity (use of external standards, absolute quantification, matrix effect,...) are presented and discussed.