Thermo ltq orbitrap xl

To identify the intermediates in PMS activated by DMBQ, DCBQ and TFBQ, in situ analysis and real-time monitoring of the reaction of PMS and quinones were carried out by droplet spray ionization mass spectrometry (DSI-MS). A detailed description of DSI-MS is given elsewhere.^{22,24 (link)} A photograph of the DSI-MS is shown in Fig. S1.† The protocol for in situ analysis and real-time monitoring of PMS activated by different quinones involved three steps (Fig. S2†). Firstly, 10 μL of methanol/water (v/v: 7/3) was loaded onto the corner at 0 s. When a high voltage of −4 kV was applied to the solution, an electrospray was formed between the corner and the MS inlet. Then, 10 μL of different quinones (DMBQ, TCBQ, and TFBQ) (5 × 10⁻⁵ mol L⁻¹) was loaded onto the corner at 10 s. Finally, 30 μL of PMS (5 × 10⁻⁴ mol L⁻¹) was loaded onto the corner at 14 s. Data were recorded continuously during these additions of reagents. The sample solutions were adjusted at pH 10 before pipetting to the corner. These experiments were implemented on a Thermo LTQ-Orbitrap XL mass spectrometer (Thermo Fisher Scientific, Waltham, MA, USA). The operation parameters were set as follows: resolution, 60 000; capillary temperature, 275 °C; ion maximum injection time, 500 ms; tube lens voltage, −110 V; capillary voltage, −35 V.

The online elution interface in AIMS analysis is schematically presented in Fig. 1B. A 500 μL Hamilton syringe (Bonaduz, Switzerland) was filled with methanol containing 0.1% (V/V) formic acid, which acted as the eluent and ionizing medium. The syringe pump installed in the MS pumped the methanolic solution at 30 μL/min through a polyether ether ketone tube that was already connected to the N6-Cel-HN by a precut 10 μL pipette tip that acted as an adapter. An electric clamp was connected to the HN, leaving 25 mm between the clamp and the tip of the needle to ensure the mechanical stability of the ESI emitter. The distance between the HN tip and the MS inlet was fixed at 10 mm to prevent electric discharges. The eluent flowed through the N6-Cel sorbent, eluting the analyte that was finally electrosprayed in the tip of the HN.
High-resolution AIMS analyses were carried out in a Thermo LTQ Orbitrap XL hybrid mass spectrometer (Thermo Fisher Scientific Inc., San Francisco, CA, USA), working with the Fourier-transform mass spectrometry analyzer. The ionization parameters of the proposed interface are presented in the Supplementary data.