Location: Samples were collected in June 2019 on the R/V Atlantic Explorer from the Bermuda Atlantic Times Series (BATS) station and nearby stations at 31 50'N, 64 10'W from the upper 1000m.

Cruise or Deployment:

Samples were collected from the RV Atlantic Explorer (cruise V-1912 BATS/HYDRO/GRUNDLE) from June 5-11. Chief Scientist, Rod Johnson.

Methods & Sampling:
10 L samples were collected in June 2019 on the R/V Atlantic Explorer from the Bermuda Atlantic Times Series (BATS) station at 31 50'N, 64 10'W. Samples were pumped through polyethersulfone filters (Millipore Millex GP 0.2 µm, 25 mm) and then solid phase extracted onto 1 g polystyrene divinylbenzene resin columns (ENV, Agilent). Columns were preconditioned by sequentially rinsing with 6 mL LCMS grade methanol, 6 mL pH 2 ultrapure water (acidified with trace metal grade HCl), and 6 mL of ultrapure water prior to sample loading. A process blank sample was prepared by priming and rinsing an SPE column without sample loading. After sample loading, the columns were rinsed with 6 mL ultrapure water and stored frozen at –20 °C. Immediately prior to analysis, columns were thawed, rinsed again with 5mL ultrapure water, and eluted with 6mL of methanol. Samples were concentrated in a vacuum centrifuge to a volume below 0.5 mL until only residual water remained, and then samples were all brought up to a final volume of 0.8 mL with ultrapure water. An internal standard of cyanocobalamin was added to each sample (3 µM final concentration). Pooled quality control samples were prepared by combining 20 µL of each sample and were analyzed periodically throughout the sample batch in order to rule out significant drift in retention times or sensitivity.

Instruments:

Samples were analyzed by 21 Tesla Fourier Transform Ion Cyclotron Resonance Mass Spectrometer coupled to a microflow high pressure chromatography system (Ultimate 3000 RSLCnano, Thermo Scientific). The 21 T FT-ICR MS was designed and built in the Environmental Molecular Sciences Laboratory at the Pacific Northwest National Laboratory 26. The ESIMS was equipped with a heated electrospray ionization source set to a capillary voltage of 3200 V, sheath, auxiliary, and sweep gas flow rates of 15, 3, and 1 (arbitrary units), ion transfer tube temperature of 300°C, vaporizer temperature of 75°C. Mass spectra were collected with 1.5 second transients with a maximum ion accumulation time of 250 ms in positive ionization mode.