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Steele ZT, Caceres K, Jameson AD, Griego M, Rogers EJ, Whiteman JP. A protocol for distilling animal body water from biological samples and measuring oxygen and hydrogen stable isotopes via cavity ring-down spectroscopy. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2024; 60:229-250. [PMID: 38472130 DOI: 10.1080/10256016.2024.2323201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 02/01/2024] [Indexed: 03/14/2024]
Abstract
The application of stable isotope analysis (SIA) to the fields of ecology and animal biology has rapidly expanded over the past three decades, particularly with regards to water analysis. SIA now provides the opportunity to monitor migration patterns, examine food webs, and assess habitat changes in current and past study systems. While carbon and nitrogen SIA of biological samples have become common, analyses of oxygen or hydrogen are used more sparingly despite their promising utility for tracing water sources and animal metabolism. Common ecological applications of oxygen or hydrogen SIA require injecting enriched isotope tracers. As such, methods for processing and analyzing biological samples are tailored for enriched tracer techniques, which require lower precision than other techniques given the large signal-to-noise ratio of the data. However, instrumentation advancements are creating new opportunities to expand the applications of high-throughput oxygen and hydrogen SIA. To support these applications, we update methods to distill and measure water derived from biological samples with consistent precision equal to, or better than, ± 0.1 ‰ for δ17O, ± 0.3 ‰ for δ18O, ± 1 ‰ for δ2H, ± 2 ‰ for d-excess, and ± 15 per meg for Δ17O.
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Affiliation(s)
- Zachary T Steele
- Department of Biological Sciences, Old Dominion University, Norfolk, VA, USA
| | - Karen Caceres
- Department of Biological Sciences, Old Dominion University, Norfolk, VA, USA
| | - Austin D Jameson
- Department of Biological Sciences, Old Dominion University, Norfolk, VA, USA
| | - Michael Griego
- Department of Biological Sciences, Old Dominion University, Norfolk, VA, USA
| | - Elizabeth J Rogers
- Organismic & Evolutionary Biology Program, University of Massachusetts, Amherst, MA, USA
| | - John P Whiteman
- Department of Biological Sciences, Old Dominion University, Norfolk, VA, USA
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Keinan J, Goldsmith Y. A simple method for rapid removal of the memory effect in cavity ring-down spectroscopy water isotope measurements. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2023; 37:e9600. [PMID: 37698151 DOI: 10.1002/rcm.9600] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 06/09/2023] [Accepted: 06/22/2023] [Indexed: 09/13/2023]
Abstract
RATIONALE The accuracy determined in the routine analysis of water isotopes (δ17 O, δ18 O, δ2 H) using cavity ring-down spectroscopy is greatly affected by the memory effect (ME), a sample-to-sample carryover that biases measurements. This study aims to develop a simple method that rapidly removes the ME. METHODS We developed a method, designed for the Picarro L2140-i, that removes the ME by injecting small amounts of water with an extreme isotopic value ("kick") in the opposite direction of the ME. We conducted 11 experiments to identify the optimal kick for pairs of isotopically enriched and depleted samples. Once quantified, the optimal kick was used to create an ME-free, unbiased calibration curve, which was verified using international and internal lab standards. RESULTS Our kick method removes the ME very efficiently in half the time it takes for experiments without a kick. The optimal number of kick injections required to minimize stabilization time between standards of different compositions is three injections of δ2 H ≈ -1000‰ water per a 100‰ difference between standards. Three runs of routine measurements using the kick method resulted in uncertainties of 0.03‰, 0.2‰, and 5 permeg for δ18 O, δ2 H, and 17 O-excess, respectively. CONCLUSIONS This study demonstrates a new method for rapidly removing the ME. Our kick protocol is a readily available, cheap, and efficient approach to reduce instrumental bias and improve measurement accuracy.
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Affiliation(s)
- Jonathan Keinan
- Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
- Geological Survey of Israel, Jerusalem, Israel
| | - Yonaton Goldsmith
- Institute of Earth Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
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Terzer-Wassmuth S, Wassenaar LI, Araguás-Araguás LJ, Stumpp C. Balancing precision and throughput of ..17O and .÷...17O analysis of natural waters by Cavity Ringdown Spectroscopy. MethodsX 2023; 10:102150. [PMID: 37091953 PMCID: PMC10113836 DOI: 10.1016/j.mex.2023.102150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 03/21/2023] [Indexed: 03/31/2023] Open
Abstract
δ 17O and Δ'17O are emerging tracers increasingly used in isotope hydrology, climatology, and biochemistry. Differentiating small relative abundance changes in the rare 17O isotope from the strong covariance with 18O imposes ultra-high precision requirements for this isotope analysis. Measurements of δ 17O by Cavity Ringdown Spectroscopy (CRDS) are attractive due to the ease of sample preparation, automated throughput, and avoidance of chemical conversions needed for isotope-ratio mass spectrometry. However, the CRDS approach requires trade-offs in measurement precision and uncertainty. In this protocol document, we present the following:•New analytical procedures and a software tool for conducting δ 17O and Δ'17O measurements by CRDS.•Outline a robust uncertainty framework for Δ'17O determinations.•Description of a CRDS performance framework for optimizing throughput, instrumental stability, and Δ'17O measurement precision and accuracy.
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Affiliation(s)
- Stefan Terzer-Wassmuth
- International Atomic Energy Agency, Department of Nuclear Sciences and Applications, Division of Physical and Chemical Sciences, Isotope Hydrology Section; Vienna International Centre, PO Box 100, A-1400 Vienna, Austria
- Corresponding author.
| | - Leonard I. Wassenaar
- International Atomic Energy Agency, Department of Nuclear Sciences and Applications, Division of Physical and Chemical Sciences, Isotope Hydrology Section; Vienna International Centre, PO Box 100, A-1400 Vienna, Austria
- Wassercluster Lunz Biological Research Station, Dr Carl Kupelwieser Promenade 5, A-3293 Lunz am See, Austria
| | - Luis J. Araguás-Araguás
- International Atomic Energy Agency, Department of Nuclear Sciences and Applications, Division of Physical and Chemical Sciences, Isotope Hydrology Section; Vienna International Centre, PO Box 100, A-1400 Vienna, Austria
| | - Christine Stumpp
- University of Natural Resources and Life Sciences, Department of Water, Atmosphere and Environment, Institute of Soil Physics and Rural Water Management; Muthgasse 18, A-1190 Vienna, Austria
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Voigt C, Vallet-Coulomb C, Piel C, Alexandre A. 17 O-excess and d-excess of atmospheric water vapor measured by cavity ring-down spectrometry: Evidence of a matrix effect and implication for the calibration procedure. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2022; 36:e9227. [PMID: 34845759 DOI: 10.1002/rcm.9227] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 11/22/2021] [Accepted: 11/22/2021] [Indexed: 06/13/2023]
Abstract
RATIONALE Producing robust high-frequency time series of raw atmospheric water vapor isotope data using laser spectrometry requires accurate calibration. In particular, the chemical composition of the analyzed sample gas can cause isotope bias. This study assesses the matrix effect on calibrated δ17 O, δ18 O, δ2 H, 17 O-excess, and d-excess values of atmospheric water vapor. METHODS A Picarro L2140-i cavity ring-down spectrometer with an autosampler and a vaporizer is used to analyze δ17 O, δ18 O, δ2 H, 17 O-excess, and d-excess of two water standards. Isotope data obtained using synthetic air and dry ambient air as carrier gas at water mixing ratios ranging from 2000 to 30 000 ppmv are compared. Based on the results, atmospheric water vapor measurements are calibrated. The expected precision is estimated by Monte Carlo simulation. RESULTS The dry air source strongly impacts raw isotope values of the two water standards but has no effect on the mixing ratio dependency functions. When synthetic air is used, δ17 O, δ18 O, and 17 O-excess of calibrated atmospheric water vapor are overestimated by 0.6‰, 0.7‰, and 217 per meg, respectively, whereas δ2 H and d-excess are underestimated by 1.5‰ and 7.3‰. Optimum precisions for the calibrated δ17 O, δ18 O, δ2 H, 17 O-excess, and d-excess values and 12 min integration time are 0.02‰, 0.03‰, 0.4‰, 14 per meg, and 0.4‰, respectively. CONCLUSIONS Regarding the obtained results, recommendations for the calibration of atmospheric water vapor isotope measurements are presented. The necessity to use dry ambient air as dry air source when running the standards for calibration is pointed out as a prerequisite for accurate atmospheric water vapor 17 O-excess and d-excess measurements.
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Affiliation(s)
- Claudia Voigt
- Aix Marseille Univ, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France
| | | | - Clément Piel
- ECOTRON Européen de Montpellier, UAR 3248, Centre National de la Recherche Scientifique (CNRS), Campus de Baillarguet, Montferrier-sur-Lez, France
| | - Anne Alexandre
- Aix Marseille Univ, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France
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Hachgenei N, Vaury V, Nord G, Spadini L, Duwig C. Faster and more precise isotopic water analysis of discrete samples by predicting the repetitions’ asymptote instead of averaging last values. MethodsX 2022; 9:101656. [PMID: 35330850 PMCID: PMC8938324 DOI: 10.1016/j.mex.2022.101656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 02/27/2022] [Indexed: 11/26/2022] Open
Abstract
Water stable isotope analysis using Cavity Ring-Down Spectroscopy (CRDS) has a strong between-sample memory effect. The classic approach to correct this memory effect is to inject the sample at least 6 times and ignore the first two to three injections. The average of the remaining injections is then used as measured value. This is in many cases insufficient to completely compensate the memory effect. We propose a simple approach to correct this memory effect by predicting the asymptote of consecutive repeated injections instead of averaging over them. The asymptote is predicted by fitting a y=ax+b relation to the sample repetitions and keeping b as measured value. This allows to save analysis time by doing less injections while gaining precision. We provide a Python program applying this method and describe the steps necessary to implement this method in any other programming language. We also show validation data comparing this method to the classical method of averaging over the last couple of injections. The validation suggests a gain in time of a factor two while gaining in precision at the same time. The method does not have any specific requirements for the order of analysis and can therefore also be applied to an existing set of analyzes in retrospect.We fit a simple y=ax+b relation to the sample repetitions of Picarro L2130-i isotopic water analyzer, in order to keep the asymptote (b) as measured value instead of using the average over the last couple of measurements. This allows a higher precision in the measured value with less repetitions of the injection saving precious time during analysis. We provide a sample code using Python, but generally this method is easy to implement in any automated data treatment protocol.
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Sagayama H, Racine NM, Shriver TC, Schoeller DA. Comparison of isotope ratio mass spectrometry and cavity ring-down spectroscopy procedures and precision of the doubly labeled water method in different physiological specimens. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2021; 35:e9188. [PMID: 34468057 DOI: 10.1002/rcm.9188] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 08/30/2021] [Accepted: 08/31/2021] [Indexed: 06/13/2023]
Abstract
RATIONALE This study determines if saliva collection procedures for the doubly labeled water (DLW) method, used for measuring total energy expenditure (TEE), are comparable to urine and plasma collection. Both the cavity ring-down spectroscopy (CRDS) and isotope ratio mass spectrometry (IRMS) analyses techniques are compared. METHODS Saliva specimens were collected from participants for the DLW method. The specimens were collected under different conditions: after consumption of tap water, after chewing gum, and during exposure to conditions of high and low relative humidity. The isotopes in saliva were compared with simultaneous plasma and urine collection. TEE calculated from saliva and analyzed using CRDS was compared to that of plasma analyzed using IRMS. RESULTS The within-individual variances were not significantly different between the saliva specimens (0.4‰) and plasma (0.3‰). After the oral dose of DLW, the saliva specimens displayed a shorter equilibration time to urine. When participants consumed 500 mL of tap water, the enrichment of saliva specimens reached a new plateau value faster than urine. Saliva collection exposed to high ambient humidity conditions was slightly less enriched as compared to low-humidity conditions while urine enrichment was unaffected. In contrast, whereas the within-individual effects of gum chewing during saliva collection on 18 O were unaffected, the abundance of 2 H in saliva was slightly lower after chewing the gum. The within-individual difference between TEE calculated from saliva and that calculated from plasma analyzed using IRMS did not differ from zero, and the standard deviation was not different from that predicted by a propagation of error analysis based on analytical error alone. CONCLUSIONS Our findings support using saliva specimens for the DLW method. The analysis of plasma and urine, however, requires reducing the memory effect resulting from contaminants. Also, it should be performed in a manner that minimizes exposure to air where specimens may be exposed to evaporation or contamination from water vapor during sampling.
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Affiliation(s)
- Hiroyuki Sagayama
- Faculty of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan
- Biotechnology Center, University of Wisconsin, Madison, Wisconsin, USA
| | - Natalie M Racine
- Biotechnology Center, University of Wisconsin, Madison, Wisconsin, USA
| | - Timothy C Shriver
- Biotechnology Center, University of Wisconsin, Madison, Wisconsin, USA
| | - Dale A Schoeller
- Biotechnology Center, University of Wisconsin, Madison, Wisconsin, USA
- Nutritional Sciences, University of Wisconsin, Madison, Wisconsin, USA
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