Chemical characterization of dissolved organic matter (DOM) in seawater : structure, cycling, and the role of biology

Quan, Tracy M.

doi:10.1575/1912/1569

Cited by 6 publications

(6 citation statements)

References 56 publications

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“…δ 15 N side values for them may be determined from mass balance in combination with methods to determine total δ 15 N. Site‐specific δ 15 N for other important amino‐N‐containing compounds such as ornithine (an analogue of Lys) and aliphatic amines is likely to be obtained by a similar approach. Hypochlorite oxidation of AAs should be readily coupled to preparative high‐performance liquid chromatography (HPLC) separation,22 a more robust and simpler technique than GC for this application. This scheme also permits flexibility in focusing analytical effort on individual AAs of interest whereas GC‐C‐IRMS requires derivatization and separation of all AAs present.…”

Section: Discussionmentioning

confidence: 99%

Amino‐group‐specific natural abundance nitrogen isotope ratio analysis in amino acids

Zhang

Altabet

2008

Rapid Comm Mass Spectrometry

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Amino acid (AA) nitrogen (N) stable isotope ratio analysis has found a wide variety of important applications including indication of the trophic level of an organism, tracing N transfer within food webs, and monitoring of AA resynthesis during heterotrophic microbial reworking of organic matter. Despite its utility, the current methodology is difficult to employ consistently for natural abundance level precision. Here, we report a new and robust method for high-precision N-compound-specific isotope analysis (N-PCIA) for single-N-containing AAs and N-position-specific isotope analysis (N-PSIA) for poly-N AAs. First the amino-N in AAs was liberated and oxidized to NO2(-) by hypochlorite at high pH. The NO2(-) produced was then quantified colorimetrically with excess hypochlorite quenched using arsenite. Subsequently, buffered azide was used to reduce NO2(-) to N2O for isotope ratio analysis using a purge-and-trap isotope ratio mass spectrometer. In the case of glycine delta15N, the average precision was SD = 0.3 per thousand. Reaction yields and labeling experiments show that this oxidation reaction is highly specific, targeting the alpha-amino group (peptide-N) of most poly-N AAs. This permits specific determination of the delta15N of peptide-N in arginine, tryptophan, and histidine. In the case of lysine, however, the side-chain amino group was found to be partially labile to hypochlorite oxidation. Using isotope fractionation factors estimated from single-N analogues of lysine, the intramolecular delta15N of lysine was calculated by mass balance, and this generally agreed with results for the same sample material analyzed by a previously published enzymatic method. Our method has the advantages of being relatively rapid, robust, and applicable to all poly-N AAs. We have also found it to work well for determining total delta15N of amino-N in complex sample matrices that have not been susceptible to previous approaches.

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Section: Discussionmentioning

confidence: 99%

Amino‐group‐specific natural abundance nitrogen isotope ratio analysis in amino acids

Zhang

Altabet

2008

Rapid Comm Mass Spectrometry

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“…The hydrolyzates were eluted through ion exchange columns for separation of THAA and TCHO from each other. (Further analyses of THAA fraction isolated by this method proved that this fraction contained other minor compounds as well [ Quan , 2005]. However, this method is valid for our purpose of separation of labile, hydrolyzable, amino acids‐like material.)…”

Section: Sample Collection and Analysesmentioning

confidence: 99%

Transport of organic carbon from the California coast to the slope region: A study of Δ¹⁴C and δ¹³C signatures of organic compound classes

Hwang

Druffel

Komada

2005

Global Biogeochemical Cycles

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[1] Surface sediments along a transect from an abyssal site in the northeastern Pacific (Station M, 34°50 0 N, 123°00 0 W) to a small mountainous river on the California coast (Santa Clara River) were studied to investigate the sources and cycling of organic matter on the continental margin. Sediment samples were separated into organic compound fractions (extractable lipids, amino acids (THAA), carbohydrates (TCHO), and the acid-insoluble fraction), and their carbon isotope ratios were measured. The D 14 C values of all the THAA and TCHO fractions were greater than À100%, indicating relatively modern organic carbon (OC) source(s), and rapid cycling of these fractions. In contrast, the D 14 C values of extractable lipids and the acid-insoluble fraction were distinctly lower than those of the THAA and TCHO fractions. The D 14 C values of source OC to the sediments were estimated using a simple mixed layer model. These values were lower than the D 14 C signatures of pre-industrial plankton suggesting input of both old OC and contemporary plankton to the margin sediments. The source of old OC at the 2000-m site was likely from laterally transported coastal sediment. The estimated low D 14 C value of the transported OC suggests that old lipids and acid-insoluble material were selectively transported to the 2000-m site. The contribution of riverine POC to the margin sediments were estimated from D 14 C and d 13 C values and indicate that relict OC exported by rivers was an important source of old lipids and acid-insoluble material to sedimentary OC on the shelf.

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“…The two liquid chromatographic isolation steps following the desalting procedure are necessary given the presence of other compounds in fractions isolated by the first separation. The same conclusion was reached previously in complex environmental matrices (high molecular weight dissolved organic matter), which contained impurities including, among others, monosaccharides and deoxy sugars (Quan, 2005). In contrast to Quan (2005), who used a cation exchange resin after reversed phase chromatography, a mixed mode cation exchange-reversed phase column chemistry was used here.…”

Section: Chromatographic Separationmentioning

confidence: 69%

“…However, the information contained in their amino acid-specific radiocarbon content has hitherto remained sparingly investigated. For amino acids, procedures for analyzing their compound-specific radiocarbon content have been developed for dissolved organic matter (Quan, 2005), collagen (Tripp et al, 2006), and for animal tissue (Ishikawa et al, 2018). Motivated by the prospect of exploring new research frontiers in biogeochemistry including food webs and organic mattermineral interactions (Blattmann and Ishikawa, Unpublished), we report a method to conduct compound-specific radiocarbon on amino acids extracted from sediments.…”

Section: Introductionmentioning

confidence: 99%

Liquid Chromatographic Isolation of Individual Amino Acids Extracted From Sediments for Radiocarbon Analysis

et al. 2020

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The "building blocks of life" are found nearly ubiquitously in the environment in the form of proteins, peptides, and single amino acids. To shed light on amino acid sources, cycling, and preservation in sedimentary environments, we present a method using high-pressure liquid chromatography to separate and isolate underivatized amino acids extracted from sediments to conduct compound-specific radiocarbon analysis. This method consists of three main steps including (1) amino acid extraction by hydrofluoric and hydrochloric acids followed by desalting, (2) liquid chromatographic isolation and purification using two complementary column chemistries, and (3) post-purification and measurement by accelerator mass spectrometry. The resulting blank of this procedure is estimated to contain 2.2 ± 1.3 µgC with 0.25 ± 0.09 Fm.

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Chemical characterization of dissolved organic matter (DOM) in seawater : structure, cycling, and the role of biology

Cited by 6 publications

References 56 publications

Amino‐group‐specific natural abundance nitrogen isotope ratio analysis in amino acids

Amino‐group‐specific natural abundance nitrogen isotope ratio analysis in amino acids

Transport of organic carbon from the California coast to the slope region: A study of Δ¹⁴C and δ¹³C signatures of organic compound classes

Liquid Chromatographic Isolation of Individual Amino Acids Extracted From Sediments for Radiocarbon Analysis

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Chemical characterization of dissolved organic matter (DOM) in seawater : structure, cycling, and the role of biology

Cited by 6 publications

References 56 publications

Amino‐group‐specific natural abundance nitrogen isotope ratio analysis in amino acids

Amino‐group‐specific natural abundance nitrogen isotope ratio analysis in amino acids

Transport of organic carbon from the California coast to the slope region: A study of Δ14C and δ13C signatures of organic compound classes

Liquid Chromatographic Isolation of Individual Amino Acids Extracted From Sediments for Radiocarbon Analysis

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Transport of organic carbon from the California coast to the slope region: A study of Δ¹⁴C and δ¹³C signatures of organic compound classes