1
|
Brodie C. Simple software solution for N 2 diversion when measuring δ 18O values of nitrogen-rich samples materials using a Thermo Scientific EA-IRMS System. MethodsX 2023; 11:102268. [PMID: 38098775 PMCID: PMC10719525 DOI: 10.1016/j.mex.2023.102268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 06/02/2023] [Indexed: 12/17/2023] Open
Abstract
This method is a simple, cost-free, and reliable approach for the removal of N2 interference on a CO analyte when analysing nitrogen-rich (>0.5% w/w) samples by Elemental Analysis Isotope Ratio Mass Spectrometry. Specifically, the isobaric interference on m/z 30 is eliminated using only the open split of the Thermo Scientific ConFlo IV Universal Interface Device, improving the analytical workflow when using a static temperature Gas Chromatography (GC) column. It simplifies the N2 diversion methods described in recent decades. When applied, the method described here:•Provides sufficient baseline resolution between the N2 and CO analytes, to permit quantitative N2 diversion, using an extended length packed GC column;•Quantitatively eliminates all N2 analyte from the analytical gas stream ensuring that no N2 enters the ion source and therefore no isobaric interference is produced on m/z 30 ion trace of the CO analyte;•Allows reproducible measurement of δ18O values from nitrogen-rich sample materials without a N2 isobaric interference, where the CO analyte is measured on the analytical baseline that it was produced on in the reactor (i.e., no addition make-up helium or new baseline of pure helium for the CO analyte).
Collapse
Affiliation(s)
- Christopher Brodie
- Isotrace New Zealand Limited, 167 High Street, Dunedin, 9016, New Zealand
| |
Collapse
|
2
|
Koehler G, Hobson KA. Delineating origins of cheetah cubs in the illegal wildlife trade: Improvements based on the use of hair δ18O measurements. Front Ecol Evol 2023. [DOI: 10.3389/fevo.2023.1058985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Abstract
All African felids are listed as vulnerable or endangered according to the IUCN (International Union for Conservation of Nature) Red List of Threatened Species. Cheetahs (Acinonyx jubatus) in particular have declined rapidly as a result of human impacts so that development of effective strategies and tools for conservation of this highly vulnerable species, as well as African felids in general, are essential for their survival in the wild. Here we use the oxygen stable isotopic compositions of cheetah hair to determine origins of cheetah cubs destined for the illegal exotic pet trade by associating individual cubs with predicted δ18O isoscape locations. We found that cheetah cubs most likely originated in East Africa, close to the corridors responsible for this aspect of the illegal wildlife trade to the Middle East. Further refinement of these assignments using a two isotope analysis (δ18O and δ13C values) indicate that these cubs were likely sourced in Southern Ethiopia or possibly as far as Tanzania. We also demonstrate that δ18O values in tissues can provide provenance information in cases where results of δ2H analyses may be obscured by the effects of metabolic routing of nutrients during nursing, starvation, or dehydration. This study demonstrates the utility of stable isotopic tools for conservation and forensic uses for endangered mammalian species.
Collapse
|
3
|
Magozzi S, Bataille CP, Hobson KA, Wunder MB, Howa JD, Contina A, Vander Zanden HB, Bowen GJ. Calibration chain transformation improves the comparability of organic hydrogen and oxygen stable isotope data. Methods Ecol Evol 2021. [DOI: 10.1111/2041-210x.13556] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sarah Magozzi
- Department of Geology and Geophysics University of Utah Salt Lake City UT USA
- Department of Integrative Marine Ecology Stazione Zoologica Anton DohrnFano Marine Centre Fano (PU) Italy
| | - Clement P. Bataille
- Department of Earth and Environmental Sciences University of Ottawa Ottawa ON Canada
| | - Keith A. Hobson
- Department of Biology and Environment and Climate Change Canada Western University London ON Canada
| | - Michael B. Wunder
- Department of Integrative Biology University of Colorado Denver Denver CO USA
| | - John D. Howa
- Howa Analysis and Consulting LLC Salt Lake City UT USA
| | - Andrea Contina
- Department of Integrative Biology University of Colorado Denver Denver CO USA
| | | | - Gabriel J. Bowen
- Department of Geology and Geophysics University of Utah Salt Lake City UT USA
| |
Collapse
|
4
|
Magozzi S, Vander Zanden HB, Wunder MB, Trueman CN, Pinney K, Peers D, Dennison PE, Horns JJ, Şekercioğlu ÇH, Bowen GJ. Combining Models of Environment, Behavior, and Physiology to Predict Tissue Hydrogen and Oxygen Isotope Variance Among Individual Terrestrial Animals. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.536109] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Variations in stable hydrogen and oxygen isotope ratios in terrestrial animal tissues are used to reconstruct origin and movement. An underlying assumption of these applications is that tissues grown at the same site share a similar isotopic signal, representative of the location of their origin. However, large variations in tissue isotopic compositions often exist even among conspecific individuals within local populations, which complicates origin and migration inferences. Field-data and correlation analyses have provided hints about the underlying mechanisms of within-site among-individual isotopic variance, but a theory explaining the causes and magnitude of such variance has not been established. Here we develop a mechanistic modeling framework that provides explicit predictions of the magnitude, patterns, and drivers of isotopic variation among individuals living in a common but environmentally heterogeneous habitat. The model toolbox includes isoscape models of environmental isotopic variability, an agent-based model of behavior and movement, and a physiology-biochemistry model of isotopic incorporation into tissues. We compare model predictions against observed variation in hatch-year individuals of the songbird Spotted Towhee (Pipilo maculatus) in Red Butte Canyon, Utah, and evaluate the ability of the model to reproduce this variation under different sets of assumptions. Only models that account for environmental isotopic variability predict a similar magnitude of isotopic variation as observed. Within the modeling framework, behavioral rules and properties govern how animals nesting in different locations acquire resources from different habitats, and birds nesting in or near riparian habitat preferentially access isotopically lighter resources than those associated with the meadow and slope habitats, which results in more negative body water and tissue isotope values. Riparian nesters also have faster body water turnover and acquire more water from drinking (vs. from food), which exerts a secondary influence on their isotope ratios. Thus, the model predicts that local among-individual isotopic variance is linked first to isotopic heterogeneity in the local habitat, and second to how animals sample this habitat during foraging. Model predictions provide insight into the fundamental mechanisms of small-scale isotopic variance and can be used to predict the utility of isotope-based methods for specific groups or environments in ecological and forensic research.
Collapse
|
5
|
Wang C, Wallace AF, Heraty L, Qi H, Sturchio NC. Alkaline hydrolysis pathway of 2,4-dinitroanisole verified by 18O tracer experiment. JOURNAL OF HAZARDOUS MATERIALS 2020; 396:122627. [PMID: 32305747 DOI: 10.1016/j.jhazmat.2020.122627] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 03/30/2020] [Accepted: 03/30/2020] [Indexed: 06/11/2023]
Abstract
The environmental fate of insensitive munitions compounds, such as 2,4-dinitroanisole (DNAN), has drawn increasing attention because of their growing use in military activities. One of the main attenuation mechanisms of DNAN degradation in aqueous environments is alkaline hydrolysis. We investigated the pathway for alkaline hydrolysis of DNAN at pH 12 by a combined approach of experiment and theory. An experiment using 18O-labeled water was performed to verify the reaction pathway. Calculated free energies for two putative reaction pathways by density-functional theory optimized at the SMD(Pauling)/M06-2X/6-311++G(2d,2p) level including explicit solvation of DNAN by 10 H2O molecules and one OH- ion gave a prediction in agreement with the experimental result. The verified reaction pathway for alkaline hydrolysis of DNAN is a SN2Ar nucleophilic aromatic substitution with a methoxy leaving group (OCH3) at the C1 site.
Collapse
Affiliation(s)
- Chunlei Wang
- Department of Earth Sciences, University of Delaware, Newark, DE, 19716, USA
| | - Adam F Wallace
- Department of Earth Sciences, University of Delaware, Newark, DE, 19716, USA
| | - Linnea Heraty
- Department of Earth Sciences, University of Delaware, Newark, DE, 19716, USA
| | - Haiping Qi
- Reston Stable Isotope Laboratory, U.S. Geological Survey, Reston, VA, 20192, USA
| | - Neil C Sturchio
- Department of Earth Sciences, University of Delaware, Newark, DE, 19716, USA.
| |
Collapse
|
6
|
Holder PW, Van Hale RJ, Frew R, George S, Armstrong KF. Natal origin of the invasive biosecurity pest, brown marmorated stink bug (Halyomorpha halys: Penatomidae), determined by dual-element stable isotope-ratio mass spectrometry. PEST MANAGEMENT SCIENCE 2020; 76:1456-1463. [PMID: 31659828 PMCID: PMC7065004 DOI: 10.1002/ps.5659] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 10/23/2019] [Accepted: 10/23/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND Post-border detection of a single brown marmorated stink bug (BMSB) in New Zealand warranted a biosecurity response, the nature of which would be influenced by its status as part of an established population or as a new arrival. Stable isotope analysis has the potential to determine natal origins, but is difficult to achieve for samples as small as a single insect. Here an analytical modification to measure small samples was successfully trialled as a means to supply evidence as to the local or exotic natal origin of the intercepted BMSB specimen. RESULTS Sufficient analytical sensitivity was achieved using a modified isotope ratio mass spectrometry method, involving thermolysis and carbon monoxide cryofocusing, to enable the simultaneous analysis of δ2 H and δ18 O from wings of the post-border BMSB sample. The values were much lower than those of the New Zealand green vegetable bug, used as a local reference. However, they fell within the range of those for BMSB of Northern Hemisphere origin intercepted at the New Zealand border over the same time period, specifically overlapping with the USA and Italy, but not China. CONCLUSION The isotope signature of the post-border detected BMSB suggested a significantly cooler climate than the North Island of New Zealand, indicating that it was a new arrival and did not represent an established population. © 2019 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Collapse
Affiliation(s)
- Peter W Holder
- Bio‐Protection Research CentreLincoln UniversityChristchurchNew Zealand
| | | | - Russell Frew
- Department of ChemistryUniversity of OtagoDunedinNew Zealand
| | - Sherly George
- Plant Health & Environment LaboratoryMinistry for Primary IndustriesAucklandNew Zealand
| | - Karen F Armstrong
- Bio‐Protection Research CentreLincoln UniversityChristchurchNew Zealand
| |
Collapse
|
7
|
Koehler G, Hobson KA. Tracking cats revisited: Placing terrestrial mammalian carnivores on δ2H and δ18O isoscapes. PLoS One 2019; 14:e0221876. [PMID: 31479471 PMCID: PMC6720029 DOI: 10.1371/journal.pone.0221876] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 08/14/2019] [Indexed: 11/19/2022] Open
Abstract
The relationship between hydrogen and oxygen stable isotopic compositions in environmental water and hair was investigated for both domestic cats (Felis catus) and dogs (Canis lupus familiaris). A strong, but different, covariance was measured between the hydrogen and oxygen stable isotopic compositions of local precipitation and hair keratin from both cats and dogs. These isotopic differences are most likely a result of the differences between the dietary and drinking water needs of cats compared to dogs. Moreover, the δ2H and δ18O values of hair from captive and wild felids and canids, such as cougars (Puma concolor), bobcats (Lynx rufus), and wolves (Canis lupus) are broadly consistent with these measurements. This evidence indicates that while the water budgets of terrestrial mammalian carnivores need to be considered in isotopic applications, it is clear that felids and canids may be placed on tissue–specific hydrogen and oxygen isotopic landscapes for ecological, provenance, or forensic studies.
Collapse
Affiliation(s)
- Geoff Koehler
- NHRC Stable Isotope Laboratory, Environment and Climate Change Canada, Saskatoon, SK, Canada
- * E-mail:
| | - Keith A. Hobson
- NHRC Stable Isotope Laboratory, Environment and Climate Change Canada, Saskatoon, SK, Canada
- Department of Biology, University of Western Ontario, London, ON, Canada
| |
Collapse
|
8
|
Geographical assignment of polar bears using multi-element isoscapes. Sci Rep 2019; 9:9390. [PMID: 31253845 PMCID: PMC6599000 DOI: 10.1038/s41598-019-45874-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 06/14/2019] [Indexed: 11/16/2022] Open
Abstract
Wide-ranging apex predators are among the most challenging of all fauna to conserve and manage. This is especially true of the polar bear (Ursus maritimus), an iconic predator that is hunted in Canada and threatened by global climate change. We used combinations of stable isotopes (13C,15N,2H,18O) in polar bear hair from > 1000 individuals, sampled from across much of the Canadian Arctic and sub-Arctic, to test the ability of stable isotopic profiles to ‘assign’ bears to (1) predefined managed subpopulations, (2) subpopulations defined by similarities in stable isotope values using quadratic discriminant analysis, and (3) spatially explicit, isotopically distinct clusters derived from interpolated (i.e. ‘kriged’) isotopic landscapes, or ‘isoscapes’, using the partitioning around medoids algorithm. A four-isotope solution provided the highest overall assignment accuracies (~80%) to pre-existing management subpopulations with accuracy rates ranging from ~30–99% (median = 64%). Assignment accuracies of bears to hierarchically clustered ecological groups based on isotopes ranged from ~64–99%. Multivariate assignment to isotopic clusters resulted in highest assignment accuracies of 68% (33–77%), 84% (47–96%) and 74% (53–85%) using two, three and four stable isotope groups, respectively. The resulting spatial structure inherent in the multiple stable isotopic compositions of polar bear tissues is a powerful forensic tool that will, in this case, contribute to the conservation and management of this species. Currently, it is unclear what is driving these robust isotopic patterns and future research is needed to evaluate the processes behind the pattern. Nonetheless, our isotopic approach can be further applied to other apex mammalian predators under threat, such as the large felids, providing that isotopic structure occurs throughout their range.
Collapse
|
9
|
Effects of tanning on the stable isotopic compositions of hair. Forensic Sci Int 2018; 292:78-82. [DOI: 10.1016/j.forsciint.2018.08.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 08/16/2018] [Accepted: 08/20/2018] [Indexed: 11/20/2022]
|
10
|
Grimm BL, Stern LA, Lowe AJ. Forensic utility of a nitrogen and oxygen isotope ratio time series of ammonium nitrate and its isolated ions. Talanta 2018; 178:94-101. [DOI: 10.1016/j.talanta.2017.08.105] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 08/29/2017] [Accepted: 08/30/2017] [Indexed: 11/28/2022]
|
11
|
Camin F, Perini M, Bontempo L, Galeotti M, Tibaldi E, Piasentier E. Stable isotope ratios of H, C, O, N and S for the geographical traceability of Italian rainbow trout (Oncorhynchus mykiss). Food Chem 2017; 267:288-295. [PMID: 29934170 DOI: 10.1016/j.foodchem.2017.06.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 05/22/2017] [Accepted: 06/05/2017] [Indexed: 11/28/2022]
Abstract
Multielement isotope ratio was assessed in fat and defatted (protein) fillet of 130 rainbow trout, reared with feed incorporating a high or low fish content in 20 Italian farms, focusing on two northern Italian regions (Friuli Venezia Giulia and Trentino). The aim was to investigate the ability of isotopic analysis to trace the geographical origin of trout, also according to the type of feed. The carbon, nitrogen and sulphur isotope ratios of feed and fillet were highly positively correlated both within each matrix (feed or fillet) and between the two matrices and negatively correlated with the δ2H and δ18O of feed and the δ2Hfat. The δ2Hprotein and δ18Oprotein were positively interrelated with the δ18O of tank water. By applying the tested Partial Least Squares - Discriminant Analysis multiclass model (85 fillets) to the validation dataset (45 fillets), 91% accuracy was obtained for the two Italian regions.
Collapse
Affiliation(s)
- Federica Camin
- Department of Food Quality and Nutrition, Research and Innovation Centre, Fondazione Edmund Mach (FEM), Via E. Mach 1, 38010 San Michele all'Adige, Italy; University of Udine, Department of Agriculture, Food, Environmental and Animal Sciences, via delle Scienze 206, 33100 Udine, Italy
| | - Matteo Perini
- Experiment and Technological Services Department, Technology Transfer Centre, Fondazione Edmund Mach (FEM), Via E. Mach 1, 38010 San Michele all'Adige, Italy.
| | - Luana Bontempo
- Department of Food Quality and Nutrition, Research and Innovation Centre, Fondazione Edmund Mach (FEM), Via E. Mach 1, 38010 San Michele all'Adige, Italy
| | - Marco Galeotti
- University of Udine, Department of Agriculture, Food, Environmental and Animal Sciences, via delle Scienze 206, 33100 Udine, Italy
| | - Emilio Tibaldi
- University of Udine, Department of Agriculture, Food, Environmental and Animal Sciences, via delle Scienze 206, 33100 Udine, Italy
| | - Edi Piasentier
- University of Udine, Department of Agriculture, Food, Environmental and Animal Sciences, via delle Scienze 206, 33100 Udine, Italy
| |
Collapse
|
12
|
Vander Zanden HB, Soto DX, Bowen GJ, Hobson KA. Expanding the Isotopic Toolbox: Applications of Hydrogen and Oxygen Stable Isotope Ratios to Food Web Studies. Front Ecol Evol 2016. [DOI: 10.3389/fevo.2016.00020] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
13
|
Chen ZG, Yin XJ, Zhou Y. Effects of GC temperature and carrier gas flow rate on on-line oxygen isotope measurement as studied by on-column CO injection. JOURNAL OF MASS SPECTROMETRY : JMS 2015; 50:1023-1030. [PMID: 28338273 DOI: 10.1002/jms.3617] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 05/08/2015] [Accepted: 05/16/2015] [Indexed: 06/06/2023]
Abstract
Although deemed important to δ18 O measurement by on-line high-temperature conversion techniques, how the GC conditions affect δ18 O measurement is rarely examined adequately. We therefore directly injected different volumes of CO or CO-N2 mix onto the GC column by a six-port valve and examined the CO yield, CO peak shape, CO-N2 separation, and δ18 O value under different GC temperatures and carrier gas flow rates. The results show the CO peak area decreases when the carrier gas flow rate increases. The GC temperature has no effect on peak area. The peak width increases with the increase of CO injection volume but decreases with the increase of GC temperature and carrier gas flow rate. The peak intensity increases with the increase of GC temperature and CO injection volume but decreases with the increase of carrier gas flow rate. The peak separation time between N2 and CO decreases with an increase of GC temperature and carrier gas flow rate. δ18 O value decreases with the increase of CO injection volume (when half m/z 28 intensity is <3 V) and GC temperature but is insensitive to carrier gas flow rate. On average, the δ18 O value of the injected CO is about 1‰ higher than that of identical reference CO. The δ18 O distribution pattern of the injected CO is probably a combined result of ion source nonlinearity and preferential loss of C16 O or oxygen isotopic exchange between zeolite and CO. For practical application, a lower carrier gas flow rate is therefore recommended as it has the combined advantages of higher CO yield, better N2 -CO separation, lower He consumption, and insignificant effect on δ18 O value, while a higher-than-60 °C GC temperature and a larger-than-100 µl CO volume is also recommended. When no N2 peak is expected, a higher GC temperature is recommended, and vice versa. Copyright © 2015 John Wiley & Sons, Ltd.
Collapse
Affiliation(s)
- Zhi-Gang Chen
- College of Ocean and Earth Sciences, Xiamen University, Xiamen, 361102, China
- Key Laboratory of Coastal and Wetland Ecosystems, Ministry of Education, Xiamen University, Xiamen, 361102, China
| | - Xi-Jie Yin
- The Third Institute of Oceanography, State Oceanic Administration, Xiamen, 361005, China
| | - Youping Zhou
- Institute for Landscape Biogeochemistry, ZALF, Müncheberg, Germany
- Leibniz Institute of Freshwater Ecology and Inland Fisheries, Neuglobsow, Germany
| |
Collapse
|
14
|
Soto DX, Koehler G, Hobson KA. Combining Denitrifying Bacteria and Laser Spectroscopy for Isotopic Analyses (δ15N, δ18O) of Dissolved Nitrate. Anal Chem 2015; 87:7000-5. [DOI: 10.1021/acs.analchem.5b01119] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- David X. Soto
- Environment
Canada, 11 Innovation Boulevard, Saskatoon, Saskatchewan, Canada, S7N 3H5
| | - Geoff Koehler
- Environment
Canada, 11 Innovation Boulevard, Saskatoon, Saskatchewan, Canada, S7N 3H5
| | - Keith A. Hobson
- Environment
Canada, 11 Innovation Boulevard, Saskatoon, Saskatchewan, Canada, S7N 3H5
| |
Collapse
|
15
|
Li WB, Song YB, Xu HK, Chen LY, Dai WH, Dong M. Ion-exchange method in the collection of nitrate from freshwater ecosystems for nitrogen and oxygen isotope analysis: a review. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015; 22:9575-9588. [PMID: 25940469 DOI: 10.1007/s11356-015-4522-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 04/09/2015] [Indexed: 06/04/2023]
Abstract
Nitrate (NO3(-)) contamination of freshwater is considered one of the most prevalent global environmental problems. Dual stable isotopic compositions (δ(15)N and δ(18)O) of NO3(-) can provide helpful information and have been well documented as being a powerful tool to track the source of NO3(-) in freshwater ecosystems. The ion-exchange method is a reliable and precise technique for measuring the δ(15)N and δ(18)O of NO3(-) and has been widely employed to collect NO3(-) from freshwater ecosystems. This review summarizes and presents the principles, affecting factors and corresponding significant improvements of the ion-exchange method. Finally, potential improvements and perspectives for the applicability of this method are also discussed, as are suggestions for further research and development drawn from the overall conclusions.
Collapse
Affiliation(s)
- Wen-Bing Li
- Key Laboratory of Hangzhou City for Ecosystem Protection and Restoration, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, 310036, China
| | | | | | | | | | | |
Collapse
|
16
|
Wassenaar LI, Hobson KA, Sisti L. An online temperature-controlled vacuum-equilibration preparation system for the measurement of δ2H values of non-exchangeable-H and of δ18O values in organic materials by isotope-ratio mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2015; 29:397-407. [PMID: 26349461 DOI: 10.1002/rcm.7118] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 12/05/2014] [Accepted: 12/06/2014] [Indexed: 06/05/2023]
Abstract
RATIONALE Measurement of δ(2) H values in non-exchangeable-H (δ(2) H(n)) and δ(18)O values in organic environmental samples are inconsistent among laboratories worldwide due to varied and lengthy approaches in controlling for H isotope exchange (for δ(2)H(n) values) and removal of trace moisture (δ(2)H(n) and δ(18)O values), which undermines the comparability of organic δ(2)H and δ(18)O data produced among different laboratories. METHODS An online preparation system was developed for the measurement of the δ(2)H(n) and δ(18)O values of organic samples, coupled to isotope-ratio mass spectrometers. The system features a 50-position autosampler and isolation valve where (1) the samples are held isothermal between ambient to 40-120 ± 0.1 °C for H isotopic exchange experiments (δ(2) H(n)) and drying of hygroscopic samples (δ(2) H(n) and δ(18)O), (2) the samples are evacuated to <5 mbar and flushed with helium for moisture and N(2) removal, and (3) injection of up to 500 μL of H(2)O is possible for controlled vapour exchangeable-H experiments. RESULTS The system provides highly reproducible and precise δ(2)H(n) isotope estimates for a range of organic keratinous standard powders over a wide range of experimental temperatures. A reproducible sample processing regimen can now be applied to a wider range of organics and hygroscopic samples that are currently hampered by poorly controlled preparative methods amongst laboratories. CONCLUSIONS Rapid and reproducible online vacuum equilibration of samples and standards for the routine measurement of δ(2)H(n) and δ(18)O values is now possible using the online equilibration system, with the added benefit that sample processing times for organic δ(2)H values are reduced from weeks to hours.
Collapse
Affiliation(s)
| | - Keith A Hobson
- Environment Canada, 11 Innovation Blvd., Saskatoon, SK, Canada, S7N 3H5
| | | |
Collapse
|
17
|
Pekarsky S, Angert A, Haese B, Werner M, Hobson KA, Nathan R. Enriching the isotopic toolbox for migratory connectivity analysis: a new approach for migratory species breeding in remote or unexplored areas. DIVERS DISTRIB 2015. [DOI: 10.1111/ddi.12306] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Affiliation(s)
- Sasha Pekarsky
- Movement Ecology Lab Dept. of Ecology Evolution & Behavior; Alexander Silberman Institute of Life Sciences; The Hebrew University of Jerusalem; Jerusalem 91904 Israel
| | - Alon Angert
- The Institute of Earth Sciences; The Hebrew University of Jerusalem; Jerusalem 91904 Israel
| | - Barbara Haese
- Alfred Wegener Institute for Polar and Marine Research (AWI); Bussestr. 24 Bremerhaven 27570 Germany
| | - Martin Werner
- Alfred Wegener Institute for Polar and Marine Research (AWI); Bussestr. 24 Bremerhaven 27570 Germany
| | - Keith A. Hobson
- Environment Canada; 11 Innovation Blvd Saskatoon SK Canada S7N 3H5
| | - Ran Nathan
- Movement Ecology Lab Dept. of Ecology Evolution & Behavior; Alexander Silberman Institute of Life Sciences; The Hebrew University of Jerusalem; Jerusalem 91904 Israel
| |
Collapse
|
18
|
Hobson KA, Koehler G. On the use of stable oxygen isotope (δ (18)O) measurements for tracking avian movements in North America. Ecol Evol 2015; 5:799-806. [PMID: 25691999 PMCID: PMC4328780 DOI: 10.1002/ece3.1383] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 12/06/2014] [Accepted: 12/12/2014] [Indexed: 11/05/2022] Open
Abstract
Tracking migratory animals has benefitted using measurements of naturally occurring stable isotopes of hydrogen (δ (2)H) in keratinous tissues such as hair and feathers to link animal origins to continental patterns or isoscapes of δ (2)H in precipitation. However, for most taxa, much less information exists on the use of stable oxygen isotope ratios (δ (18)O) despite the fact that δ (2)H and δ (18)O are strongly linked in environmental waters through the meteoric relationship and the possibility of using both isotopes to infer greater information on origins and climatic conditions where tissues are grown. A fundamental requirement of using stable isotopes to assign individuals and populations to origins is the development of a rescaling function linking environmental food web signals to the tissue of interest and for birds, this has not been carried out. Here, we derived the relationship between H and O isotopes in known source feathers of 104 individuals representing 11 species of insectivorous passerines sampled across the strong precipitation isoscape of North America. We determined again a strong expected relationship between feather δ (2)H (δ (2)Hf) and long-term amount-weighted precipitation δ (2)H (δ (2)Hp; r (2) = 0.77), but the corresponding relationship between δ (18)Of and δ (18)Op was poor (r (2) = 0.32) for the same samples. This suggests that δ (2)H measurements are currently more useful for assignment of insectivorous songbirds to precipitation isoscapes but does not preclude other uses of the δ (18)Of data. Currently, mechanisms responsible for the decoupling of H and O isotopes in food webs is poorly known, and we advocate a much broader sampling of both isotopes in the same keratinous tissues across precipitation isotope gradients and across taxa to resolve this issue and to increase the power of using water isotopes to track migratory animals.
Collapse
Affiliation(s)
- Keith A Hobson
- Environment Canada 11 Innovation Blvd., Saskatoon, Saskatchewan, Canada, S7N 3H5
| | - Geoff Koehler
- Environment Canada 11 Innovation Blvd., Saskatoon, Saskatchewan, Canada, S7N 3H5
| |
Collapse
|
19
|
Brust H, Koeberg M, van der Heijden A, Wiarda W, Mügler I, Schrader M, Vivo-Truyols G, Schoenmakers P, van Asten A. Isotopic and elemental profiling of ammonium nitrate in forensic explosives investigations. Forensic Sci Int 2014; 248:101-12. [PMID: 25602642 DOI: 10.1016/j.forsciint.2014.11.024] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 11/22/2014] [Accepted: 11/27/2014] [Indexed: 11/26/2022]
Abstract
Ammonium nitrate (AN) is frequently encountered in explosives in forensic casework. It is widely available as fertilizer and easy to implement in explosive devices, for example by mixing it with a fuel. Forensic profiling methods to determine whether material found on a crime scene and material retrieved from a suspect arise from the same source are becoming increasingly important. In this work, we have explored the possibility of using isotopic and elemental profiling to discriminate between different batches of AN. Variations within a production batch, between different batches from the same manufacturer, and between batches from different manufacturers were studied using a total of 103 samples from 19 different fertilizer manufacturers. Isotope-ratio mass spectrometry (IRMS) was used to analyze AN samples for their (15)N and (18)O isotopic composition. The trace-elemental composition of these samples was studied using inductively coupled plasma-mass spectrometry (ICP-MS). All samples were analyzed for the occurrence of 66 elements. 32 of these elements were useful for the differentiation of AN samples. These include magnesium (Mg), calcium (Ca), iron (Fe) and strontium (Sr). Samples with a similar elemental profile may be differentiated based on their isotopic composition. Linear discriminant analysis (LDA) was used to calculate likelihood ratios and demonstrated the power of combining elemental and isotopic profiling for discrimination between different sources of AN.
Collapse
Affiliation(s)
- Hanneke Brust
- University of Amsterdam, van 't Hoff Institute for Molecular Sciences, PO Box 94157, 1090 GD Amsterdam, The Netherlands; Netherlands Forensic Institute, PO Box 24044, 2490 AA The Hague, The Netherlands; TNO Defence, Security and Safety, PO Box 45, 2280 AA Rijswijk, The Netherlands.
| | - Mattijs Koeberg
- Netherlands Forensic Institute, PO Box 24044, 2490 AA The Hague, The Netherlands.
| | - Antoine van der Heijden
- TNO Defence, Security and Safety, PO Box 45, 2280 AA Rijswijk, The Netherlands; Delft University of Technology, PO Box 5, 2600 AA Delft, The Netherlands.
| | - Wim Wiarda
- Netherlands Forensic Institute, PO Box 24044, 2490 AA The Hague, The Netherlands.
| | - Ines Mügler
- Netherlands Forensic Institute, PO Box 24044, 2490 AA The Hague, The Netherlands
| | - Marianne Schrader
- Netherlands Forensic Institute, PO Box 24044, 2490 AA The Hague, The Netherlands.
| | - Gabriel Vivo-Truyols
- University of Amsterdam, van 't Hoff Institute for Molecular Sciences, PO Box 94157, 1090 GD Amsterdam, The Netherlands.
| | - Peter Schoenmakers
- University of Amsterdam, van 't Hoff Institute for Molecular Sciences, PO Box 94157, 1090 GD Amsterdam, The Netherlands.
| | - Arian van Asten
- University of Amsterdam, van 't Hoff Institute for Molecular Sciences, PO Box 94157, 1090 GD Amsterdam, The Netherlands; Netherlands Forensic Institute, PO Box 24044, 2490 AA The Hague, The Netherlands; CLHC, Amsterdam Center for Forensic Science and Medicine, PO Box 94157, 1090 GD Amsterdam, The Netherlands.
| |
Collapse
|
20
|
Bontempo L, Ceppa F, Ziller L, Pedrini P, Hobson KA, Wassenaar LI, Camin F. Comparison of methods for stable isotope ratio (δ13C, δ15N, δ2H, δ18O) measurements of feathers. Methods Ecol Evol 2014. [DOI: 10.1111/2041-210x.12165] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Luana Bontempo
- Department of Food Quality and Nutrition; Research and Innovation Centre; Fondazione Edmund Mach (FEM); Via E. Mach 1 38010 San Michele all'Adige Italy
| | - Florencia Ceppa
- Department of Food Quality and Nutrition; Research and Innovation Centre; Fondazione Edmund Mach (FEM); Via E. Mach 1 38010 San Michele all'Adige Italy
| | - Luca Ziller
- Department of Food Quality and Nutrition; Research and Innovation Centre; Fondazione Edmund Mach (FEM); Via E. Mach 1 38010 San Michele all'Adige Italy
| | - Paolo Pedrini
- MUSE - Museo delle Scienze; Sezione Zoologia dei Vertebrati, Corso del Lavoro e della Scienza 3 - 38123 Trento Italy
| | - Keith A. Hobson
- Environment Canada Wildlife Research; West, 11 Innovation Blvd Saskatoon SK S7N 3H5 Canada
| | - Leonard I. Wassenaar
- Isotope Hydrology Laboratory; IAEA - International Atomic Energy Agency; Vienna International Centre; PO Box 100 1400 Vienna Austria
| | - Federica Camin
- Department of Food Quality and Nutrition; Research and Innovation Centre; Fondazione Edmund Mach (FEM); Via E. Mach 1 38010 San Michele all'Adige Italy
| |
Collapse
|
21
|
Isshiki M, Nakamura S, Takashima Y, Terada S, Suzuki Y. Determination of the Geographic Origin of Eel Products by Stable Isotope Ratio Analysis. J JPN SOC FOOD SCI 2014. [DOI: 10.3136/nskkk.61.54] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
22
|
von Holstein ICC, Hamilton J, Craig OE, Newton J, Collins MJ. Comparison of isotopic variability in proteinaceous tissues of a domesticated herbivore: a baseline for zooarchaeological investigation. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2013; 27:2601-15. [PMID: 24591021 DOI: 10.1002/rcm.6725] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 08/27/2013] [Accepted: 08/28/2013] [Indexed: 05/23/2023]
Abstract
RATIONALE A variety of metabolic, dietary and climatic influences on isotopic variation have been established in mammalian hair. The relevance of these factors to collagen isotopic composition is unknown, but would be of great interest to zooarchaeological analyses of faunal skeletal tissue. METHODS The relationships between carbon (δ(13)C), nitrogen (δ(15)N), non-exchangeable hydrogen (δ(2)H) and oxygen (δ(18)O) values of defatted, demineralised and gelatinised bone collagen and defatted wool keratin from two sheep flocks (n = 20, 5) in the UK were investigated, including testing for the effects of nutritional plane, sex, pregnancy and season of sample collection. The sulfur composition (δ(34)S values) was also investigated for tissues from the smaller flock. RESULTS Bulk collagen was enriched in (13)C over bulk keratin by 2.0 - 2.7‰ and in (2)H by 29 - 40‰ but depleted in (18)O relative to keratin by 1.8‰. Differences in δ(15)N values were within experimental error. The collagen samples were generally more enriched in (34)S than keratin, but this was very variable. Pregnancy, sex and season, but not nutritional plane, significantly affected isotope values but did not change overall keratin-collagen relationships. CONCLUSIONS This dataset provides a baseline measure of variability and comparability for isotopic investigations into origin and husbandry conditions in archaeological sheep tissues, both collagen and keratin.
Collapse
Affiliation(s)
- I C C von Holstein
- BioArCh, Departments of Archaeology and Chemistry, University of York, Heslington, York, YO10 5DD, UK
| | | | | | | | | |
Collapse
|
23
|
Hunsinger GB, Tipple CA, Stern LA. Gaseous byproducts from high-temperature thermal conversion elemental analysis of nitrogen- and sulfur-bearing compounds with considerations for δ2H and δ18O analyses. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2013; 27:1649-1659. [PMID: 23754799 DOI: 10.1002/rcm.6608] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 04/23/2013] [Accepted: 04/24/2013] [Indexed: 06/02/2023]
Abstract
RATIONALE High-temperature, conversion-reduction (HTC) systems convert hydrogen and oxygen in materials into H2 and CO for δ(2)H and δ(18)O measurements by isotope ratio mass spectrometry. HTC of nitrogen- and sulfur-bearing materials produces unintended byproduct gases that could affect isotope analyses by: (1) allowing isotope exchange reactions downstream of the HTC reactor, (2) creating isobaric or co-elution interferences, and (3) causing deterioration of the chromatography. This study characterizes these HTC byproducts. METHODS A HTC system (ThermoFinnigan TC/EA) was directly connected to a gas chromatograph/quadrupole mass spectrometer in scan mode (m/z 8 to 88) to identify the volatile products generated by HTC at conversion temperatures of 1350 °C and 1450 °C for a range of nitrogen- and sulfur-bearing solids [keratin powder, horse hair, caffeine, ammonium nitrate, potassium nitrate, ammonium sulfate, urea, and three nitrated organic explosives (PETN, RDX, and TNT)]. RESULTS The prominent HTC byproduct gases include carbon dioxide, hydrogen cyanide, methane, acetylene, and water for all nitrogen-bearing compounds, as well as carbon disulfide, carbonyl sulfide, and hydrogen sulfide for sulfur-bearing compounds. The 1450 °C reactor temperature reduced the abundance of most byproduct gases, but increased the significant byproduct, hydrogen cyanide. Inclusion of a post-reactor chemical trap containing Ascarite II and Sicapent, in series, eliminated the majority of byproducts. CONCLUSIONS This study identified numerous gaseous HTC byproducts. The potential adverse effects of these gases on isotope ratio analyses are unknown but may be mitigated by higher HTC reactor temperatures and purifying the products with a purge-and-trap system or with chemical traps.
Collapse
Affiliation(s)
- Glendon B Hunsinger
- Counterterrorism and Forensic Science Research Unit, FBI Laboratory, Quantico, VA 22135, USA
| | | | | |
Collapse
|
24
|
Soto DX, Wassenaar LI, Hobson KA. Stable hydrogen and oxygen isotopes in aquatic food webs are tracers of diet and provenance. Funct Ecol 2013. [DOI: 10.1111/1365-2435.12054] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- David X. Soto
- Environment Canada 11 Innovation Boulevard Saskatoon SK S7N 3H5 Canada
| | | | - Keith A. Hobson
- Environment Canada 11 Innovation Boulevard Saskatoon SK S7N 3H5 Canada
| |
Collapse
|
25
|
Ensuring the reliability of stable isotope ratio data—beyond the principle of identical treatment. Anal Bioanal Chem 2012; 405:2799-814. [DOI: 10.1007/s00216-012-6551-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2012] [Revised: 10/30/2012] [Accepted: 11/05/2012] [Indexed: 11/27/2022]
|
26
|
Skrzypek G. Normalization procedures and reference material selection in stable HCNOS isotope analyses: an overview. Anal Bioanal Chem 2012; 405:2815-23. [PMID: 23135627 DOI: 10.1007/s00216-012-6517-2] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 10/20/2012] [Accepted: 10/22/2012] [Indexed: 11/28/2022]
Abstract
The uncertainties of stable isotope results depend not only on the technical aspects of measurements, but also on how raw data are normalized to one of the international isotope scales. The inconsistency in the normalization methods used and in the selection of standards may lead to substantial differences in the results obtained. Therefore, unification of the data processing protocols employed is highly desirable. The best performing methods are two-point or multipoint normalization methods based on linear regression. Linear regression is most robust when based on standards that cover the entire range of δ values typically observed in nature, regardless of the δ values of the samples analysed. The uncertainty can be reduced by 50 % if measurements of two different standards are performed four times, or measurements of four standards are performed twice, with each batch of samples. Chemical matrix matching between standards and samples seems to be critical for δ (18)O of nitrate or δ (2)H of hair samples (thermal conversion/elemental analyser), for example; however, it is not necessarily always critical for all types of samples and techniques (e.g. not for most δ (15)N and δ (13)C elemental analyser analyses). To ensure that all published data can be recalculated, if δ values of standards or the isotope scales are to be updated, the details of the normalization technique and the δ values of the standards used should always be clearly reported.
Collapse
Affiliation(s)
- Grzegorz Skrzypek
- West Australian Biogeochemistry Centre, School of Plant Biology, The University of Western Australia, Crawley, WA, Australia.
| |
Collapse
|
27
|
Hagopian WM, Jahren AH. Elimination of nitrogen interference during online oxygen isotope analysis of nitrogen-doped organics using the "NiCat" nickel reduction system. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2012; 26:1776-1782. [PMID: 22777779 DOI: 10.1002/rcm.6285] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
RATIONALE Accurate online analysis of the δ(18)O values of nitrogen-bearing organic compounds is of interest to several emergent fields, including ecology, forensics and paleontology. During online analysis, high-temperature conversion (HTC) of nitrogen-bearing organics produces N(2) gas which creates isobaric interference with the isotopic measurement. Specifically, N(2) reacts with trace amounts of oxygen in the mass spectrometer source to form (14)N(16)O (m/z 30), which prevents accurate evaluation of the sample (12)C(18)O peak (m/z 30). METHODS We present an alternative system to the conventional HTC, which uses a nickel-catalyzed ("NiCat") reduction furnace to convert HTC-produced CO into CO(2), allowing for δ(18)O measurement using signal intensities at m/z 44 and 46. RESULTS This system yields identical δ(18)O values for nitrogen-doped and undoped sucrose and cellulose compounds up to molar yield ratios of N(2):CO = 0.22. In contrast, our conventional HTC system configured to factory recommendations with the stock gas chromatography (GC) column produced a discrepancy of ~5‰ between nitrogen-doped and undoped samples. CONCLUSIONS Because of its ability to eliminate isobaric interference, the NiCat system is a viable alternative to conventional HTC for δ(18)O measurement, and can be constructed from relatively inexpensive and readily available materials. As an additional advantage, the CO(2) analyte produced by NiCat may be cryofocused, to allow for oxygen-isotope determinations on very small amounts of sample substrate.
Collapse
Affiliation(s)
- William M Hagopian
- Department of Geology and Geophysics, University of Hawaii, Honolulu, HI 96822, USA.
| | | |
Collapse
|
28
|
Hobson KA, Soto DX, Paulson DR, Wassenaar LI, Matthews JH. A dragonfly (δ
2
H) isoscape for North America: a new tool for determining natal origins of migratory aquatic emergent insects. Methods Ecol Evol 2012. [DOI: 10.1111/j.2041-210x.2012.00202.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
29
|
Hunsinger GB, Stern LA. Improved accuracy in high-temperature conversion elemental analyzer δ18O measurements of nitrogen-rich organics. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2012; 26:554-562. [PMID: 22302495 DOI: 10.1002/rcm.6132] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
RATIONALE The use of high-temperature conversion (HTC) reduction systems interfaced with isotope ratio mass spectrometers for δ(18)O measurements of nitrogen-containing organic materials is complicated by isobaric interference from (14)N(16)O(+). This ion is produced in the ion source when N(2) reacts with trace oxygen shifting the m/z 30 baseline prior to elution of CO. METHODS We compared adaptations to a typical HTC system (TC/EA) to determine the best method to measure the δ(18)O values of nitrogen-rich organic substrates including: (1) 0.6 and 1.5 m 5 Å molecular sieve GC columns; (2) reduction of N(2) peak via He dilution; and (3) diversion of N(2) to waste via an automated four-port valve. These methods were applied to caffeine (IAEA-600), glycine, 4-nitroacetanilide, pentaerythritol tetranitrate (PETN) and cyclotrimethylene trinitramine (RDX), as well as pure and sodium azide-doped benzoic acid (IAEA-601) and sucrose (IAEA-CH6). RESULTS The efficiency of N(2) production in the HTC interface was highly variable among these compounds. Both the longer column and the dilutor improved, but did not eliminate, the adverse effects of nitrogen. CONCLUSIONS The diversion of N(2) adequately addressed the nitrogen-induced problems as indicated by: (1) consistent m/z 30 background offset between reference and sample CO for both N-free and N-rich materials; (2) production of the highest δ(18)O values; and (3) high correlation between the increase in the δ(18)O values relative to the GC-only measurements and the N(2) peak area. Additional validation would require N-rich oxygen isotope standards for inter-laboratory comparisons. Further, more stringent methodology may improve the poor inter-laboratory δ(18)O reproducibility of IAEA-600.
Collapse
Affiliation(s)
- Glendon B Hunsinger
- Counterterrorism and Forensic Science Research Unit, FBI Laboratory, Quantico, VA 22135, USA
| | | |
Collapse
|
30
|
Coplen TB, Qi H. USGS42 and USGS43: human-hair stable hydrogen and oxygen isotopic reference materials and analytical methods for forensic science and implications for published measurement results. Forensic Sci Int 2012; 214:135-41. [PMID: 21852055 DOI: 10.1016/j.forsciint.2011.07.035] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Revised: 07/06/2011] [Accepted: 07/17/2011] [Indexed: 10/17/2022]
Abstract
Because there are no internationally distributed stable hydrogen and oxygen isotopic reference materials of human hair, the U.S. Geological Survey (USGS) has prepared two such materials, USGS42 and USGS43. These reference materials span values commonly encountered in human hair stable isotope analysis and are isotopically homogeneous at sample sizes larger than 0.2 mg. USGS42 and USGS43 human-hair isotopic reference materials are intended for calibration of δ(2)H and δ(18)O measurements of unknown human hair by quantifying (1) drift with time, (2) mass-dependent isotopic fractionation, and (3) isotope-ratio-scale contraction. While they are intended for measurements of the stable isotopes of hydrogen and oxygen, they also are suitable for measurements of the stable isotopes of carbon, nitrogen, and sulfur in human and mammalian hair. Preliminary isotopic compositions of the non-exchangeable fractions of these materials are USGS42(Tibetan hair)δ(2)H(VSMOW-SLAP) = -78.5 ± 2.3‰ (n = 62) and δ(18)O(VSMOW-SLAP) = +8.56 ± 0.10‰ (n = 18) USGS42(Indian hair)δ(2)H(VSMOW-SLAP) = -50.3 ± 2.8‰ (n = 64) and δ(18)O(VSMOW-SLAP) = +14.11 ± 0.10‰ (n = 18). Using recommended analytical protocols presented herein for δ(2)H(VSMOW-SLAP) and δ(18)O(VSMOW-SLAP) measurements, the least squares fit regression of 11 human hair reference materials is δ(2)H(VSMOW-SLAP) = 6.085δ(2)O(VSMOW-SLAP) - 136.0‰ with an R-square value of 0.95. The δ(2)H difference between the calibrated results of human hair in this investigation and a commonly accepted human-hair relationship is a remarkable 34‰. It is critical that readers pay attention to the δ(2)H(VSMOW-SLAP) and δ(18)O(VSMOW-SLAP) of isotopic reference materials in publications, and they need to adjust the δ(2)H(VSMOW-SLAP) and δ(18)O(VSMOW-SLAP) measurement results of human hair in previous publications, as needed, to ensure all results on are on the same scales.
Collapse
Affiliation(s)
- Tyler B Coplen
- US Geological Survey, 431 National Center, Reston, VA 20192, USA.
| | | |
Collapse
|