Measurement of methylamines in seawater using solid phase microextraction and gas chromatography

Abstract

The methylamines form part of the marine organic nitrogen pool. Although they are ubiquitous in marine systems, little is known about their distribution, production, and fate in the marine environment. Analytical methods have been developed for their analysis in marine waters, but these have employed custom‐made apparatus, limiting data to a few studies. Here, we report a method developed for the determination of methylamines in seawater which combines headspace solid phase microextraction (SPME) and gas chromatography with selective nitrogen detection. Gaseous methylamines were pre‐concentrated from water samples (∼ 1 L) heated to 60 °C, onto a polydimethylsiloxane/divinylbenzene SPME fiber located in the headspace of the extraction flask. The analytes were then thermally desorbed from the fiber in a gas chromatograph containing a CP‐Volamine column and a nitrogen–phosphorus detector. The method was routinely calibrated down to 1 nM for all three analytes using matrix‐matched external standards. Limits of detection were determined operationally and ranged from 0.4 nM to 2.9 nM during two sampling campaigns. The analytes were detected in seawater samples from the English Channel and Southern Ocean where concentrations up to 20 nM and 5.6 nM were measured, respectively, consistent with previously reported levels. We propose this method for the analysis of methylamines, and other low‐molecular weight amines, as it is sensitive, robust, and the necessary equipment is widely available.

Simultaneous Detection of Alkylamines in the Surface Ocean and Atmosphere of the Antarctic Sympagic Environment

“…Briefly, the ART-2a area matrix (AM) of a single particle mass spectra reppresents the average intensity for each m/z for all particles within a group, reflecting the typical mass spectra of specific aerosol groups. (mono-, di-and trymethylamines) were extracted from the water sample by solid phase microextraction 34 , where polydimethylsiloxane/divinylbenzene fibre was exposed in the headspace above the water sample, for 2.5 h at 60 o C. Methylamines were resolved and detected using a GC with NP detector, calibrations carried out using external matrix-matched standard solutions containing mono-, di-and trimethylamine (0.13-13.3 nM).…”

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

“…Further analyses of water samples were performed at the University of Plymouth, UK, using solid phase microextraction, gas chromatogpaphy and nitrogen phosphorous detection (SPME-GC-NPD) according to Cree et al, (2018). In brief, 850 mL of the acidified filtered sample was adjusted to pH 13.4 with sodium hydroxide solution (10 M) to convert the amines to their gaseous form.…”

“…Cree (2014) found that 7 of 10 primary pigments also correlated positively with GBT, including fucoxanthin, while a close relationship of both GBT and chl-a with phytoplankton carbon was observed. Although bacteria may be the primary source of methylamines in the water column (Lidbury et al, 2014;Lidbury et al, 2015a;2015b;Jameson et al, 2016), their short residence time (Cree et al, 2018) indicates that both phytoplankton and bacteria play a role in methylamine abundance and dynamics.…”

Microbial trimethylamine metabolism in marine environments

“…More recently, Cree et al reported another method to determine dissolved methylated amines in seawater samples. Methylated amines converted to the gaseous phase were analysed by coupling headspace solid phase microextraction (SPME) and gas chromatography coupled with a nitrogen-phosphorus detector (GC-NPD) (Cree et al, 2018). This method provides lower detection limits and is more suitable for measuring methylated amines at low-nM level in marine environments.…”