Abstract:

This dataset contains mass spectrometer analyses of porewater collected from Baffin Bay, Texas obtained from 2020-10-01 to 2021-10-01. Sample preparation was by solid phase extraction cartridges while dissolved organic matter samples were analyzed with a Vanquish Ultra Pressure Liquid Chromatography – Orbitrap Fusion Tribrid Mass Spectrometer (UPLC-OT-FT-MS).

Suggested Citation:

Abdulla, Hussain. 2024. Mass spectrometer analyses of porewater collected from Baffin Bay, Texas obtained from 2020-10-01 to 2021-10-01. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/dz59wkcc

Purpose:

Identifying different dissolved organic nitrogen (DON) that accumulated in Baffin Bay, Texas sediment.

Data Parameters and Units:

NO. (sample number), Name, Formula, Calc. MW (molecular weight), RT [min], Type, Porewater (PW), Nepheloid layer (NL), Depth (in cm), season (date), Station, latitude, longitude.

Methods:

Samples were prepared for mass spectral analysis using PPL solid phase extraction cartridges (Agilent, Bond Elut PPL, 100 mg resin, 3 mL volume (Dittmar et al., 2008). A liquate of 10 mL of filtered porewater samples was acidified using trace metal grade hydrochloric acid (HCl) to pH 2. The samples were extracted using 200 mg, 3mL Bond elute-PPL cartridges. Blank Milli-q water was extracted as a sample. Final DOM extracts were eluted using 6 mL HPLC Optima grade methanol and collected in pre-combusted glass vials. (Dittmar et al 2008; Stucheli et al., 2018). Final SPE-DOM extracts were dried using a Centrivap benchtop concentrator and diluted to 1 mL Milli-q water. The samples were analyzed with both UPLC-OT-FTMS (positive mode) and IC-OT-FTMS (negative mode) according to (Bergmann et al., in preparation). Liquid Chromatography-Orbitrap Fusion Mass Spectrometer DOM extracted samples were analyzed for positive mode detection analysis by Vanquish Ultra Pressure Liquid Chromatography – Orbitrap Fusion Tribrid Mass Spectrometer (UPLC-OT-FT-MS). The analytes were separated on the 1.7 μm ACQUITY UPLC BEH C18 reversed-phase column by Waters (130 Å, 1.7 μm, 2.1 mm × 150 mm) and guided to a heated electrospray (H-ESI) and the Orbitrap Fusion Tribrid Mass Spectrometer. The injection volume of each sample was 20 μL. The Eluent A, Milli-Q with 0.1 % (v/v) formic acid, and eluent B, acetonitrile with 0.1 % (v/v) formic acid, were mixed with curve 5 to a flow rate of 0.200 mL/min. The total run lasted 31 min with 7 min re-equilibration and the following gradient: 0-2 min hold at 5 % B, ramp to 65 % B for 18 min, then ramp to 100 % B for 1 min and hold at 100 % B for 3 min. The H-ESI setting was 3500V for the positive spray voltage with ion transfer tube temperature at 300 °C and vaporization temperate at 225 °C. The three gases on the H-ESI were 35 for sheath gas, 7 for aux gas, and 0 for sweep gas. The OT-FT-MS was set at 500,000 (FWHM at m/z 200) resolution and mass range 80-800 m/z with RF lens at 40%. Two MS2 were scanned with the Ion Trap following the full scan via two filters, Dynamic Exclusion (n = 1 for 30s) and Intensity Threshold (min = 5000, max = 1.0e20). Both MS2 scans were isolated via the Quadrupole with a mass bandpass of 0.7 m/z, but one fragmentation scan was generated using collision-induced dissociation (CID) with assisted energy collision, and the other fragmentation scan was generated with higher-energy collisional dissociation (HCD) with stepped energy collision. Both MS2 scans had an automatic gain control (AGC) set at 1.0e4 and a maximum injection time of 50 msec. The locking solution was introduced to the sample via a t-shaped connection after the column separation of analytes and before H-ESI. A flow-regulated peristaltic pump assured a continuous but consistent mixing of internal standards with the sample at a flow rate of 0.05 mL/min. The selected standards had masses of 94.0621, 122.0844, 139.1191, and 207.0912 m/z added to the list (max. 8 compounds). This setting instructed the OT-FT-MS to look specifically for these four compounds, choose the standard with the highest intensity and perform an on-the-fly internal calibration for each scan.

Provenance and Historical References:

Dittmar Thorsten, Koch Boris, Hertkorn Norbert, Kattner Gerhard (2008) A simple and efficient method for the solid-phase extraction of dissolved organic matter (SPE-DOM) from seawater, Limnol. Oceanogr. Methods, 6, doi:10.4319/lom.2008.6.230. Stücheli, Patrick & Niggemann, Jutta & Schubert, Carsten. (2018). Comparison of different solid phase extraction sorbents for the qualitative assessment of dissolved organic nitrogen in freshwater samples using FT-ICR-MS. Journal of Limnology. 77. 10.4081/jlimnol.2018.1791.

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