Isq ec mass spectrometer

Samples analysis was performed using a system comprised of a UHPLC Vanquish pump, Vanquish Autosampler, Vanquish UHPLC + column compartment, and ISQ EC mass spectrometer (ThermoFisherSci.), in conjunction with ThermoFisherScientificDionexChromeleon 7 Chromatography Data System software. A C18 column (4.6 mm ID X 100 mm L, 5 µm, 120 Å; Acclaim 120; ThermoFisherSci.) was used with a 0.25 mL/min. flow rate and 0.5 µL injection volume; the autosampler needle was washed with 10% (v/v) methanol (10 s) after each sample injection. Mobile phases A and B consisted of 10 mM ammonium acetate and LC-MS grade acetonitrile, respectively. The linear gradient mobile phase flow was characterized by an increase in acetonitrile from 50% to 80% between 0 to 4 min, followed by a decrease to 50% between 4 to 8 or 15 min. Preliminary results guided selection of the following mass spectrometric parameters: vaporizer temperature (VT) = 250 °C; ion transfer tube temperature (ITT) = 200 °C; optimum sheath gas pressure (SGP) = 25 psig; auxiliary gas pressure (AGP) = 2 psig; sweep gas pressure (SWGP) = 0.5 psig; and negative mode, which resulted in an extracted Gln-FMOC chromatogram at m/z 367.1. Column and autosampler temperatures were maintained at 35 °C and 15 °C, respectively. This method represented here as Gen-MS-I.

LC–MS analyses were performed by an Ultimate 3000 UHPLC instrument coupled with an ISQ EC mass spectrometer, equipped with an electrospray ion source and a single-quadrupole analyzer (Thermo Fisher Scientific, Cambridge, MA, USA). A C18, Luna® Phenomenex, 5 µm 100 Å (150 × 4.6 mm) (Phenomenex, Torrence, CA, USA) was used for chromatographic separation. The mobile phase was composed of solvents A (Water, 0.1% HCOOH) and B (Acetonitrile, 0.1% HCOOH). An isocratic mode (30:70) was used. The flow rate was set at 0.2 mL/min and the column was maintained at 30 °C for the entire run. Fifty microliters were injected. Analyses were performed using the positive ionization mode selecting the following m/z: 91, 137, 154, 369. The collision energy (CE) was 20 eV. Mass spectrometry parameters were: spray voltage (V) 3000, sheet gas (arb) 28.8 psig, aux gas (arb) 3.2 psig, ion transfer tube temperature 300 °C, and vaporizer temp 117 °C. Peak areas were measured by using the Chromeleon software (Thermo Fisher Scientific).