MS/MS for HgPC2 complex analysis
For LC-MSn measurements the same HPLC system described above is used, including chromatographic column and analysis conditions, but the MSn study was performed using a HCT Ultra high-capacity ion trap (Buker Daltonics). ESI conditions were as described previously and to establish the optimum MSn conditions, standard solutions of HgPC2 were tested. A volume of 20 µL of standard or xylem sap samples was injected into the LC system and MSn analysis were controlled by HyStar v 3.2 software (Bruker Daltonics). MSn experiments were conducted by selecting the high intensity peak mother ion (740.1m/z for MS, and 536.1 m/z for MS2) at the retention time of the compound chromatographic peak, and data were collected in total ion counting mode, acquiring the spectra in the range 100-1100 m/z .