Fig. 2. Capture efficiency and analysis of the conjugated thiols. (a) Reactivity of simplified probe 2 with thiols T1–T20. Reaction conditions: (i) 2, thiol (T1–T20), Et3N, DMF or K2CO3, and DMF/H2O (1 : 1); (ii) TFA. (b) Representative mass spectrometric extracted ion chromatograms of 7 selected thiol conjugates that were successfully captured (TCP3, TCP4, TCP5, TCP7, TCP13, TCP14, and TCP18) after treatment with 2. Conditions: Et3N in DMF at 28 °C for 16 h. (c) Stability of two Boc-deprotected thiol conjugates [TC5 (glutathione) and TC7 (2,3,10-mercaptopinane)] after Pd(0) treatment at 25 °C for 18 h. Top: extracted ion chromatograms (EICs) of the corresponding thiol conjugate before Pd(0) treatment. Bottom: unchanged EICs after Pd(0) treatment. (d) EICs of the LOD measurements comparing 1-butanethiol with conjugated 1-butanethiol. (e) MS/MS fragmentation of the thiol glutathione conjugate TC5 with CID (30–75 eV).
