Nitrogen isotopic analyses by isotope-ratio-monitoring gas chromatography / mass spectrometry

Merritt, Dawn A.; Hayes, John M.

doi:10.1016/1044-0305(94)85054-2

Cited by 113 publications

(93 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Whereas 813C values of amino acid enantiomers can now be measured relatively easily by GC/C/IRMS, the methodology for 615N values is still presently dependent on laborintensive LC separations and subsequent conventional IRMS analyses. An additional GC/C/IRMS method for stable nitrogen isotope analyses, similar to that described herein for carbon, awaits development (42).…”

Section: Resultsmentioning

confidence: 99%

Indigeneity of organic matter in fossils: a test using stable isotope analysis of amino acid enantiomers in Quaternary mollusk shells.

Engel

Goodfriend

Qian

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Comparison of the 813C values of D and L enantfomers of individual amino acids was used to evaluate the presence of amino acid contaminants in Quaternary land snals. Measurements of 813C values of amino acid D and L enantiomers determined by combined gas chromatography, combustion, isotope-ratio mass spectrometry are reported. Conventional combustion techniques, following separation of aspartic acid and glutamic acid enantiomers by liquid chromatography, were also used to determine 813C as well as 815N values. Thoroughly cleaned samples ranging in age from 7000 to >100,000 yr B.P. are shown to have analytically identical 813C values for the D and L enantiomers of each amino add, thus confirming that the amino acids are indigenous to the shells, even in Pleistocene samples. On the other hand, partially cleaned material shows divergence of isotopic values, thus indicating the presence of amino acid contaminants and emphasing the importance of proper cleaning procedures. This approach provides a powerful method for assessing the indigeneity of amino adds in fossils.A variety of types of studies depend on the assumption that the organic constituents of fossils are indigenous. These include amino acid racemization/epimerization dating of marine (1), terrestrial (2, 3), and freshwater (4) samples, paleotemperature estimation from amino acid racemization rates (5), analysis offree amino acid concentrations for dating (6), taxonomic studies (7,8), and reconstruction ofpaleodiets (9,10) and paleoclimates (11-13) from the stable isotope composition of organic matter.Indigeneity has previously been assessed by a variety of methods, no one of which has proved particularly reliable. Relative abundances of amino acids in fossils have been compared to modern samples ofrelated species (14, 15). Such comparisons, however, are problematic because even in uncontaminated material, the proportions of the various amino acids will change over time as a result of more rapid breakdown of the less stable ones, such as serine, threonine, and aspartic acid. Amounts of amino acids may decrease by several orders of magnitude over thousands to millions of years (3,(15)(16)(17). The extent of racemization of amino acids has also been used to assess indigeneity, with the criterion being that very old samples should show equilibrium ratios of D/L amino acid enantiomers if they are uncontaminated (18).But racemization rates may be very reduced in certain molecular components (19,20), especially where the amino acids have undergone condensation reactions with sugars (21). Microscopic examination has been used to show that the fossil matrix has been physically preserved (22,23), but microstructure is not sensitive to either chemical preservation or the presence of contaminants (23). The similarity of the stable carbon and nitrogen isotope composition of bulk fossil organic matter to modern samples (24) and their dissimilarity to the sedimentary matrix (25) have also been used to indicate indigeneity of organic matter. As the amino acid comp...

show abstract

Section: Resultsmentioning

confidence: 99%

Indigeneity of organic matter in fossils: a test using stable isotope analysis of amino acid enantiomers in Quaternary mollusk shells.

Engel

Goodfriend

Qian

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…Nitrogen isotopic analysis is also based on combustion of analytes, followed obligately by reduction of NO X to N 2 [61][62][63]. Conveniently, the conversion can be accomplished using the same combination of combustion/ reduction reactors that are used for carbon (above) so that both types of analyses can be performed using the same interface.…”

Section: Nitrogen Isotopesmentioning

confidence: 99%

“…An additional problem for N-isotopic analyses is that CO 2 entering the IRMS produces significant ion-currents at m/z 28 and 29 due to CO + fragments. CO 2 must therefore be removed from the carrier gas stream, generally by cryogenic trapping [26,61,63].…”

Section: Nitrogen Isotopesmentioning

confidence: 99%

Isotope‐ratio detection for gas chromatography

Sessions¹

2006

J of Separation Science

244

270

View full text Add to dashboard Cite

Isotope-ratio detection for gas chromatographyInstrumentation and methods exist for highly precise analyses of the stable-isotopic composition of organic compounds separated by GC. The general approach combines a conventional GC, a chemical reaction interface, and a specialized isotoperatio mass spectrometer (IRMS). Most existing GC hardware and methods are amenable to isotope-ratio detection. The interface continuously and quantitatively converts all organic matter, including column bleed, to a common molecular form for isotopic measurement. C and N are analyzed as CO 2 and N 2 , respectively, derived from combustion of analytes. H and O are analyzed as H 2 and CO produced by pyrolysis/reduction. IRMS instruments are optimized to provide intense, highly stable ion beams, with extremely high precision realized via a system of differential measurements in which ion currents for all major isotopologs are simultaneously monitored. Calibration to an internationally recognized scale is achieved through comparison of closely spaced sample and standard peaks. Such systems are capable of measuring 13 C/ 12 C ratios with a precision approaching 0.1? (for values reported in the standard delta notation), four orders of magnitude better than that typically achieved by conventional "organic" mass spectrometers. Detection limits to achieve this level of precision are typically a1 nmol C (roughly 10 ng of a typical hydrocarbon) injected on-column. Achievable precision and detection limits are correspondingly higher for N, O, and H, in that order.

show abstract

“…However, CSIA of amino acids is limited to only a few numbers of studies, which include several nitrogen CSIA of amino acids (e.g., Brand et al 1994;Elsila et al 2012;Engel and Macko 1997;Merritt and Hayes 1994;Pizzarello et al 1994;Pizzarello and Holmes 2009;Preston and Slater 1994). In these studies, CSIA has not only been used to interpret the origins of individual amino acids but also as a guide to their formation pathways, as the isotopic values are correlated to the precursors and formation mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Amino acid compositions in heated carbonaceous chondrites and their compound-specific nitrogen isotopic ratios

et al. 2016

View full text Add to dashboard Cite

A novel method has been developed for compound-specific nitrogen isotope compositions with an achiral column which was previously shown to offer high precision for nitrogen isotopic analysis. We applied the method to determine the amino acid contents and stable nitrogen isotopic compositions of individual amino acids from the thermally metamorphosed (above 500°C) Antarctic carbonaceous chondrites Ivuna-like (CI)1 (or CI-like) Yamato (Y) 980115 and Ornans-like (CO)3.5 Allan Hills (ALH) A77003 with the use of gas chromatography/combustion/isotope ratio mass spectrometry. ALHA77003 was deprived of amino acids due to its extended thermal alteration history. Amino acids were unambiguously identified in Y-980115, and the δ 15 N values of selected amino acids (glycine +144.8 ‰; α-alanine +121.2 ‰) are clearly extraterrestrial. Y-980115 has experienced an extended period of aqueous alteration as indicated by the presence of hydrous mineral phases. It has also been exposed to at least one post-hydration short-lived thermal metamorphism. Glycine and alanine were possibly produced shortly after the accretion event of the asteroid parent body during the course of an extensive aqueous alteration event and have abstained from the short-term post-aqueous alteration heating due to the heterogeneity of the parent body composition and porosity. These carbonaceous chondrite samples are good analogs that offer important insights into the target asteroid Ryugu of the Hayabusa-2 mission, which is a C-type asteroid likely composed of heterogeneous materials including hydrated and dehydrated minerals.

show abstract

Nitrogen isotopic analyses by isotope-ratio-monitoring gas chromatography / mass spectrometry

Cited by 113 publications

References 28 publications

Indigeneity of organic matter in fossils: a test using stable isotope analysis of amino acid enantiomers in Quaternary mollusk shells.

Indigeneity of organic matter in fossils: a test using stable isotope analysis of amino acid enantiomers in Quaternary mollusk shells.

Isotope‐ratio detection for gas chromatography

Amino acid compositions in heated carbonaceous chondrites and their compound-specific nitrogen isotopic ratios

Contact Info

Product

Resources

About