Nontargeted analysis of the urine nonpolar sulfateome: a pathway to the nonpolar xenobiotic exposome.

Rationale: Testing the urine nonpolar sulfateome can enable discovery of xenobiotics that are most likely to be bioactive. This is based on the fact that nonpolar xenobiotics are more likely to enter cells where they tend to undergo metabolism, in part, to sulfates that are then largely excreted into the urine.

Methods: The following sequence of steps, with conditions that achieve high reproducibility, was applied to large human urine samples: (1) competitive nonpolar extraction with a porous extraction paddle; (2) weak anion-exchange extraction with strong organic washing; and (3) ultrahigh-performance liquid chromatography (UHPLC)/negative ion matrix-assisted laser desorption ionization tandem time-of-flight mass spectrometery (MALDI-TOF/TOF-MS) with recording of ions with signal-to-noise (S/N) ≥ 20 that yielded M-1-80 (loss of SO ) or m/z 97 (HSO ) upon fragmentation.