Phosphorus (P) is an essential nutrient for all forms of life. In the ocean, organic phosphorus is a large pool of P in surface waters sustaining the marine microbial community by meeting their P demands. Thus, when studying the marine biogeochemical P cycle, characterizing this pool is of great interest but currently limited by the lack of appropriate methods. So far, most P metabolites analyses use targeted metabolomics and have only been occasionally applied to marine samples. Marine untargeted metabolomics using liquid chromatography coupled with electrospray ionization (HPLC-ESIMS) is now well established in the field of metabolomics and has helped identify many key metabolites especially new nitrogen and sulfur metabolites. However, P metabolites remain under-characterized due to the poor ionization efficiency of P compounds, their poor retention on solid phase extraction columns (due to their high polarity), and their lack of stable isotope which prevents the use of mass search algorithms that target natural abundance isotope ratios of specific heteroatom (S, Br, Fe, Cu, etc.). To increase our knowledge of the molecular composition of marine P metabolites, we developed an HPLC-ESIMS/MS phosphorus targeted-approach based on a multiple reaction monitoring precursor-product ion method. We applied this method to DOM and POM samples and were able to characterize several new P metabolites including phosphonates which gives further evidence of the existence of a P redox cycling in the ocean.

Primary Presenter: Marianne Acker, Scripps Institution of Oceanography (maacker@ucsd.edu)

Authors:

Matthew McIlvin, WHOI  (mmcilvin@whoi.edu)

Alina Ebling,   (aebli1987@gmail.com)

Benjamin Van Mooy, WHOI  (bvanmooy@whoi.edu)

Mak Saito, WHOI  ()

Daniel Repeta, WHOI  (drepeta@whoi.edu)