Methods and limitations of stable isotope measurements via direct elution of chromatographic peaks using gas chromotography-Orbitrap mass spectrometry

Zeichner, Sarah S.; Wilkes, Elise B.; Hofmann, Amy E.; Chimiak, Laura; Sessions, Alex L.; Makarov, Alexander; Eiler, John M.

doi:10.1016/j.ijms.2022.116848

Cited by 19 publications

(13 citation statements)

References 38 publications

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“…This platform employed a Thermo Scientific TRACE™ 1310 GC equipped with split/splitless injector. Peaks eluting directly off the GC column have been explored for isotope analysis, illustrating that the achievable precision is limited by the number of ions (10 4 –10 5 ) observed per scan in the Orbitrap and the width of the chromatographic peak (in time) 43 . Our application therefore required a distinct instrumental setup to achieve the desired precision (i.e.…”

Section: Methodsmentioning

confidence: 99%

Position‐specific carbon isotope analysis of serine by gas chromatography/Orbitrap mass spectrometry, and an application to plant metabolism

Wilkes

Sessions

Zeichner

et al. 2022

Rapid Comm Mass Spectrometry

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Rationale Position‐specific 13C/12C ratios within amino acids remain largely unexplored in environmental samples due to methodological limitations. We hypothesized that natural‐abundance isotope patterns in serine may serve as a proxy for plant metabolic fluxes including photorespiration. Here we describe an Orbitrap method optimized for the position‐specific carbon isotope analysis of serine to test our hypothesis and discuss the generalizability of this method to other amino acids. Methods Position‐specific carbon isotope ratios of serine were measured using a Thermo Scientific™ Q Exactive™ GC Orbitrap™. Amino acids were hydrolyzed from Arabidopsis biomass, purified from potential matrix interferences, and derivatized alongside standards. Derivatized serine (N,O‐bis(trifluoroacetyl)methyl ester) was isolated using gas chromatography, trapped in a reservoir, and purged into the electron ionization source over tens of minutes, producing fragment ions containing different combinations of atoms from the serine‐derivative molecule. The 13C/12C ratios of fragments with monoisotopic masses of 110.0217, 138.0166, and 165.0037 Da were monitored in the mass analyzer and used to calculate position‐specific δ13C values relative to a working standard. Results This methodology constrains position‐specific δ13C values for nanomole amounts of serine isolated from chemically complex mixtures. The δ13C values of fragment ions of serine were characterized with ≤1‰ precisions, leading to propagated standard errors of 0.7–5‰ for each carbon position. Position‐specific δ13C values differed by up to ca 28 ± 5‰ between serine molecules hydrolyzed from plants grown under contrasting pCO2, selected to promote different fluxes through photosynthesis and photorespiration. The method was validated using pure serine standards characterized offline. Conclusions This study presents the first Orbitrap‐based measurements of natural‐abundance, position‐specific carbon isotope variation in an amino acid isolated from a biological matrix. We present a method for the precise characterization of isotope ratios in serine and propose applications probing metabolism in plants. We discuss the potential for extending these approaches to other amino acids, paving the way for novel applications.

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Section: Methodsmentioning

confidence: 99%

Position‐specific carbon isotope analysis of serine by gas chromatography/Orbitrap mass spectrometry, and an application to plant metabolism

Wilkes

Sessions

Zeichner

et al. 2022

Rapid Comm Mass Spectrometry

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“…We measured the d 13 C VPDB values of the five PAHs previously identified in Hayabusa2 sample A0106 and the d 13 C VPDB , dD VSMOW and D2× 13 C values of the same five PAHs from C0107 (21). We compared these measurements with those of fluoranthene and pyrene extracted from the CC meteorite Murchison (21,31). We also measured d 13 C VPDB and D2× 13 C values of combusted plant biomass as a high-temperature comparison (21).…”

Section: Abundancesmentioning

confidence: 99%

“…We analyzed PAHs within the same DCM extracts of Ryugu as those previous studies ( 22 , 30 ) using gas chromatography coupled with Orbitrap mass spectrometry (GC-Orbitrap) ( 31 ). We measured the δ 13 C VPDB values of the five PAHs previously identified in Hayabusa2 sample A0106 and the δ 13 C VPDB , δD VSMOW and Δ2× 13 C values of the same five PAHs from C0107 ( 21 ).…”

Section: Isotopic Measurements Of Pah Samplesmentioning

confidence: 99%

Polycyclic aromatic hydrocarbons in samples of Ryugu formed in the interstellar medium

Zeichner,

Aponte,

Bhattacharjee

et al. 2023

Science

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Polycyclic aromatic hydrocarbons (PAHs) contain ≲20% of the carbon in the interstellar medium. They are potentially produced in circumstellar environments (at temperatures ≳1000 kelvin), by (~10 kelvin) interstellar clouds, or by processing of carbon-rich dust grains. We report isotopic properties of PAHs extracted from samples of the asteroid Ryugu and the meteorite Murchison. The doubly- 13 C substituted compositions (Δ2× 13 C values) of the PAHs naphthalene, fluoranthene, and pyrene are 9 to 51‰ higher than values expected for a stochastic distribution of isotopes. The Δ2× 13 C values are higher than expected if the PAHs formed in a circumstellar environment, but consistent with formation in the interstellar medium. By contrast, the PAHs phenanthrene and anthracene in Ryugu samples have Δ2× 13 C values consistent with formation by higher-temperature reactions.

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“…Compositional measurements with mass spectrometry involve ionizing the sample molecules, which is complicated by high concentrations of background ions in the sample, such as salts. Mass spectrometers have a limited volume of ions that can be analyzed, and unwanted salt ions can effect interactions that can diminish the sensitivity and accuracy of the instrument, and reduce the ability of the mass spectrometer to detect and quantify molecules of interest (Zeichner et al., 2022). Salts can also impede the ionization of biological molecules through suppression or breakdown of the molecule during ionization (Donnelly et al., 2019; Duncan et al., 2019; Metwally et al., 2015).…”

Section: Introductionmentioning

confidence: 99%

Development of the Miniature Robotic Electrodialysis (MR ED) System for Small‐Scale Desalting of Liquid Samples With Recovery of Organics

Bryson

Ingall

Hanna

et al. 2023

Earth and Space Science

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While liquid environments with high salt content are of broad interest to the Earth and Planetary Science communities, instruments face challenges in detecting organics in hypersaline samples due to the effects of salts. Therefore, technology to desalt samples before analysis by these instruments would be enabling for liquid sampling on missions to Mars or ocean worlds. Electrodialysis (ED) removes salt from aqueous solutions by applying an electric potential across a series of ion‐selective membranes, and is demonstrated to retain a significant percentage of dissolved organic molecules (DOM) in marine samples. However, current electrodialysis systems used for DOM recovery are too large for deployment on missions or for use in terrestrial fieldwork. Here, we present the design and evaluation of the Miniature Robotic Electrodialysis (MR ED) system, which is approximately 1/20th the size of heritage instruments and processes as little as 50 mL of sample at a time. We present tests of the instrument efficiency and DOM recovery using lab‐created solutions as well as natural samples taken from an estuary of the Skidaway River (Savannah, GA) (Verity, 2002) and from South Bay Saltworks (San Diego, CA) (Roseman & Watry, 2008; Survey, 2011). Our results show that the MR ED system removed 97%–99% of the salts in most samples, with an average DOC recovery range from 53% to 77%, achieving similar capability to tabletop instruments. This work both demonstrates MR ED as a possible field instrument and increases the technology readiness level of miniaturized electrodialysis systems for future missions.

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Methods and limitations of stable isotope measurements via direct elution of chromatographic peaks using gas chromotography-Orbitrap mass spectrometry

Cited by 19 publications

References 38 publications

Position‐specific carbon isotope analysis of serine by gas chromatography/Orbitrap mass spectrometry, and an application to plant metabolism

Position‐specific carbon isotope analysis of serine by gas chromatography/Orbitrap mass spectrometry, and an application to plant metabolism

Polycyclic aromatic hydrocarbons in samples of Ryugu formed in the interstellar medium

Development of the Miniature Robotic Electrodialysis (MR ED) System for Small‐Scale Desalting of Liquid Samples With Recovery of Organics

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