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Martin C, Richter N, Lloren R, Dubois N. Impact of saponification and silver-nitrate purification on lacustrine alkenone distributions and alkenone-based indices. J Chromatogr A 2024; 1715:464576. [PMID: 38171064 DOI: 10.1016/j.chroma.2023.464576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 11/28/2023] [Accepted: 12/11/2023] [Indexed: 01/05/2024]
Abstract
A growing interest in lacustrine alkenones as a proxy for continental paleotemperature reconstructions accompanied important methodological improvements over the past two decades. New gas chromatography (GC) columns were used for alkenone analysis, that drastically improved alkenone separation, especially for freshwater lakes. However, these recent advances are sometimes not sufficient in separating compounds that interfere with alkenones in the resulting chromatograms and concurrently, new chemical procedures were implemented to further clean up the samples. Here we investigate the impact of two clean-up procedures, saponification and silver-nitrate purification, on alkenone distribution, alkenone quantification, and C37 alkenone-based indices, including the U37K index. The silver-nitrate purification modified the C37 alkenone distribution and thus the C37 alkenone-based indices, especially the U37K index, in 6 out of the 9 studied samples by further retaining alkenones with more double bonds. These changes would result on an average error of 3 °C in reconstructed temperatures. Saponification also influenced the C37 alkenone distribution mainly by removing co-eluting compounds, thereby improving the quality of the results. Both saponification and purification resulted in the reduction of the C37 alkenone concentration by almost half. Clean-up steps should thus be used carefully, paying particular attention to any change in alkenone distribution and concentration. Limiting the use of additional clean-up steps reduces the risk of modifying the alkenone distribution.
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Affiliation(s)
- Céline Martin
- Surface Waters Research + Management, Eawag, Überlandstrasse 133, Dübendorf CH-8600, Switzerland.
| | - Nora Richter
- Department of Marine Microbiology and Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research, 1790 AB Den Burg, the Netherlands
| | - Ronald Lloren
- Surface Waters Research + Management, Eawag, Überlandstrasse 133, Dübendorf CH-8600, Switzerland
| | - Nathalie Dubois
- Surface Waters Research + Management, Eawag, Überlandstrasse 133, Dübendorf CH-8600, Switzerland
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Liao S, Liu XL, Manz KE, Pennell KD, Novak J, Santos E, Huang Y. Comprehensive analysis of alkenones by reversed-phase HPLC-MS with unprecedented selectivity, linearity and sensitivity. Talanta 2023; 260:124653. [PMID: 37178676 DOI: 10.1016/j.talanta.2023.124653] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 05/03/2023] [Accepted: 05/04/2023] [Indexed: 05/15/2023]
Abstract
Alkenones are among the most widely used paleotemperature biomarkers. Traditionally, alkenones are analyzed using gas chromatography-flame ionization detector (GC-FID), or GC-chemical ionization-mass spectrometry (GC-CI-MS). However, these methods encounter considerable challenges for samples that exhibit matrix interference or low concentrations, with GC-FID requiring tedious sample preparations and GC-CI-MS suffering from nonlinear response and a narrow linear dynamic range. Here we demonstrate that reversed-phase high pressure liquid chromatography-mass spectrometry (HPLC-MS) methods provide excellent resolution, selectivity, linearity and sensitivity for alkenones in complex matrices. We systematically compared the advantages and limitations of three mass detectors (quadrupole, Orbitrap, and quadrupole-time of flight) and two ionization modes (electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI)) for alkenone analyses. We demonstrate that ESI performs better than APCI as response factors of various unsaturated alkenones are similar. Among the three mass analyzers tested, orbitrap MS provided the lowest limit of detection (0.4, 3.8 and 8.6 pg injected masses for Orbitrap, qTOF and single quadrupole MS, respectively) and the widest linear dynamic range (600, 20 and 30 folds for Orbitrap, qTOF and single quadrupole MS, respectively). Single quadrupole MS operated in ESI mode provides accurate quantification of proxy measurements over a wide range of injection masses, and with its modest instrument cost, represents an ideal method for routine applications. Analysis of global core-top sediment samples confirmed the efficacy of HPLC-MS methods for the detection and quantification of paleotemperature proxies based on alkenones and their superiority over GC-based methods. The analytical method demonstrated in this study should also allow highly sensitive analyses of diverse aliphatic ketones in complex matrices.
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Affiliation(s)
- Sian Liao
- Department of Chemistry, Brown University, 324 Brook Street, Providence, RI, 02912, USA
| | - Xiao-Lei Liu
- School of Geosciences, University of Oklahoma, 100 E. Boyd Street, Norman, OK, 73019, USA
| | - Katherine E Manz
- School of Engineering, Brown University, 345 Brook Street, Providence, RI, 02912, USA
| | - Kurt D Pennell
- School of Engineering, Brown University, 345 Brook Street, Providence, RI, 02912, USA
| | - Joseph Novak
- Ocean Sciences Department, University of California, Santa Cruz, CA, 95064, USA
| | - Ewerton Santos
- Department of Earth, Environmental and Planetary Sciences, Brown University, 324 Brook Street, Providence, RI, 02912, USA
| | - Yongsong Huang
- Department of Earth, Environmental and Planetary Sciences, Brown University, 324 Brook Street, Providence, RI, 02912, USA.
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Combination of Medium- and High-Pressure Liquid Chromatography for Isolation of L-tryptophan (Q-marker) from Medicago sativa Extract. SEPARATIONS 2022. [DOI: 10.3390/separations9090240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Medicago sativa (alfalfa) is a widely used animal feed. However, its quality has been difficult to control due to the lack of appropriate marker compounds. Therefore, it is very necessary to select an appropriate quality marker (Q-marker) to control its quality. In this study, medium-pressure liquid chromatography and high-pressure liquid chromatography were employed to effectively prepare the separation of the Q-marker (L-tryptophan) from Medicago sativa. Firstly, using MCI GEL® CHP20P as the stationary phase, 2.5 g of the target fraction Fr3 was enriched from crude Medicago sativa extract (2.9 kg) by medium-pressure liquid chromatography. Secondly, Sephadex LH-20 was used to further separate Fr3 fractions, and the Fr34 fraction (358.3 mg) was enriched after 14 repetitions. Lastly, using the ReproSil-Pur C18 AQ preparative column, 63.4 mg of L-tryptophan was obtained by high-pressure liquid chromatography, and the purity was above 95%. The results showed that medium-pressure liquid chromatography (MCI GEL® CHP20P and Sephadex LH-20) combined with high-pressure liquid chromatography (ReproSil-Pur C18 AQ) could be used to effectively prepare the Q-marker from natural products with satisfactory purity.
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Wang KJ, Huang Y, Majaneva M, Belt ST, Liao S, Novak J, Kartzinel TR, Herbert TD, Richter N, Cabedo-Sanz P. Group 2i Isochrysidales produce characteristic alkenones reflecting sea ice distribution. Nat Commun 2021; 12:15. [PMID: 33397905 PMCID: PMC7782803 DOI: 10.1038/s41467-020-20187-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 11/12/2020] [Indexed: 01/29/2023] Open
Abstract
Alkenones are biomarkers produced solely by algae in the order Isochrysidales that have been used to reconstruct sea surface temperature (SST) since the 1980s. However, alkenone-based SST reconstructions in the northern high latitude oceans show significant bias towards warmer temperatures in core-tops, diverge from other SST proxies in down core records, and are often accompanied by anomalously high relative abundance of the C37 tetra-unsaturated methyl alkenone (%C37:4). Elevated %C37:4 is widely interpreted as an indicator of low sea surface salinity from polar water masses, but its biological source has thus far remained elusive. Here we identify a lineage of Isochrysidales that is responsible for elevated C37:4 methyl alkenone in the northern high latitude oceans through next-generation sequencing and lab-culture experiments. This Isochrysidales lineage co-occurs widely with sea ice in marine environments and is distinct from other known marine alkenone-producers, namely Emiliania huxleyi and Gephyrocapsa oceanica. More importantly, the %C37:4 in seawater filtered particulate organic matter and surface sediments is significantly correlated with annual mean sea ice concentrations. In sediment cores from the Svalbard region, the %C37:4 concentration aligns with the Greenland temperature record and other qualitative regional sea ice records spanning the past 14 kyrs, reflecting sea ice concentrations quantitatively. Our findings imply that %C37:4 is a powerful proxy for reconstructing sea ice conditions in the high latitude oceans on thousand- and, potentially, on million-year timescales.
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Affiliation(s)
- Karen Jiaxi Wang
- grid.40263.330000 0004 1936 9094Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912 USA ,grid.40263.330000 0004 1936 9094Institute at Brown for Environment and Society, Brown University, Providence, RI 02912 USA
| | - Yongsong Huang
- grid.40263.330000 0004 1936 9094Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912 USA ,grid.40263.330000 0004 1936 9094Institute at Brown for Environment and Society, Brown University, Providence, RI 02912 USA
| | - Markus Majaneva
- grid.420127.20000 0001 2107 519XNorwegian Institute for Nature Research (NINA), NO-7485 Trondheim, Norway
| | - Simon T. Belt
- grid.11201.330000 0001 2219 0747Biogeochemistry Research Centre, School of Geography, Earth and Environmental Sciences, Plymouth University, Plymouth, PL4 8AA UK
| | - Sian Liao
- grid.40263.330000 0004 1936 9094Institute at Brown for Environment and Society, Brown University, Providence, RI 02912 USA ,grid.40263.330000 0004 1936 9094Department of Chemistry, Brown University, Providence, RI 02912 USA
| | - Joseph Novak
- grid.40263.330000 0004 1936 9094Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912 USA
| | - Tyler R. Kartzinel
- grid.40263.330000 0004 1936 9094Institute at Brown for Environment and Society, Brown University, Providence, RI 02912 USA ,grid.40263.330000 0004 1936 9094Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912 USA
| | - Timothy D. Herbert
- grid.40263.330000 0004 1936 9094Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912 USA ,grid.40263.330000 0004 1936 9094Institute at Brown for Environment and Society, Brown University, Providence, RI 02912 USA
| | - Nora Richter
- grid.40263.330000 0004 1936 9094Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912 USA ,grid.40263.330000 0004 1936 9094Institute at Brown for Environment and Society, Brown University, Providence, RI 02912 USA ,grid.10914.3d0000 0001 2227 4609Department of Marine Microbiology and Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research, Texel, The Netherlands
| | - Patricia Cabedo-Sanz
- grid.11201.330000 0001 2219 0747Biogeochemistry Research Centre, School of Geography, Earth and Environmental Sciences, Plymouth University, Plymouth, PL4 8AA UK
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Yıldırım S, Erkmen C, Uslu B. Novel Trends in Analytical Methods for β-Blockers: An Overview of Applications in the Last Decade. Crit Rev Anal Chem 2020; 52:131-169. [DOI: 10.1080/10408347.2020.1791043] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Sercan Yıldırım
- Faculty of Pharmacy, Department of Analytical Chemistry, Karadeniz Technical University, Trabzon, Turkey
| | - Cem Erkmen
- Faculty of Pharmacy, Department of Analytical Chemistry, Ankara University, Ankara, Turkey
| | - Bengi Uslu
- Faculty of Pharmacy, Department of Analytical Chemistry, Ankara University, Ankara, Turkey
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