FIG 1.
How SeaMet works. (A) Modifications to the standard two-step methoximation (MeOX)- trimethylsilylation (TMS) derivatization protocol include key steps that enhance metabolite signal detection in seawater as shown in panel B. Steps modified from the standard method include a switch in derivatization reagents from MSTFA to BSTFA, removal of water azeotropically by the addition of toluene (TOL) to the salt pellet and subsequent removal under N2 gas, ultrasonication (SON) after the addition of TOL, MeOX, BSTFA, and after BSTFA derivatization, and drying (DRY) of the pyridine after the MeOX derivatization prior to BSTFA addition. (B) Box plots showing changes in total ion chromatogram (TIC) signals of a metabolite mixture after GC-MS data acquisition. The results are from a mixture of 45 metabolites representing a broad scope of metabolite classes (Table S1) dissolved in 0.5 ml of seawater (n = 5) relative to the average of the no-salt control. (C) Box plots showing increases in peak areas of individual metabolites relative to the no-salt control for lauric acid, thymine, fructose, and sucrose.