scholarly journals Errors associated with compound‐specific δ 15 N analysis of amino acids in preserved fish samples purified by high‐pressure liquid chromatography

2020 ◽  
Vol 18 (6) ◽  
pp. 259-270
Author(s):  
Rasmus Swalethorp ◽  
Lihini Aluwihare ◽  
Andrew R. Thompson ◽  
Mark D. Ohman ◽  
Michael R. Landry
Keyword(s):  
Amino Acids ◽  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
Fish Samples

scholarly journals Errors associated with compound specific δ15N analysis of amino acids in preserved fish samples purified by high pressure liquid chromatography

2019 ◽  
Author(s):  
Rasmus Swalethorp ◽  
Lihini Aluwihare ◽  
Andrew R. Thompson ◽  
Mark D. Ohman ◽  
Michael R. Landry
Keyword(s):  
Amino Acids ◽  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
Trophic Position ◽  
Isotope Ratio Mass Spectrometry ◽  
Isotopic Analysis ◽  
Trophic Dynamics ◽  
Fish Samples ◽  
Northern Anchovy

AbstractCompound specific isotopic analysis of amino acids (CSIA-AA) is increasingly used in ecological and biogeochemical studies tracking the origin and fate of nitrogen (N). Its advantages include the potential for resolving finer-scale trophic dynamics than possible with standard bulk SIA and for reconstructing historical changes in the food webs of consumers from analyses of specimens in preserved sample archives. For the latter, assessing the effects of chemical preservatives on δ15NAA has been inconclusive because the conventional CSIA approach for derivatized AAs by gas chromatography – combustion – isotope ratio mass spectrometry (GC-C-IRMS) has analytical errors (0.4 - 1.0 ‰) in the range expected from chemical preservation. Here, we show improved analytical precision (0.15 ± 0.08 ‰) for 11 underivatized AA standards analyzed by high pressure liquid chromatography followed by offline elemental analysis – IRMS (HPLC/EA-IRMS), an approach originally developed by Broek and McCarthy (2014). Using this method, we report the first high-precision tests of preservation effects on δ15NAA in Northern Anchovy (Engraulis mordax) kept 1½-year in ethanol and up to 27-years in formaldehyde. We found minimal methodological induced fractionation for 8 AAs, and preservation effects on δ15N were similar regardless of duration and preservative used. Although some of the AAs differed significantly from frozen control samples (average +1.0 ± 0.8 ‰), changes in δ15N in the source AA Phenylalanine and trophic position estimates were statistically insignificant. Our results are encouraging for resolving fine-scale natural variability using HPLC/EA-IRMS on chemically preserved specimens and for ultimately reconstructing biogeochemical records and trophic dynamics over long time scales.

scholarly journals Quantitative profiling of 1-Carbon Metabolites, Amino Acids and Precursors, and Plasmalogens in human plasma using Ultra-High-Pressure Liquid Chromatography coupled with Tandem Mass Spectrometry and robotic compound extraction

2019 ◽  
Author(s):  
Stephanie Andraos ◽  
Michael Goy ◽  
Ben Albert ◽  
Martin Kussmann ◽  
Eric B. Thorstensen ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Amino Acids ◽  
High Pressure ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Human Plasma ◽  
High Pressure Liquid Chromatography ◽  
Reversed Phase ◽  
Tandem Mass ◽  
Ultra High Pressure

AbstractAmino acids (AAs) and one-carbon (1-C) compounds are involved in a range of key metabolic pathways, and mediate numerous health and disease processes in the human body. Previous assays have quantified a limited selection of these compounds. Here, we describe an analytical method for the simultaneous quantification of 37 1-C metabolites, amino acids, precursors, and plasmalogens using reversed-phase ultra-high pressure liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). Compound extraction from human plasma was tested manually before being robotically automated. The final analytical panel was validated on human plasma samples. Our automated and multiplexed method holds promise for application to large cohort studies.

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