Quantification of glycine betaine, choline and trimethylamine N-oxide in seawater particulates: Minimisation of seawater associated ion suppression

Abstract

h i g h l i g h t s g r a p h i c a l a b s t r a c tLC/MS method for measuring glycine betaine, choline and TMAO in particulates from seawater. The sensitivity of this method at the low nanomolar range permits its use for studies into the cycling of Nosmolytes. Approaches to reduce ion suppression during LC/MS of marine extracts are presented.a r t i c l e i n f o b s t r a c tA liquid chromatography/mass spectrometry (LC/MS, electrospray ionisation) method has been developed for the quantification of nitrogenous osmolytes (N-osmolytes) in the particulate fraction of natural water samples. Full method validation demonstrates the validity of the method for measuring glycine betaine (GBT), choline and trimethylamine N-oxide (TMAO) in particulates from seawater. Limits of detection were calculated as 3.5, 1.2 and 5.9 pg injected onto column (equivalent to 1.5, 0.6 and 3.9 nmol per litre) for GBT, choline and TMAO respectively. Precision of the method was typically 3% for both GBT and choline and 6% for TMAO. Collection of the particulate fraction of natural samples was achieved via in-line filtration. Resulting chromatography and method sensitivity was assessed and compared for the use of both glass fibre and polycarbonate filters during sample collection. Ion suppression was shown to be a significant cause of reduced instrument response to N-osmolytes and was associated with the presence of seawater in the sample matrix.

Antarctic sea ice region as a source of biogenic organic nitrogen in aerosols

“…Glycine betaine and choline were extracted from filters into 15 mL 12:5:1 methanol:chloroform:water containing internal standard (d 11 -glycine betaine) by soaking (1 hr). Solutions were clarified by centrifugation and analysed by LC/MS 52 . To calculate the proportion of POC contributed by DMSP or the N-osmolytes, their concentration in nmol L −1 was multiplied by 5 to account for 5 C atoms per molecule, and divided by 1000 and by the POC concentration in µmolC L −1 .…”

Aliphatic amines at the Cape Verde Atmospheric Observatory: Abundance, origins and sea-air fluxes

“…They are released via direct emission from phytoplankton as well as via degradation of organic matter that contains proteins, amino acids or other nitrogenbearing compounds (King, 1988). Additionally, biological degradation of quaternary nitrogen osmolytes (R4N + , where R is an alkyl substituent on the N atom) is proposed as a major source of methylamines in seawater (Beale and Airs, 2016). These osmolytes, such as glycine betaine (GBT), trimethylamine N-oxide (TMAO) and choline are produced by marine organisms to maintain osmotic pressure (Burg and Ferraris, 2008).…”

Electromembrane Extraction of Highly Polar Compounds: Analysis of Cardiovascular Biomarkers in Plasma

“…Due to their very low lipophilicity, these highly polar molecules are difficult to extract using conventional sample preparation methods such as solid-phase extraction or reversed-phase SPE [9], which are based on the partition coefficients of analytes in two-phase systems. Indeed, only PP has been reported as efficient sample pre-treatment for these class metabolites so far [31,32]. PP is typically used in metabolomics, especially in large-scale studies where high throughput is essential.…”