Conference Agenda

Tree rings provide annual records of environmental and climatic conditions. These records can be interpreted through the physical characteristics of tree rings or the isotopic composition of their structural elements. Oxygen isotope chronologies are created by combining data from overlapping-aged trees, reflecting tree-environment interactions in the δ¹⁸O of tree-ring cellulose. The abundance of ¹⁸O in tree-ring cellulose is closely linked to hydroclimate, influenced by source water δ¹⁸O and atmospheric humidity. Long sequences of annually resolved tree-ring δ¹⁸O measurements have been used, to good effect, in the dating of archaeological timbers and as proxies in the reconstruction of climatic variables. In this research we have established a working methodology for producing and measuring δ¹⁸O in tree-ring α-cellulose at the Centre for Isotope Research. We have demonstrated an average precision of roughly 0.2‰ standard deviation under a variety of conditions, which exceeds the expected performance of continuous flow IRMS techniques. Difficulties were encountered during the correction of tree-ring cellulose δ¹⁸O measurements using non-cellulose, organic reference materials. Measurements of cellulose standards alongside water reference materials and an independent quality control standard proved successful, resulting in a number of cellulose standards being accurately placed on the VSMOW-SLAP scale, including the intercomparison and de facto reference material IAEA-C3 holocellulose.

Archaeologists often seek cause-effect relations between (pre-)historica phenomena and episodes of Rapid Climate Change (RCC). The 8.2 kya event is one of the most debated RCC in prehistoric archaeology of Western Asia and Europe, because it coincides with the expansion of agriculture and animal husbandry into Europe, facilitated through human migrations. If and how this momentous change in production economies, landscape use and demography, coinciding with a significant RCC, impact trophic ecosystems of terrestrial and marine fauna can, in theory, be addressed using the stable isotope analysis of animal remains from archaeological sites. The archaeological record, however, is not perfect. In this paper, we present the results of our research on a submerged anthropopogenic site at the border of the Aegean and the Black Sea, with stratigraphic layers dating to ca 8.2 kya event, and possibly of the establishment of the connection between the Black Sea and the Bosporus. We report on the combined results of zooarchaeological analysis and nitrogen, carbon, sulfur, and oxygen stable isotopic ratios on stratified animal bones and teeth.

Carbon, nitrogen, oxygen and sulphur isotopes in marine sediments have been widely used to study past environmental and climatic changes providing insights into biogeochemical cycles, oceanographic changes, and ecosystem responses. In this study, we utilize a suite of organic carbon CNS as well as bulk carbonate C and O isotope data in marine sediment cores from the Maldives archipelago to study local palaeoenvironmental, oceanographic and atmospheric changes related to past variability of the South Asian Monsoon (SAM). Our study focusses on a 6.2- and 5.1-million-year-old sedimentary sequence recovered from International Ocean Discovery Program (IODP) Site U1467. The recovered sediments were deposited during the time of the Messinian Salinity Crisis (MSC). The MSC was a significant hydrological event that occurred between 5.97 and 5.33 million years ago (Ma). During this period, the Mediterranean basin gradually dried out, leading to the formation of thick evaporite deposits as the connection to the Atlantic Ocean progressively closed.

The desiccation of the Mediterranean Sea during the MSC had a significant impact on regional Mediterranean climate dynamics and is further hypothesized to have even influenced global atmospheric circulation patterns, such as the position of the Intertropical Convergence Zone (ITCZ). Our study thus aims to test if SAM - a key global ocean-atmospheric system directly related to the ITCZ – was influenced by shifts in northern hemisphere pressure patterns, during the MSC.

Preliminary data shows elevated and muted δ¹⁸O_blkcarb values from ~5.8 Ma to the end of the MSC suggest strong evaporation and/or higher temperatures in the region. These findings provide new insights into the climatic and oceanographic response of the Maldives to MSC-driven shifts in monsoon dynamics.

The abundant quantities of well-preserved flax found in Egypt make this material a unique source of investigation for reconstructing the history of ancient Egyptian techniques and life. As a yearly-grown plant, it can be used as a reliable paleoclimatic archive. The ISOPALIN project proposes a multi-isotopic study of flax fibres found in archaeological contexts in Egypt, to document the growth media associated with this fibre through time. This project combines two different methodologies:

- A multi-isotopic study (²H, ¹³C, ¹⁸O) of flax cellulose using isotopic ratio mass spectrometry (IRMS), which is conducted at the Institute for Analytical Sciences (Lyon, France)

- An innovative study focused on ¹³C from flax cellulose using CO₂ laser spectroscopy (Off Axis Integrated Cavity Output Spectroscopy or OA-ICOS) to be implemented at the French Institute of Oriental Archaeology (Cairo, Egypt)

This combined methodology addresses several issues, including the link between post-burial degradation of linen artefacts and isotopic fractionation, the possibility for studying fibres provenance based on water isotopes, and ultimately, it allows us to document the growth environments associated with flax in ancient Egypt. Thanks to our two different approaches, this work will be articulated through isotope ratio mass spectrometry (IRMS) and CO2 laser spectroscopy, between France and Egypt, between fibre and sediment, and between modern linen samples, fragments from European museum collections and archaeological textiles found during recent excavations in Egypt. In this communication, the methodology and preliminary results will be detailed, and the importance of using isotopic instrumentation in Egypt will be highlighted.

The Southern Hemisphere Westerly Winds (SHW) play a key role in the global climate system, by regulating climate variability in Southern Hemisphere mid- and high-latitudes and by controlling deep water ventilation in the Southern Ocean (SO). The vigorous SHW strengthened and shifted poleward during the last decades of the 20^th century, contemporary with an increase in atmospheric temperatures, and enhanced SO CO₂ upwelling. This flux of ‘natural’ CO₂ to the atmosphere forms a potential amplification of human-induced global warming, as the strength of the SO CO₂ sink will weaken. In addition, a more poleward position of the wind belt, directly impacts human society as large areas on the three mid-latitude austral continents are exposed to droughts. Despite substantial research efforts during the last decades, our understanding of proxy-based knowledge on the strengthening and/or latitudinal shifts of the SHW is still fragmentary and sometimes contradicting. Here we present data on the Holocene evolution of the SHW from Amsterdam Island (37°S, Indian Ocean), located at the current northern edge of the SHW wind belt and part of a latitudinal transect of peat sequences from SO islands with Kerguelen and Crozet Islands at 49° and 46°S respectively. Rain-fed peat bogs occur on Amsterdam Island providing unique paleo-environmental archives. From those we will study the Holocene SHW variability in effective precipitation (precipitation minus evaporation) through bog surface wetness (BSW) proxies. We analysed stable hydrogen (δ²H) isotopes of plant derived n-alkanes to reconstruct water table depth and thus BSW. This isotopic record will be complemented with a macrofossil analysis, to assess possible species dependence of the δ²H record. Here we present preliminary results of this isotopic record and macrofossil analysis, along with a temperature record derived from the relative abundance of branched glycerol dialkyl glycerol tetraethers (brGDGTs), bacterial membrane lipids.

Paleoclimate research is important for understanding past, current and future climate, providing the data needed to model and predict current and future climate change scenarios. Stable isotope analysis provides an essential tool for gathering past climate information from natural archives such as waters including ice-cores, ground waters, and biological waters; and carbonate materials such as foraminifera and other fossilized carbonates. Due to the often limited and small sample sizes available for stable isotope analysis it is vital that highly precise and accurate analysis can be carried out on the smallest of sample sizes.

Dual inlet technology remains the most precise, accurate and sensitive technique for pure gas, carbonate and water analysis. The Elementar iso DUAL INLET is a valuable tool for paleoclimate applications, enabling the analysis of pure gas samples within an incredibly compact footprint via our powerful lyticOS software suite. The 14-ultra low dead volume valves with bodies machined from a single block of high purity stainless steel and dedicated turbomolecular pump for the changeover valve guarantees zero residual memory effects between reference and sample gas.

The iso DUAL INLET can be enhanced for automated analysis of carbonates and water samples. The iso AQUA PREP module analyzes up to 180 water samples with high precision for δ¹⁸O and δ²h. The iso CARB PREP module analyzes up to 180 micro-fossil samples for ¹³C and ¹⁸O, even with small sample sizes. The iso MULTI PREP module allows for both carbonate and water analysis with a simple needle change. The system can also be upgraded for "clumped isotope analysis" of carbonates.

We will highlight the performance of the iso DUAL INLET with carbonate and water functionality across a range of sample types for paleoclimate applications, supporting researchers building a detailed understanding of the past to better inform policy makers for the future.

Geochemical and biological records from lake and wetland sediments can be used to reconstruct past environmental conditions, providing insight into long-term climate variability and informing future climate predictions. Palaeoclimatic records produced in this way can also improve our understanding of how climate may affect landscapes and influence human behaviour both in the past and into the future.

Carbon and oxygen stable isotope measurements (ẟ¹³C and ẟ¹⁸O) of lacustrine carbonate are often used as a proxy to reconstruct past climate. Changes in lake systems can impact the amount of carbonate and organic matter (OM) preserved in the bulk sediment. Previous studies have documented that volatile components released from OM during phosphoric acid digestion of bulk sediment may impact the carbonate stable isotopic values. A commonly used method to remove OM from bulk sediment is pretreatment with sodium hypochlorite (‘bleach’), however care must be taken with sample pretreatment steps applied before carbonate stable isotope analysis, as the pretreatment itself may induce a bias in the carbonate ẟ¹³C and ẟ¹⁸O values. Previous studies have recommended that the suitability of pretreatment methods for OM removal be evaluated on a case-by-case basis.

Two small sets of sediment samples (from Loch Balnagowan in Scotland, and Gortnacrannagh wetland in Ireland) were pretreated for OM removal. Additionally, carbonate laboratory standards with different ẟ¹³C and ẟ¹⁸O values were pretreated, including across a series of pretreatment times. We report the carbon and oxygen stable isotope values following these pretreatment tests and discuss the implications of sodium hypochlorite pretreatment on bulk sediment from these systems.

Oxygen and hydrogen isotope ratios (d18O and d2H) are highly correlated in water sources, like precipitation and soil water, as they share the same isotopic fractionation processes, in particular evaporation. This water signal is in principle transferred to the cellulose of tree rings, which is the basis for climatic reconstructions using this archive. However, it has been observed that d2H variation in tree rings are often less well related to climate variations compared to d18O. Even sometimes an opposite pattern of the isotope ratios was observed – a decoupling. Recent studies have demonstrated that d2H is strongly influenced by biological processes and may be a proxy for physiological changes in carbon utilization, reflecting shifts between autotrophic and heterotrophic processes. These processes may be responsible for a decoupling occurring under certain situations. We highlight some of known decoupling examples, like the defoliation effect by the larch budmoth, an insect that regularly impacts larch (Larix decidua) trees in the Alps. We discuss how d2H variations may be a useful proxy for deciphering past environmental factors affecting the carbon metabolism of trees.

Stable oxygen isotope (δ18O) dendrochronology has recently emerged as a groundbreaking method for dating historic timbers that contain few tree rings or exhibit complacent growth (i.e., minimal year-to-year variation). In the continental Euro-Atlantic façade (from northwest Spain to northwest Germany), approximately 70% of timbers in historic buildings possess these characteristics, making them undatable with conventional ring-width dendrochronology. As a result, existing tree-ring datasets in this macro-region are predominantly composed of timbers with over 100 rings, as these are more likely to yield dates using traditional methods. This bias in dendrochronological records distorts studies on historical deforestation and construction activities, exaggerating building hiatuses and overemphasizing the role of timber trade in sustaining construction.

The ERC WoodCulture project (2025–2029) addresses this issue through the development of δ18O reference chronologies along the continental Euro-Atlantic façade for the period 1300–1600 CE. Preliminary results from the Netherlands demonstrate that δ18O can successfully date timbers with as few as 30 rings. Additionally, the first δ18O chronology for northwest Germany exhibits strong teleconnections with δ18O data recently produced in Belgium, though this correlation diminishes with the English δ18O chronology. These findings demonstrate the great potential of δ18O dendrochronology to date previously unstudied and undated timbers and highlights the need to expand reference chronologies across the continental Euro-Atlantic region.

This presentation will showcase these recent advances and the progress in developing δ18O reference chronologies for dating purposes, discussing several case studies. By enabling the study of wood from buildings, shipwrecks, and archaeological structures that were previously undatable, this research marks a crucial step toward redressing biases in dendrochronological databases and reshaping our understanding of past timber use and trade.

Doping control samples showing elevated urinary concentrations of testosterone or testosterone metabolites are forwarded to isotope ratio mass spectrometry-based determinations in order to differentiate between naturally elevated concentrations and doping offenses. The sample preparation encompasses liquid-liquid and solid phase extraction steps and enzymatic deconjugation of steroid glucuronides. In order to separate all steroid of interest from the biological matrix and to obtain sufficiently clean urinary extracts, high performance liquid chromatography (HPLC) with fraction collection is currently employed in routine doping controls. This preparation step is very time consuming as each HPLC run takes approx. 45 min and the evaporation of collected fractions containing water and acetonitrile lasts for up to 90 min.

Supercritical fluid chromatography (SFC) employs liquid carbon dioxide as eluent combined with other organic solvents like methanol or acetonitrile as modifiers. The unique physiochemical properties of liquid carbon dioxide enable to accelerate the chromatographic separation of different compounds and subsequently collected fractions only contain the modifier and additional methanol as make-up solvent which enables a very fast evaporation within 10 minutes.

Considering the potential benefits, a method was developed and validated in-line with current World Anti-Doping Agency-based regulations for doping control purposes encompassing testosterone, epitestosterone, dehydroepiandrosterone, androsterone, etiocholanolone, 5α- and 5β-androstanediol as target analytes and cholesterol, pregnanediol, 16-androstenol, and 11-oxo-etiocholanolone as endogenous reference compounds. An additional focus was set on potential isotopic fractionation during the SFC-based separation and the fraction collection process. Investigations into reference population derived carbon isotope ratios especially of cholesterol are still ongoing as this steroid has not been implemented into sports drug testing so far.

Keywords: supercritical fluid chromatography, fraction collection, chromatographic isotopic fractionation, doping controls, urinary steroids

For a long time, isotopic investigations are done to determine and guarantee the naturalness of commercial compounds claimed to be natural, such as flavours, essential oils, which are widely used in various industries (aromatherapy, cosmetics, food…). However, some suppliers are tempted to adulterate these expensive products by adding components of other origins to increase their financial profit. To address this issue, analytical controls are routinely carried out to guarantee authenticity, as consumers are sensitive to the origin of these products and are willing to pay more for natural origin.

While many forms of adulterations are well-known, fraud is still progressing in new areas where knowledge is quite limited, and identifying them requires increasingly complex solutions.

Here, we present 3 different studies that demonstrate how combinations of multi-isotopic approaches and molecular quantification can detect new types of adulterations in essential oil (EO):

- 1. Authentication of wintergreen EO: The naturalness of wintergreen EO was confirmed using a combination of hyphenated, ¹³C isotopic and molecular indicators. By comparing GC chromatograms, ¹³C and ¹⁴C measurements, a novel form of adulteration was identified, resulting from the addition of synthesised ¹⁴C-enriched molecule to mimic a natural raw material.

- 2. Differentiation of Neroli and Petitgrain EOs: Both EOs are derived from the bitter orange tree, with neroli obtained from its flowers and petit grain from its leaves. Although their molecular compositions are similar, their market prices differ significantly. Isotopic and molecular analyses were used to distinguish between them and identify potential adulterations.

- 3. Detection of semi-synthetic molecules: Semi-synthetic molecules, are natural equivalent molecules produced by chemical reactions. Limonene from sweet orange EO, cheaper to produce, is oxidised to carvone, which is the main component of spearmint EO. The most effective method to detect adulteration involves ¹⁸O GC-IRMS analysis unlike ¹⁴C dating or chiral methods.

Thai Hom Mali rice or Thai Jasmine rice, which has been registered under the European Protected Geographical Indication (PGI), is the most famous rice in the Thung Kula Rong Hai area in the northeast of Thailand. This is because of its unique characteristics, such as fragrant and smell like pandan leaves, especially if the rice was grown in the Thung Kula Rong Hai area in the northeast of Thailand. Thus, Thai Hom Mali rice has become a target for the unscrupulous producers to increase profits by mislabeling rice. In this study, the stable isotopic and elemental compositions including δ¹³C, δ¹⁵N, δ¹⁸O, δ²H, δ³⁴S, %C, %N %O, %H, and %S in Thai Hom Mali rice were analyzed using elemental analyzer isotope ratio mass spectrometer (EA-IRMS). Discrimination of the geographical origin of Thai Hom Mali rice cultivated in 5 provinces located in the Thung Kula Rong Hai area using stable isotopic and elemental compositions combined with multivariate analysis was demonstrated. The LDA for classification of the geographical origin of rice cultivated in 5 provinces in the Thung Kula Rong Hai area was achieved with 97.2% correct classification of their original groups and 72.2%.

This study is focused on the integration of stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) from blood plasma and erythrocytes, combined with metabolomic profiling, as a powerful tool to trace the dietary background of Iberian pigs. This approach enhances the capacity to authenticate this sustainable production system within the DEHESA ecosystem, ensuring the product quality and preventing fraud. The castrated Iberian pigs were initially fed maternal milk and commercial feed until the montanera period, during which they were divided into different groups according to the feeding regime followed: only acorns; acorns + concentrates; only concentrates. Blood samples were collected and subjected to stable isotope analysis of δ13C and δ15N using an EA-C-IRMS, while untargeted metabolomic profiling was performed using an UHPLC-HRMS/MS.
Stable isotope analysis revealed significant dietary effects on δ13C and δ15N values blood samples. ANOVA demonstrated significant impacts of sampling time on δ13C data. Metabolomic profiling identified distinct metabolic signatures associated with the diet. Acorn-fed pigs showed elevated levels of oleic acid and polyphenols related metabolites, while concentrate-fed pigs displayed markers linked to formulated feed, including altered lipid profiles and amino acid derivatives.
In summary, combining stable isotope analysis and metabolomics provides a robust approach to verify dietary practices in Iberian pig production. δ13C values on blood detects dietary shifts in short time, and metabolomics offers a detailed biochemical fingerprint of feed intake. Together, these methods could contribute to the fraud prevention, ensure product quality, and support sustainable dehesa ecosystem practices.

The demand of organic vegetables is mainly explained by consumers’ concerns about safety and perception that organically produced vegetable is safer and healthier than conventional vegetables. The aim of the study is to assess the preliminary data on stable nitrogen isotope as a screening tool to differentiate between organic and conventional growing vegetables. In this study, 180 samples of organically and conventionally grown vegetables that were obtained from various farms in Thailand were analyzed in order to determine if there are any differences in δ¹⁵N values. The results showed that there are significant differences (P < 0.001) in mean of δ¹⁵N values between organically and conventionally grown vegetables (8.99‰ ± 41%, n = 108 versus 0.44‰ ± 499%, n = 72). It is concluded that nitrogen isotope fingerprinting has the potential to enable authentication of organic vegetables.

　Stable isotope ratios have been used to authenticate and trace various food products. In the 2000s, liquid chromatography combined with isotope ratio mass spectrometry (LC/IRMS) was developed, enabling the measurement of stable carbon isotope ratio (δ¹³C) of highly polar and non-volatile analytes without derivatization. LC/IRMS has been applied to authenticate and trace products such as honey, wine, lemon juice, and alcohol beverage.

　As health awareness grows, health foods and dietary supplements have become readily available online. However, fraudulent activities, such as the mislabeling of geographical origin or ingredients, have been reported. In particular, naturally derived vitamin C supplements are several times more expensive than synthetic ones, resulting in mislabeling of ingredients.　Vitamin C supplements can be derived from two main sources: those synthesized industrially from sugarcane or corn, and those extracted from fruits (e.g., acerola, camu-camu). Therefore, a reliable method is needed to determine the origin of vitamin C supplements. In this study, we analyzed the δ¹³C values of ascorbic acid in vitamin C supplement products using LC/IRMS.

　First, we tested various types of analytical columns, eluents, pH levels, and column flow rates to establish a highly accurate analytical method of LC/IRMS. The optimized conditions were as follows: analytical column – Inert Sustain AQ-C18 (GL sciences inc.), column flow rate – 0.5 mL/min, and eluent – 0.1% phosphoric acid solution. We then applied the optimized method to more than 20 vitamin C supplement products. It was observed that natural vitamin C supplements products were more than 10‰ lighter than synthetic ones, providing a clear distinction. These results indicate that LC/IRMS is a powerful method for distinguishing synthetics from natural ascorbic acid in vitamin C supplements products.

Aminopolyphosphonates (APPs) are strong chelating agents have therefore been used since the 1980s to remove cations from reverse osmosis concentrates, as bleach stabilizers in detergents, and in paper and textile industries. However, possible risks of APP use such as eutrophication of natural waters, remobilization of heavy metals and formation of toxic transformation products (TPs) during degradation are not sufficiently known.

Therefore, we plan to investigate the oxidative degradation of three commonly used APPs – Aminotris(methylphosphonic acid) (ATMP), Ethylenediaminetetra(methylenephosphonic acid) (EDTMP), and Diethylenetriaminepenta(methylenephosphonic acid) (DTPMP) – via ozonation, persulfate oxidation, and percarbonate oxidation by coupling Liquid Chromatography-Isotope Ratio Mass Spectrometry (LC-IRMS) and LC-High Resolution Mass Spectrometry (HRMS) with a flow-splitter after LC-separation. This method was successfully developed for ATMP and its photolysis products by Marks et al.

To measure the isotopic fractionation of carbon during degradation, the LC-IRMS is used. By measuring isotopic fractionation of the educts, Rayleigh-plots that are characteristic for each degradation pathway can be obtained. Moreover, the extent of isotopic fractionation provides insight into the reaction mechanism as pronounced isotopic fractionation indicates a reaction at a carbon atom. To gain further insights into the degradation pathways and to identify TPs, a LC-HRMS system is needed as for LC-IRMS measurements all analytes are mineralized to CO₂.

Of the few well-known TPs, (Aminomethyl)phosphonic acid (AMPA) is of particular interest as it is genotoxic and more stable than the APPs. It is a TP of all APPs as well as of the herbicide glyphosate so that the origin of AMPA can likely be determined by LC-IRMS due to its isotopic composition. Moreover, glyphosate itself was proposed to be a TP of EDTMP and DTPMP. Therefore, the coupling method can be used to identify glyphosate in case it is formed and to distinguish between different degradation pathways and industrially produced glyphosate.

Consumers today are increasingly seeking products containing molecules of natural origin, as these are often perceived as healthier compared to their synthetic or semi-synthetic counterparts. However, the higher costs associated with the production of plant-based raw materials, as well as the extraction and purification of these natural substances, create opportunities for counterfeiting. This often involves the addition of cheaper, chemically indistinguishable synthetic forms. Techniques such as Stable Isotope Ratio Mass Spectrometry (SIRA) and Site-Specific Natural Isotope Fractionation by Nuclear Magnetic Resonance (SNIF-NMR) are valuable tools for distinguishing molecules of natural, biosynthetic, or synthetic origin across various categories, including flavorings, essential oils, foodstuffs, dietary supplements, pharmaceuticals, and steroids. While both methods are expensive and require specialized equipment, SNIF-NMR is less accessible and more complex than SIRA. However, it provides more detailed, site-specific molecular information. Despite the high precision and sensitivity of SNIF-NMR, SIRA offers broader scientific applications but is challenged by complex data interpretation and the limited availability of reference materials. Among isotopic parameters, δ²H measured by IRMS or (D/H)n determined via SNIF-NMR has demonstrated the greatest ability to discriminate, generally showing lower values in natural molecules and more positive ones in their synthetic counterparts. Although δ¹³C is the most extensively studied parameter, it does not always provide significant discrimination between natural and synthetic fossil-derived products. Nevertheless, it is particularly effective for differentiating natural molecules extracted from specific plants and their biosynthetic analogs, which are synthesized from C4 substrates such as sugarcane and corn (e.g., red yeast rice or L-theanine). In specific cases, δ¹⁵N (e.g., for caffeine) and δ¹⁸O (e.g., for Serenoa repens extract) have shown excellent potential for characterization.

GC/MS is a well-established technique that has been used in analytical laboratories for many decades, while GC/IRMS is a more recent method widely applied in the field of food traceability. In this work, we present the application of these two techniques in combination to assess the authenticity of certain high value food products.

Lavender essential oil is a high-value commodity used as a fragrance in cosmetics, as a flavoring component, and as a preservative in food and beverages. Due to its economic value, it is often substituted or blended with cheaper oils such as spike lavender, French lavender, and especially lavandin oils. The combination of these two techniques not only enables the distinction between lavender essential oil and lavandin oil based on VOC composition but also facilitates the identification of commercial samples adulterated with synthetic compounds through stable isotope analysis.

A similar approach was used to characterize menthol-based products: a wide variety of commodities were investigated in terms of their volatile/aromatic profile and stable isotope ratios in order to identify markers for distinguishing between synthetic and natural products. First, VOC extraction was carried out on several peppermint samples to establish reference isotopic values for natural products. Subsequently, various commercial products containing menthol were analyzed to verify the synthetic or natural origin of the menthol present in them. Samples like mint essential oils, toothpaste, mouthwash, candies, chewing gum, and syrups were considered in this study.

Manipulation of urine samples for drug testing or doping control analysis is a well-known problem, including dilution of urine, chemical adulteration or substitution by other liquids. Different analytical strategies have been developed to identify diluted or adulterated urine samples, as well as the identification of urine samples substituted with other liquids such as apple juice, alcohol-free beer, water or synthetic urine. Synthetic urine may contain different substances, including creatinine, uric acid and urea and show a specific gravity and pH similar to natural human urine samples. Several methods have been evolved within the last years to identify synthetic urine samples with routine analytical methods. These methods are based either on the identification of substance solely present in synthetic, but not natural urine, or on the identification of the absence of typically present urinary biomolecules.

In doping control analysis, the total absence of naturally occurring endogenous steroids (markers of the steroid profile) in a urine sample is strong evidence for a manipulated e.g. highly diluted or substituted sample. However, additional information supporting the assumption of a substitution of the original sample by synthetic urine can be particularly interesting.

A suspicious doping control urine sample without detectable amounts of endogenous steroids, a specific gravity of 1.014 and a pH of 8.3 revealed significant amounts of urea and protein. The urine sample was analyzed per EA/IRMS and the nitrogen and carbon isotopic composition of urea and total urine indicated a synthetic origin, similar to commercially available urea standards and synthetic urine. Compared to nitrogen and carbon stable isotope ratios of urine samples from a human reference population from Germany the suspicious doping control urine sample was clearly distinguishable.

The isotopic composition of CO can be used to detect enhanced oxidation of methane by atomic chlorine due to the strong kinetic isotope effect related to this reaction (KIE_CH4+Cl = 66 per mil). Importantly, this detection method has demonstrated the presence of a large ground-level North Atlantic chlorine source for the years 1996-1997, linked to the geographic distribution of iron-rich Sahara dust within the marine boundary layer (Mak et al., 2003; van Herpen et al., 2023). Here, we present 2023-2024 d¹³C_CO and d¹⁸O_CO data from an air sampling network established across the low-latitude Atlantic Ocean, including bi-weekly measurements from Tenerife (IEO and IZO), Cape Verde (CVAO), Barbados (RPB), and northern Brazil (ATTO). In addition, the network includes intermittent flask samples taken aboard commercial shipping vessels as they complete trans-Atlantic routes. Our analysis supports the existence of a large chlorine sink of methane in dust-associated regions, which varies seasonally. Underestimates in the occurrence of chlorine oxidation propagate to isotope-constrained top-down global methane models, shifting predicted contributions away from fossil fuels and towards biological sources. Ultimately, our results provide an opportunity to reconcile missing chlorine sources, which may have significant implications for global methane source estimations.

Sulfur compounds are vital to Earth's climate and air quality, with sulfate aerosols contributing to atmospheric cooling by scattering solar radiation. Their radiative effects are influenced by SO₂ oxidation pathways, which determine their properties. Since the 1980s, sulfur pollution in Lithuania has steadily declined, with SO₂ emissions decreasing at a faster rate than sulfate emissions. However, the sources and formation mechanisms of atmospheric sulfate remain uncertain. In this study, we analyzed the concentrations and sulfur isotopic compositions of SO₂ and PM₁ sulfate over a two-year period to identify pollution sources and sulfate formation pathways in Vilnius, Lithuania.

Distinct seasonal patterns were observed in the δ³⁴S values of SO₂ and sulfate, with lower δ³⁴S values during wintertime and higher δ³⁴S values in summer. Source apportionment of major regional pollution sources revealed, that biomass burning was the primary contributor to sulfur pollution in summer, while coal combustion emissions from neighboring countries were dominant in winter. During the winter of 2022–2023, heavy fuel oil (HFO) replaced natural gas at the local thermal power station in Vilnius, making HFO emissions a significant source of SO₂ and PM₁ sulfate during this period. Additionally, during the 2022-2023 winter period, the predominant sulfate production mechanisms were evaluated, revealing that SO₂ oxidation by O₂, catalyzed with transition metal ions, was the primary mechanism, accounting for 79 ± 7 %, while oxidation by OH radicals and H₂O₂ contributed 5 ± 5 % and 16 ± 7 %, respectively.

The dual isotopic composition of CH₄ (δ¹³C-CH₄, δD-CH₄) holds potential to differentiate between fossil fuel-related, microbial and pyrogenic sources. Separation between thermogenic and biogenic processes can be supported by the analysis of co-emitted species, such as ethane (C₂H₆), which is formed during thermal cracking of sedimentary organic matter, while microbial formation practically lacks ethane emissions.

In this study, we present high-resolution measurements of δ¹³C- and δD-CH₄ by a customized preconcentration (TREX) - laser spectroscopy (Aerodyne Research Inc.) system, δ¹³C-CH₄ by commercial cavity ring-down analyzer (G2201-I, Picarro Inc.) and C₂H₆ / CH₄ by a compact laser spectrometer (Aeris Technologies Inc.) in ambient air sampled at a suburban site close to Zürich, Switzerland. We show performance characterization, i.e. temporal resolution, precision, repeatability and comparability of techniques in relation to WMO/GAW (Word Meteorological Organization/Global Atmosphere Watch) requirements for monitoring atmospheric composition in regions with significant local fluxes. Furthermore, the temporal variations in CH₄ isotopic composition and C₂H₆ / CH₄ are interpreted by using the Keeling-plot or mixing-model approach.

We use atmospheric transport modelling and a sectorial CH₄ emission inventory to simulate CH₄, its isotopic composition and C₂H₆ / CH₄ at the site. We compare analytical results with these simulations with a focus on validating the applied regional emissions. By analyzing individual events, we identify periods and regions where isotopic observations can inform emission estimates.

We present semi-continuous stable isotope composition measurements of atmospheric CO₂, including the triple oxygen isotope composition or Δ¹⁷O, in a record spanning the end of 2024 until spring 2025. Measurements are conducted with an Aerodyne dual-laser absorption spectrometer which was installed at the Lutjewad atmospheric measurement station, located at the North coast of the Netherlands. Atmospheric air coming from the 60 m high tower is measured as discrete samples, continuously alternated with measurements of a working gas for drift correction. Reference cylinders covering the range of CO₂ amount fractions occurring in the atmospheric samples are measured for calibration of the isotopologue amount fraction measurements.

The Δ¹⁷O measurements typically have a standard deviation of 0.06 ‰ for a single gas measurement, and the long-term stability is 0.04 ‰. Multiple tracers are measured at the Lutjewad station, including CO₂, H₂ and N₂O amount fractions as well as the δ¹³C and δ¹⁸O composition of atmospheric CO₂. This gives us the opportunity to explore the potential of the Δ¹⁷O of atmospheric CO₂ for carbon cycle research, for instance by studying the coupling with biosphere activity and fossil fuel combustion. In this project we have a special focus on the potential correlation between positive Δ¹⁷O anomalies and stratospheric intrusions, and first results of these analyses will be presented on the poster.

Methane (CH₄) plays a crucial role in the global carbon cycle and is the second most significant anthropogenic greenhouse gas after CO₂. The current global methane mole fraction in the atmospheric is 2.5 times higher than pre-industrial levels. The isotopic signatures of methane, δ¹³C-CH₄ and δD-CH₄, are valuable tools for identifying sources and tracking its atmospheric pathway. However, discrepancies persist between measured and simulated δ¹³C-CH₄ values, with a wide uncertainty being the kinetic isotope effect (KIE) associated with the reaction between CH₄ and hydroxyl radicals (OH·)—the primary atmospheric sink for methane. Reported KIE values for this reaction vary, with previous studies reporting ^13CKIE ranging from 1.0054 to 1.0039, and ^DKIE ranging from 1.294 to 1.25. These variations contribute to significant uncertainty in the global methane isotope budget, underscoring the need for more precise KIE determinations to improve CH₄ source attribution.

To address this, this study aims to refine KIE measurements by conducting controlled laboratory experiments in which CH₄ reacts with OH· radicals. The hydroxyl radicals are produced via the photolysis of hydrogen peroxide (H₂O₂) using a deep-UV light source (200–380 nm). The reactions occur in a triple-quartz-layered reactor under stable pressure and temperature conditions, with secondary products removed via low-temperature trapping. The reactor is directly connected to two Isotope Ratio Mass Spectrometers (IRMS), allowing for continuous, high-precision measurements of δ¹³C, δD, and δ¹⁸O in the remaining CH₄ and CO throughout the photochemical experiments.

The oxidative capacity of the atmosphere and its implication in past and present climate changes remain poorly understood. In that perspective, better understanding the chemistry of atmospheric oxyanions like nitrate and sulphate is key, as they are the stable end products of oxidation reactions. In oxyanions, isotope clumping —the likelihood of multiple isotopic substitutions in the same molecule— is anticipated to be sensitive to the oxidation pathway involved in molecule formation. Accessing clumping information requires measuring the scarce doubly-substituted isotopologues.

The recent Orbitrap mass spectrometers combined with electrospray ionisation allow measurements on intact ions at high mass resolution, conserving the intra-molecular clumping information and discriminating the doubly-substituted isotopologue peaks. While this novel method provides promising results for nitrate isotopologues, measuring sulphate isotopologues remains challenging.

One way to measure sulphate isotopologues with ESI-Orbitrap is to analyse them as HSO4- anions. However, the isobaric interference between DSO4- and HS17OO3- isotopologues leads to inconsistent results for 17O or requires a drastic increase in resolution, which is detrimental to the precision of all sulphate isotopologue measurements. An alternative approach involves breaking the HSO4- anions into SO3- fragments, which eliminates this issue and requires lower mass resolution. This can be achieved by using higher-energy collisional dissociation —where the accelerated ions collide with nitrogen molecules— converting 90% of HSO4- into SO3- fragments which keep a satisfactory base peek intensity. We applied this method to several standards and natural samples and found that it provides better results both in terms of precision and accuracy for singly-substituted isotopologues, including 17O, compared to the previous method. We also measured doubly-substituted isotopologues, yet the question of which method is best for this purpose remains open.

Particulate air pollution, particularly carbonaceous aerosols like black carbon (BC), significantly impacts urban air quality and human health. BC, emitted from incomplete combustion of carbonaceous fuels, is a key indicator of anthropogenic sources and CO₂ emissions. While spectrally resolved aerosol absorption measurements help distinguish between traffic and biomass burning sources, stable carbon isotope analysis of CO₂ provides insights into gaseous CO₂ sources.

This study combines stable carbon isotope analysis of CO₂ with highly time-resolved BC measurements to distinguish between different sources, providing valuable insights into the contributions and timings of various sources, gas and particles, to air pollution

Method for air CO₂ stable isotope composition using Continuous Flow IRMS approach developed as part of the SIRS project was compared with the “golden standard” in atmospheric researches Dual Inlet IRMS approach compared with measurements performed during the CCQM P-204 pilot study. A real-world application was tested in the STRAP project.

From July to September, CO₂ concentrations and BC from wood-burning and traffic sources revealed distinct daily patterns. Traffic emissions caused morning BC peaks, while midday atmospheric mixing reduced BC and CO₂ concentrations, followed by pollutant accumulation in the afternoon. A two-hour lag was observed between BC and CO₂ morning peaks, reflecting their distinct emission dynamics. Ultrafine particles (UFP) mirrored BC’s behaviour, indicating a combustion origin. Lower δ¹³C values (down to −15 ‰) during high CO₂ concentrations further confirmed anthropogenic sources.

These findings highlight the importance of continuous monitoring and advanced analytical methods to better understand and address air pollution in urban and rural settings.

The COVID-19 pandemic led to significant air quality changes due to lockdowns. While PM_2.5 reductions were observed in many regions, long-term trends and variations in sources remain unclear, especially in Dhaka, Bangladesh, which records some of the highest PM_2.5 levels globally. Understanding PM_2.5 sources is essential for air quality management, pollution mitigation, and public health, as exposure to fine particulate matter is linked to severe respiratory diseases and cardiovascular problems.

This study analyzed PM_2.5 samples collected in Dhaka after COVID-19 to examine trends in water-soluble ions and nitrogen stable isotope ratios of ammonium (δ¹⁵N-NH₄⁺) and nitrate (δ¹⁵N-NO₃⁻, δ¹⁸O-NO₃⁻). PM_2.5 concentration data were obtained from EPA AirNow. Water-soluble anions (Cl⁻, NO₂⁻, NO₃⁻, SO₄²⁻) and cations (Na⁺, NH₄⁺, K⁺, Mg²⁺, Ca²⁺) were analyzed using ion chromatography. δ¹⁵N-NH₄⁺ was measured using solid-phase extraction and the bacterial denitrification method (Kawashima et al., 2021), while δ¹⁵N-NO₃⁻ and δ¹⁸O-NO₃⁻ were analyzed via bacterial denitrification method.

PM_2.5 concentrations increased annually from 86.2 μg/m³ (2019) to 103.6 μg/m³ (2023). During the lockdown (March–May 2020), PM_2.5 levels (69.8 μg/m³) were lower than in 2019 (53.7 μg/m³, a 23% reduction), indicating a temporary decline in emissions. However, post-pandemic, PM_2.5 rebounded due to resumed economic activities, increased industrial output, and biomass burning. The δ¹⁵N-NH₄⁺ values decreased (21.3‰ in 2019 to 12.3‰ in 2022), suggesting increased agricultural contributions, particularly from fertilizer and livestock waste.

Similarly, δ¹⁵N-NO₃⁻ values declined slightly, indicating changes in NO₃⁻ sources, while δ¹⁸O-NO₃⁻ remained stable. These shifts may be linked to environmental policies, such as converting Fixed Chimney Kilns to ZigZag Kilns, reducing emissions. This study highlights the importance of stable isotope analysis in pollution source identification. Future research should investigate seasonal variations and meteorological influences on nitrogen isotopes to improve air quality policies and public health interventions.

Methane (CH₄) is the second most important anthropogenic greenhouse gas, with a global warming potential 84 times greater than carbon dioxide (CO₂) over a 20-year period. In recent years, atmospheric CH₄ concentrations have accelerated rapidly, with δ¹³CH₄ measurements indicating a notable shift towards biogenic emissions. However, significant uncertainties persist regarding the relative contributions of sinks and sources to observed CH₄ and δ¹³CH₄ trends, complicating efforts to pinpoint the drivers of methane growth and improve predictions of the methane budget under future climate change scenarios.

In this study, we employ the Miller-Tans method to determine the δ¹³CH₄ source signature for regional methane emissions, utilizing long-term atmospheric CH₄ and δ¹³CH₄ observations from the NOAA Global Monitoring Laboratory (GML) sampling network and optimised CH₄ and δ¹³CH₄ model fields from a latest global inverse model. We conduct detailed analysis of the spatial distribution, seasonal variations, and long-term trends of the δ¹³CH₄ source signature time series. Our analysis reveals a significant trend towards lower source signature from tropical to high northern latitudes. A clear seasonal cycle in source signature is observed at the high latitude stations. Our analysis also shows that this is not limited to a single site but represents a common and persistent feature at high northern latitudes. These results suggest that biogenic emissions are increasingly influential in driving atmospheric methane levels at high northern latitudes. These findings provide new insights into the processes governing atmospheric CH₄ and δ¹³CH₄ variations and assess how accurately contemporary inverse models reproduce these observed changes.

Monitoring greenhouse gas exchange between land ecosystems and the atmosphere using the eddy covariance technique has become standard practice in many flux observation networks. However, studies on stable isotope fluxes remain scarce and are typically limited in their temporal extent, despite their importance at contributing to accurate partitioning of fluxes. As part of the ISOMONEAE project, we designed a setup for eddy covariance measurements of CO₂ and H₂O stable isotopologues, which will be active over a two-year period from 2025 to 2027 in a managed beech forest in central Germany. The primary objective of the project is to investigate whether and how continuous, long-term, high-frequency isotopologue flux measurements can provide valuable additions to existing flux observation networks such as ICOS or FLUXNET.

Here, we present a novel setup for CO₂ and H₂O isotopologue eddy covariance measurements, utilizing an Aerodyne quantum cascade laser absorption spectrometer (Aerodyne Research Inc.) for CO₂ and an LGR absorption spectrometer (Los Gatos Research (ABB Inc.)) for H₂O. Ongoing work includes characterizing and enhancing instrument performance and designing automated calibration systems necessary for accurate long-term measurements. The instruments were characterized based on their drift behavior, time response, and measurement linearity. Through these investigations we identified temperature and pressure fluctuations as major sources of drift. To mitigate these effects, we designed automated calibration systems that perform hourly calibrations to maintain accuracy and precision.

We believe our projects outcome represents a significant step towards the implementation of large-scale, continuous, long-term, high-frequency isotopologue eddy covariance measurements into existing flux observation networks. The results will enhance our understanding of ecosystem-atmosphere exchange processes by disentangling greenhouse gas sources and sinks in ecosystems.

Quantifying the sources and sinks of CO₂ is crucial to constrain the global carbon budget, where very precise measurements of the mole fraction and isotopic composition of carbon dioxide are required. Additionally, global monitoring by analysing air samples from various locations is necessary to monitor (regional) trends. An increasingly used technique for measuring isotopic composition is laser spectroscopy, which is fast and precise.

In this study, an Aerodyne TILDAS Compact Single Laser CO₂ Isotope Analyzer was characterized and calibrated. As part of this, different measurement conditions, such as measurement pressure and time, were tuned to achieve the highest precisions. During the past year a measurement procedure was developed to analyse air samples. The samples were collected at various ground stations worldwide and along the Atlantic transect using ships and the mole fraction and isotopic composition of CO₂ (δ¹³C and δ¹⁸O) were measured. The ground-based sampling stations include Cape Verde, Tenerife (IEO and IZO), Barbados (RPB), the Amazon Tall Tower Observatory (ATTO), Zeppelin Observatory (ZEP) and Monte Cimone (ICOS station). The measurements achieved mean precisions of 0.03‰ and even up to 0.01‰ for δ¹³C and δ¹⁸O, comparable to gas source isotope ratio mass spectrometry, and 0.08 ppm for CO₂ mole fraction.

Our time series reveal a clear seasonal trend, with bigger seasonal variations in poleward regions (e.g. ZEP), where photosynthesis and respiration processes exhibit the greatest fluctuations seasonally. In contrast, smaller variations are recorded near the equator (e.g. Cape Verde), where vegetation coverages remains relatively stable throughout the year. Similarly, we observe a latitudinal gradient in CO₂ mole fraction and isotopic composition obtained from the ship transects.

To reduce uncertainties in the global carbon cycle, further long-term measurements are needed to extend the dataset and improve our understanding of seasonal and spatial CO₂ variations.

The sulfur mass-independent fractionation (S-MIF) anomaly in sulfate records from ice cores, marine, and terrestrial archives has become a valuable geochemical tracer. However, significant uncertainties remain about the mechanisms that generate S-MIF, which complicates the interpretation of these measurements. The most widely invoked mechanism involves the exposure of sulfur gases to high levels of UV radiation. In this study, we present the development of a balloon-borne aerosol sampler, StratoPart, designed to collect sulfate on filters in the stratosphere - an environment with high UV radiation where the largest S-MIF anomalies in sulfate are expected to be found. The goal is to analyse the collected stratospheric sulfate to investigate and test the various proposed mechanisms for terrestrial sulfate S-MIF anomalies. StratoPart was flown during two balloon campaigns in the summer of 2024: one operated by CNES in Kiruna, Sweden, and the other by the TiFR balloon facility in Hyderabad, India. We will share preliminary results from the chemical analysis of some of the filters collected during these campaigns and discuss their implications.

Methane (CH₄) mitigation is crucial for climate change mitigation, as it is a potent greenhouse gas with a shorter lifetime compared to CO₂. This, however, requires a solid understanding of the CH₄ sources. Isotopic analysis can aid in source partitioning.

CH₄ isotopic source signatures obtained through mobile measurements are limited to short durations and often fail to capture smaller or previously unknown emissions. In contrast, continuous CH₄ measurements cover longer periods and can detect inaccessible or unknown sources. These continuous measurements are unfortunately costly and it is more challenging to identify the source.

Researchers at Utrecht University developed an isotope ratio mass spectrometer system that measures CH₄ mole fraction, δD and δ¹³C at high precision (δ¹³C ± .2 ‰ δD ± 1 ‰) with a 40-minute resolution. This system was deployed from 15 April 2022 until 8 January 2023 in Lindenberg, Germany. Measurements were initialised at 40 meters and later continued at 98 meters. The station is part of the Integrated Carbon Observation System (ICOS), providing mole fraction measurements of CO, CO₂, and CH₄. The CH₄ measurements were also compared with simulations from EMPA. These simulations include the CH₄ emissions for each category, allowing us to assign an isotopic source signature to each emissions category, thereby simulating the δD and δ¹³C of CH₄.

In the isotopic measurements, we observed 169 peaks related to diurnal elevations. This corresponds to 67% of the deployment days. Most source signatures indicate a microbial fermentation source. Additionally, we identified 19 multi-day elevations. Eight multi-day elevations displayed isotopic signatures similar to those of the diurnal peaks, while the remaining multi-day peaks were more distinct.

In short: this dataset with continuous CH₄ δD and δ¹³C measurements enables the characterization of diurnal elevations and multi-day emissions and can show the quality of transport models.

Quantification of greenhouse gas (GHG) emissions are required for the mitigation strategies to be effectively made. Top-down methods, one of the efforts to improve our estimation, utilise ambient GHG measurements and atmospheric transport models (ATMs) on top of the prior flux estimates. A network of isotopic measurements of methane (δ13C-CH4 and δ2H-CH4) across Europe is starting to get developed, which has been identified as tracers to allow us to differentiate different sources categories within regional scale.

This work aims to show how the two components of the top-down methods, ATMs and prior flux estimates contribute towards uncertainties in the initial modelled observations to compare it with the uncertainties in our measurements. We model for 6 European sites (Heathfield, UK; Heidelberg, Germany; Lindenberg, Germany; Lutjewad, Netherlands; Mace Head, Ireland; and Tacolneston; UK), some of which have high frequency isotope measurements, using two ACTMs and their associated meteorology: NAME with the UK Met Office Unified Model; and FLEXPART with ECMWF IFS analysis and short-term forecasts, and an ensemble of prior fluxes created from their assigned uncertainties.

The methane clumped isotope approach measures differences in abundances of doubly substituted species, i.e. ¹³CH₃D and ¹²CH₂D₂, relative to the expected stochastic distribution of atoms. The resulting Δ¹³CH₃D and Δ¹²CH₂D₂ serve as proxy for formation temperature under thermodynamic equilibrium, while departure from equilibrium indicates contributions of kinetically controlled CH₄ formation and consumption mechanisms, as well as other post-generation processes. Due to the extremely low abundance of doubly substituted isotopologues, highly advanced techniques are required.

In recent years, we established a spectroscopic platform based on quantum cascade laser absorption spectroscopy (QCLAS), with optimized spectral windows for clumped isotope analysis and a custom-built gas inlet system. The developed technique offers the feasibility of reducing sample size down to 3–7 mL CH₄ gas while achieving precision levels comparable to HR-IRMS. Samples larger than 10 mL can be quantified in a single run in under 20 min.

By leveraging this rapid, high-throughput QCLAS method, we explored several prototype applications. In a comprehensive technical study, we optimized the selection and use of cryogenic adsorbents for CH₄ storage targeting conservation of bulk and clumped isotopic signatures. As an illustrative and relevant geological application, we extract thermogenic CH₄ entrapped in the porosity of the source rocks to test whether CH₄ has formed under thermodynamic equilibrium. CH₄ clumped signatures of bubble gases collected from various mud volcanoes and hybrid systems in Italy and Indonesia can provide valuable insights into the mixing of thermogenic CH₄ with secondary microbial CH₄ and enzyme-catalyzed isotope exchange. We also investigate the clumped isotopic fingerprint of CH₄ originating from iron-oxido mediated formation of methyl radicals from methyl-substituted substrates, which might be a common abiotic source for C1 and C2 compounds. Our presentation will showcase the potential of the spectroscopic technique to be a more practical tool for analyzing methane clumped isotope signatures.

Keywords: biomass burning, aerosol, isotopic analysis.

Biomass burning contributes to atmospheric aerosols, emitting a variety of particles and gases that impact both local and global air quality, as well as climate systems. This research examines aerosols produced from different wood species and coal, focusing on their isotopic signatures for total carbon under both controlled and uncontrolled experimental conditions. The study involved two distinct setups. First experiment was designed to simulate typical domestic heating practices during winter (in Lithuania). Second experiment was set up with controlled conditions as well as assessing the mass and humidity of biomass material and coal before monitoring of O₂, CO₂, temperature, airflow, pressure, η, λ, NO , CO and NO₂ levels of the smoke. A high flow (0.5 m3/min) sampler „DIGITEL DH-77” with a pre-separator “DPM 10/30/00” was used to collect biomass burning organic aerosol (BBOA) from the smoke on Whatman QM-A pure quartz fiber filters “Pallflex Tissuquartz 2500QAT-UP” of 150 mm diameter. The δ¹³C values of bulk material (δ¹³C_TC) and total carbon of OA were determined at Center for Physical Sciences and Technology, Vilnius, Lithuania. The analysis was conducted using an elemental analyzer ("Flash EA 1112") coupled to an isotope ratio mass spectrometer ("Thermo Finnigan Delta Plus Advantage") via a "ConFlo III" interface (EA–IRMS system). A 1cm diameter round punch of the filter containing aerosol particles was wrapped in a tin capsule and introduced into the EA–IRMS system for measurement. The isotopic signatures and fractionation factors were observed to vary between controlled and uncontrolled settings, providing insights into how variations in environmental factors affect aerosol composition. This study enhances understanding of the aerosol formation under idealized conditions and real-world burning scenarios, thus providing deeper insights into the environmental effects of biomass burning.