Search results

本稿では，まず陸域と水域の一次生産者から有機物を得る混合生態系の解析のために，メチオニンの窒素安定同位体比（δ15NMet）の指標としての有効性を検討した．陸域生態系におけるメチオニンとフェニルアラニンの同位体比の差（ΔMet-Phe＝−16.5±0.5‰）と水域生態系における差（ΔMet-Phe＝−5.0±0.5‰）は明確に区別されることがわかった．次に，ガスクロマトグラフィー/燃焼/同位体比質量測定法（GC/C/IRMS），液体クロマトグラフィー（LC） × 元素分析計/IRMS（LC × EA/IRMS），LC × GC/C/IRMSの3手法を比較した．魚類筋肉のグルタミン酸（δ15NGlu）とフェニルアラニン（δ15NPhe）値はすべての測定法のペアでほぼ一致していた．さらに，アミノ酸の放射性炭素濃度（Δ14C）測定のための単離・精製方法を改良し，EA/加速器質量分析装置（EA/AMS）を用いて測定を行った結果，標準物質ではΔ14C測定値と既知のΔ14C値がよく一致した．

Honey is one of the most valuable sweeteners consumed by humans all over the world. Consequently, it is often a target for adulteration through the addition of different sugar syrups during or after ... honey production, resulting in a reduction in its nutritive value. For the first time, this study analyzes honey samples of various botanical species collected from different Lebanese regions using element analyzer (EA) and liquid chromatography (LC) coupled with isotope ratio mass spectrometry (IRMS). The δ13C of bulk honey, its protein fraction, and the main individual sugars (glucose, fructose, disaccharides, and trisaccharide) were determined, in order to characterize and evaluate the authenticity of honey consumed in Lebanon. The results showed that the δ13C values for bulk honey and its protein range from −26.5‰ to −24.5‰ and from −26.4‰ to −24.7‰, respectively, for authentic samples. δ13C values for samples adulterated with sugar syrups range from −11.2‰ to −25.1‰ for bulk honey and from −26.6‰ to −23.7‰ for its proteins, with a difference between bulk and protein values between −1 and −8.7‰. Using LC‐C‐IRMS techniques, the δ13C of individual sugars provides additional information on the presence of undeclared sugars. We found that all authentic samples had Δδ13Cf‐g and Δδ13C max values within the naturally occurring range of ±1‰ and ±2.1‰, respectively, while the adulterated samples fall outside the Δδ13C ranges. The oligosaccharide peak was detected in most adulterated samples. more

A comprehensive understanding of carbon cycling pathways in the soil-plant system is needed to develop models that accurately predict global carbon reservoir responses to anthropogenic perturbations. ... Honey is a carbon-rich natural food produced by wild and managed pollinating insects all over the world; the composition of a single sample is a function of millions of pollinator-plant interactions. We studied the 13C/12C and Δ14C of 121 honey samples sourced from the United States, and found a significant older carbon contribution. The effect is observed from 25 to 45° latitude, not correlated with 13C/12C, and consistent with a previously published study on European honeys. In specific cases, the measured values were up to 20 ‰ (Δ14C) higher than the expected atmospheric 14CO2 value for the given year, which shows a significant older carbon contribution. We hypothesize that the older carbon is from plant liquids derived in part from soil carbon or stored nonstructural carbohydrates from plants, which shifts the calibrated age of the sample by 5 years or more. Our work is the first to describe the widespread occurrence of older carbon in honey and shows that radiocarbon measurements can be a powerful tool to trace carbon allocations in terrestrial food webs and detect the atmosphere-soil-plant carbon cycle contributions. Display omitted •Radiocarbon analysis of honey samples from North America•Honey shows a mixture of fresh and aged carbon across a large region.•GIS analysis showed that the 14C offset cannot be attributed to power plants.•Honey is useful for observing natural plant carbon allocations.•Radiocarbon ages may be overestimated from soil carbon inputs. more

This article is a summary of three of the author’s previous studies12)20)29). Compound-specific isotope analysis of nitrogen (δ15N) and radiocarbon (Δ14C) analyses of amino acids (AAs) have ... significantly contributed to environmental sciences such as anthropology, biogeochemistry, and ecology. To study mixed ecosystems where basal resources are derived from both terrestrial and aquatic primary producers, the δ15N of methionine (δ15NMet) was determined. The results showed that the difference in δ15N between methionine and phenylalanine in terrestrial ecosystems (ΔMet–Phe = –16.5±0.5‰) is clearly distinguishable from that in aquatic ecosystems (ΔMet–Phe = –5.0±0.5‰). Next, AA δ15N values were systematically compared among three methods using gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS), preparative liquid chromatography (LC) separation followed by elemental analyzer/IRMS (LC × EA/IRMS), and LC separation followed by GC/C/IRMS (LC × GC/C/IRMS). The δ15N values of glutamic acid (δ15NGlu) and Phe (δ15NPhe) in fish muscle were fairly consistent between all pairs of methods. Finally, the isolation and purification method of AAs for Δ14C analysis was improved. The AA Δ14C values determined by EA/accelerator mass spectrometry (EA/AMS) were in strong agreement with the consensus Δ14C value of each amino acid standard. more

•Honeys with non-extractable protein were evaluated systematically for the first time.•EA-IRMS and LC-IRMS were suitable for measurement of adulteration in honeys.•Honeys with non-extractable protein ... were all identified as adulterated with C-4 or C-3 sugars.•Large numbers of samples were analyzed to ensure reliability.•Result obtained is highly recommended as a supplement to AOAC 998.12 method. The present work aims to systematically demonstrate the authenticity of honeys with non-extractable proteins for the first time, by means of EA-IRMS and LC-IRMS. Fifty-three pure honeys of various botanical and geographical origins were studied and a criterion on the basis of the stable carbon isotope ratio characterization of total honey and the main sugars was established for pure honeys. Parameters such as δ13C values of total honey and the main sugars were well utilized to identify honeys with non-extractable proteins. Thirty-five honeys from which protein could not be extracted were all identified as adulterated with C-4 sugars or C-3 sugars. The use of isotopic compositions and some systematic differences permit the honeys with non-extractable proteins to be reliably identified. The findings obtained in this work could supplement the AOAC 998.12 C-4 sugar method, with regard to honeys from which protein cannot be extracted. more

An increasing amount of organic micropollutants (OMPs) are detected in aquatic environments and occur in water supplies worldwide. OMPs pose a severe threat to freshwater resources and present a ... potential danger to ecosystems and human health, even at trace concentrations. Compound-specific isotope analysis (CSIA) is one of the key techniques for identifying the origin and fate of environmental pollutants in aquifers and for characterizing their transformation processes. Considered as relatively mature for environmental monitoring of some well-studied industrial hydrocarbons at contaminated sites, the technique still encounters many analytical challenges in the context of diffuse pollution for other organic compounds. The present review provides a comprehensive overview on the latest technical developments concerning isotope ratio analyses of OMPs such as pesticides, various industrial compounds, pharmaceuticals and personal care products (PPCPs), and nitroaromatic compounds and organic explosives (NACs/OEs). Based on a compilation of nearly 200 CSIA-studies of OMPs, we describe the analytical challenges and address common pitfalls that can be encountered in a context of diffuse pollution in wastewater, surface waters or groundwater. Our work gives an update on instrumental developments and advances in analytical approaches for CSIA-techniques for carbon, nitrogen, hydrogen, and chlorine stable isotopes. Furthermore, the review accounts for perspectives provided by associated innovations, such as sample processing for CSIA applications of the different OMPs in the context of diffuse pollution in aquatic environments. •Organic micropollutants (OMPs) in the aquatic environment are of increasing concern.•CSIA has great potential for evaluating the environmental fate of micropollutants.•Critical assessment of the latest analytical advances in CSIA applied to diffuse pollution.•Recent advances in extraction techniques improve feasibility of micropollutant CSIA.•CSIA applied at catchment scale depends on general advances in analytical chemistry. more

The feasibility of using δ(15) N as an additional isotopic marker able to link wine to its area of origin was investigated. The whole production chain (soil-leaves-grape-wine) was considered. ... Moreover, the research included evaluation of the effect of the fermentation process, the use of different types of yeast and white and red vinification, the addition of nitrogen adjuvants and ultrasound lysis simulating wine ageing. The δ(15) N of grapes and wine was measured in bulk samples and compounds, specifically in proline, for the first time. Despite isotopic fractionation from soil to wine, the δ(15) N values of leaves, grapes, wine and particularly must and wine proline conserved the variability of δ(15) N in the growing soil. Fermentation and ultrasound treatment did not affect the δ(15) N values of grape must, which was therefore conserved in wine. The addition of inorganic or organic adjuvants was able to influence the δ(15) N of bulk wine, depending on the amount and the difference between the δ(15) N of must and that of the adjuvant. The δ(15) N of wine proline was not influenced by adjuvant addition and is therefore the best marker for tracing the geographical origin of wine. Copyright © 2016 John Wiley & Sons, Ltd. more

In our earlier publications we proposed the possibility of using new EIM–IRMS ® instrumental technique and analytical parameter δD n wine ethanol, which represents δ 2 H value of non-exchangeable ... hydrogen stable isotope ratio in ethanol, to improve detection of illegal wine production practices such as addition of sugar and/or water to grape must prior to alcoholic fermentation. This article shows a comparative performance study between EIM-IRMS ® and CS-qNMR methods in order to evaluate potential and demonstrate the precision of two isotopic concepts and their degree of detection of illegal wine production practices. Three batches of laboratory wine samples were prepared from three different types of grapes ( N =24 samples). Sample results obtained from both methods are compared and a statistical data processing was carried out. Based on the results obtained using the EIM-IRMS ® method we detected 11 out of 21 of previously adulterated wine samples which represents a success rate of 52.4% detection of illegal practices (beet sugar, water or beet sugar syrup additions). In addition, wines from the Republic of Serbia (90 samples) were examined as well using the EIM-IRMS ® method and appropriate equipment to confirm their authenticity. more

The feasibility of using δ15N as an additional isotopic marker able to link wine to its area of origin was investigated. The whole production chain (soil–leaves–grape–wine) was considered. Moreover, ... the research included evaluation of the effect of the fermentation process, the use of different types of yeast and white and red vinification, the addition of nitrogen adjuvants and ultrasound lysis simulating wine ageing. The δ15N of grapes and wine was measured in bulk samples and compounds, specifically in proline, for the first time. Despite isotopic fractionation from soil to wine, the δ15N values of leaves, grapes, wine and particularly must and wine proline conserved the variability of δ15N in the growing soil. Fermentation and ultrasound treatment did not affect the δ15N values of grape must, which was therefore conserved in wine. The addition of inorganic or organic adjuvants was able to influence the δ15N of bulk wine, depending on the amount and the difference between the δ15N of must and that of the adjuvant. The δ15N of wine proline was not influenced by adjuvant addition and is therefore the best marker for tracing the geographical origin of wine. Copyright © 2016 John Wiley & Sons, Ltd. more