FIG. 1.

HPLC-ESI⁺-MS analysis of latex degradation products formed by reaction with RoxA in ¹⁶O₂ (A) and ¹⁸O₂ (B, C) atmospheres. (A) RoxA was incubated with latex for 3 h at 40°C, pH 7.0, in a ¹⁶O₂ atmosphere and in H₂¹⁶O buffer. Degradation products were extracted with ethyl acetate, dried, evaporated, dissolved in methanol, and loaded onto a C₈ reverse-phase HPLC column. The eluate was monitored by ESI⁺-MS, and the figure shows the average mass spectrum summed across the 14.8-min peak representing ODTD (eight scans). (B) The same experiment as described for panel A was performed, except that the reaction was carried out in an ¹⁸O₂ atmosphere and in H₂¹⁶O. (C) Enlargement of panel B around m/z 239. Arrows in the enlargement indicate the respective ¹³C isotope ions.