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

Rachael Beale; Ruth Airs

doi:10.1016/j.aca.2016.07.016

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

Anal Chim Acta. 2016 Sep 28:938:114-22. doi: 10.1016/j.aca.2016.07.016. Epub 2016 Jul 25.

Authors

Rachael Beale¹, Ruth Airs²

Affiliations

¹ Plymouth Marine Laboratory, Plymouth, Devon, PL1 3DH, England, United Kingdom. Electronic address: rbea@pml.ac.uk.
² Plymouth Marine Laboratory, Plymouth, Devon, PL1 3DH, England, United Kingdom. Electronic address: ruai@pml.ac.uk.

PMID: 27619093
DOI: 10.1016/j.aca.2016.07.016

Abstract

A 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.

Keywords: Choline; Glycine betaine; Liquid chromatography mass spectrometry; Nitrogenous osmolytes; Seawater particulate analysis; Trimethylamine N-oxide.