Agilent 6540 uhd accurate mass

A UHPLC system (Agilent 1290) was interfaced with a quadrupole Time-Of-Flight (TOF) mass spectrometer detector (Agilent 6540 UHD Accurate-Mass, Agilent, Waldbronn, Germany), using an ESI interface, operating in both positive and negative ionization modes. The source operated at 325 °C and nitrogen was used as the drying gas, at 2.8 bar, as well as nebulizing gas at a flow of 10 L min⁻¹. The injection volume was 5 μL and the TOF-MS detector was set to acquire MS data over an m/z range of 100 to 1600. A capillary voltage of 4 kV was used in positive and 3 kV in negative ESI mode.
The separation was performed in a Waters analytical column BEH C₁₈ 100 × 2.1 mm, 1.7 μm particle size (Waters, Milford, MA, USA) at a flow rate of 200 μL min⁻¹. The column was thermostatically controlled at 40 °C and the mobile phase consisted of water with 0.1% formic acid (A) and methanol with 0.1% formic acid (B). A gradient program was applied, starting from 50% B changed linearly to 95% B at 25 min followed by an isocratic elution for 4 min (t = 29 min). An equilibration of 1 min was set for the mobile phase to reach initial conditions.
An MS/MS fragmentation experiment was performed based on the precursor ion (m/z) of each of the isolated cyclic PBT oligomers. The optimum collision energy (eV) for each of the target analytes was optimized, performing experiments ranging from 0 to 100 eV.

A UHPLC system (Agilent 1290) with a qTOF-MS (Agilent 6540 UHD Accurate-Mass, Agilent, Waldbronn, Germany), with ESI+ (4 kV) and ESI- (−3 kV) ionization modes, were used. The source temperature was 325 °C. Nitrogen was used as both the drying (40 psi) and nebulizing gas (10 L min-1). The injection volume was 5 μL. The TOF-MS detector was set for a m/z range of 100–1600, with acquisition of MS/MS high resolution accurate mass data. The fragmentation collision energies for the ESI (+) ranged from 5–60 eV.
A Waters (Waters, Milford, MA, USA) BEH C18 (100 × 2.1 mm, 1.7 μm) analytical column was used at 40 °C. The mobile phase (flow rate: 200 μL min⁻¹) consisted of water (A) and methanol (B), both with 0.1% formic acid. The gradient program changed linearly from 50% to 95% (B) in 25 min, followed by an isocratic elution for 4 min and an equilibration time of 1 min to reach initial mobile phase conditions.
Thermo LTQ Orbitrap MS (Thermo Scientific, Bremen, Germany). Analysis was performed with ESI+ operated with mass resolution of 140,000 at m/z 400. The chloroform extracts of the herbal material were first diluted in pure acetonitrile, followed by another dilution with H₂O to have a final 1:1 v/v ratio. The resulting samples were then infused at a flow rate of 5 μL/min on the system.