ton. To collect the remaning sufonics ~ndividually, we then renlected the sufoncs n t o the C , which was equpped ~511th a 10 m by 100 lnln Phenomenex (Torrance. CA) star-ion anon exchange column, and eluted them twth a 5.4 m M Na,CO, + 5.1 mM NaHCO, buffer, l?le separated ESA f r o~n a small amount o4 co-eutng sulfate by reinjecting the ti~!o compounds and eluting them with a 3.2 m M Na,CO, + 3 1 NaHCO, m M buffer. Basene separation between MSA and ESNsulfate vias -2 min; betvieen ESA. sulfate and i?SA, t vias -9 min, and between ESA and sulfate, it vias -1 min. Ater re-~noval of the carbonate buffer with HCI, each compound twas then placed n a quanz tube and dred by rotary evaporation (maxmu~n temperature -50'C).Copper oxde was then placed :n each tube, and h:gh vacuum, with m~lo warmin9 (<10S3C), was used for co~npete drying. The sa~nples v/ere then sealed and combusted to sulfate, CO,, an0 H, O at 500'C. The CO, and H 2 0 were collected w~t h a proced~re smiar to that of Epsten et a1 (73). The H, O vias con\!ened to H by the method of Cole~nan and Moore (27) viith a znc catalyze f r o~n J. M. Hayes of Indiana Unversit),. The CO, and H were then analyzed w~t h 6-60-Nuclide and 3-60-HD-Nuclide mass spectrometers. The sulfate vias extracted from each tube with hydrochorc acid an0 prepared for S isotopic analysis as in (6).
