Knowledge Base

Goal: Multi-element isotope ratio analysis is becoming increasingly important, particularly in food authenticity control and forensic applications. With the introduction of the Thermo Scientific ConFlo IV universal interface in July 2007, the ability for multi-element isotope ratio determination was both enhanced and simplified.

Goal: Honey is subject to fraud by adulteration with low price invert sugar syrups. Saccharides in syrups derived from cane, corn or beet sugar are difficult to distinguish from those in pure honeys. AdulterationSugar cane and corn syrups, the most widely used adulterants, have distinctive isotopic 13C signatures because both sugar cane and corn plants use the C4 photosynthetic pathway in contrast to most honey which is derived from plants that use the C3 photosynthetic pathway. These differences in 13C isotopic composition allow detection of > 7% addition of such sugars.

Goal: Isotopic analysis of small (6-130 μg) samples of CaCO3 is increasingly important in paleoclimatic reconstructions. The requirement for isotopic analysis of small samples of carbonate arose in studies of biogenic carbonates (e.g. foraminifera, bivalves, brachiopods, otoliths, corals).

Goal: Isotopic analyses of foods have become a widespread tool to evaluate the quality, authenticity and origin of labeled products. According to the standard procedure, wines, alcoholic beverages and fermented fruit juices are distilled to gain ethanol. Ethanol can be analyzed for oxygen and carbon isotope composition by elemental analyzers coupled to isotope ratio MS. The analyses allow the quantification of exogenous sugar added during the fermentation to increase the alcohol grade of the wine. The control of spirit drinks is needed also for the detection of frauds, such as mislabeling regarding both ingredients and origin.

Goal: Natural gas is produced by biodegradation and by thermal degradation of organic matter. The isotope ratios of compounds in natural gas can hold information about the substrate and the degradation processes. The 13C/12C isotope ratios of all components in natural gas, including methane, can be analyzed within the same GC-IRMS run.

Goal: The isotope ratio analysis of hydrocarbons and their precursors (e.g. porphyrins) in ancient depositional environments provides insight into specific conditions of diagenesis. Such kinds of samples typically are very complex mixtures (e.g. crude oil), requiring highly efficient separation and background correction prior to isotope ratio measurement.

Goal: The analysis of amino acids is an important topic in medical and biological studies. GC-IRMS is a powerful technique for the investigation of metabolic pathways either by conducting tracer experiments or by studying the natural abundance of 15N or 13C in amino acids.

Goal: Isotope ratio monitoring-LC/MS (irm-LC/MS) with the Thermo Scientific LC IsoLink helps to determine the sources of pharmaceuticals via the individual 13C/12C ratio (δ13C values) of the ingredients. Small amounts in complex mixtures can be applied for compound specific isotope analysis without extensive preparation or derivatization.

Goal: The application of straw and biochar to soil has received great attention because of their potential benefits such as fertility improvement and carbon (C) sequestration. The abiotic effects of these materials on C and nitrogen (N) cycling in the soil ecosystem have been previously investigated, however, the effects of straw or its derived biochar on the soil microbial community structure and function are not well understood. For this purpose, a short-term incubation experiment was conducted using 13C-labeled rice straw and its derived biochar (13C-labeled biochar) to deepen our understanding about soil microbial community dynamics and function in C sequestration and greenhouse gas emission in the acidic paddy soil amended with these materials.

Goal: Saltpetre (KNO3) is the major ingredient of gunpowder, which played a driving force in political changes during the late medieval to middle modern times in the world. The intrinsic isotopic parameters of the mineral are useful for elucidating the origin and following its marketing route. Dual isotopic analysis (oxygen together with nitrogen, as expressed by δ18O and δ15N notations, respectively) was made for nitrates from diverse gunpowder samples which prevailed during the 19th century in Japan. Three distinctive sources which represent Japanese domestic (characterized by low δ18O–low δ15N values), British Indian (characterized by clearly higher δ18O–higher δ15N values) and Atacama Desert nitrates (characterized by very high δ18O up to + 50‰ - δ15N = around 0‰) were determined by binary plotting. Some samples recovered from portable powder reservoirs for less developed guns tend to exhibit a small shift in δ15N value toward a British Indian origin,

Goal: Mollusk shells excavated from archeological sites have been used to reconstruct paleoenvironment, human foraging, and migratory patterns. To retrieve information on past environment or human behavior, chemical signatures such as oxygen stable isotopes (δ18Oshell) are analyzed. Shell archeological remains usually represent food waste. Thermal treatments such as boiling and roasting may influence shell structure and biochemical composition. However, little is known about the relationship between changes at macro-, microstructural and chemical levels. This work is a calibration study on modern Phorcus (Osilinus) turbinatus shells. A simulation of two different cooking methods (boiling and roasting) was carried out at four temperatures (100 °C, 300 °C, 500 °C and 700 °C) for two durations (20 min and 60 min).

Goal: Measurements of δ2H and δ18O composition of pore waters in saturated and unsaturated soil samples are routinely performed in hydrological studies. A variety of in-situ and lab-based pore water extraction methods for the analysis of the stable isotopes of water now exist. While some have been used for decades (e.g. cryogenic vacuum extraction) others are relatively new, such as direct vapor equilibration or the microwave extraction technique. Despite their broad range of application, a formal and comprehensive intercomparison of soil water extraction methods for stable isotope analysis is lacking and long overdue. Here we present an intercomparison among five commonly used lab-based pore water extraction techniques (high pressure mechanical squeezing, centrifugation, direct vapor equilibration, microwave extraction, and cryogenic extraction).

Goal: Lakes undergoing major changes in phytoplankton species composition are likely to undergo changes in carbon (C) cycling. In this study we used stable C isotopes to understand how the C cycle of Lake Kinneret, Israel, responded to documented changes in phytoplankton species composition. We compared the annual δ13C cycle of particulate organic matter from surface water (POMsurf) between (1) years in which a massive spring bloom of the dinoflagellate Peridinium gatunense occurred (“Peridinium years”) and (2) years in which it did not (“non-Peridinium years”). In non-Peridinium years, the spring δ13C–POMsurf maxima were lower by 3.3‰. These spring δ13C maxima were even lower in POM sinking into sediment traps and in zooplankton (lower by 6.8 and 6.9‰, respectively). These differences in the isotopic composition of the major organic C components in the lake represent ecosystem-level responses to the presence or absence of the key blooming species P. gatunense .

Goal: A giant carbonate vein (≥ 50 m thick; fissure ridge travertines) and nearby travertine plateaus in the Semproniano area (Mt. Amiata geothermal field, southern Tuscany, Italy) are investigated through a multidisciplinary approach, including field and laboratory geochemical analyses (U/Th geochronology, C, Nd, O and Sr isotope systematics, REE abundances, and fluid inclusion microthermometry). The main aim of this work is to understand: (1) modes and rates for the growth of the giant vein and nearby travertine deposits within a Quaternary volcano-tectonic domain; (2) implications in terms of the CO2 leakage; and (3) possible relationships with Quaternary paleoclimate and hydrological oscillations. Results show that the giant vein was the inner portion of a large fissure ridge travertine and grew asymmetrically and ataxially through repeated shallow fluid injections between > 650 and 85 ka, with growth rates in th