Luna omega lc column

SWATH-MS data for both female and male saliva samples were acquired on the same MS instrument used for LC–MS/MS. The liquid chromatography conditions were as follows. A volume of 5 µl of each digested sample was loaded onto a trap column (12-nm, 3-µ Triart C18, 0.5 × 5.0-mm LC column; YMC) and desalted with 0.1% TFA at 10 µl/min for 5 min. The peptides were then loaded onto an analytical column (3-µm polar C18, 150 × 0.3-mm, Luna OMEGA LC column; Phenomenex) equilibrated with 3% ACN and 0.1% FA. Peptide elution was performed with a linear gradient of 3–35% B in A for 45 min (A, 0.1% FA; B, ACN, 0.1% FA) at a flow rate of 300 nl/min.
The samples were acquired in a random order to avoid bias in the analysis. The samples were ionized in a source type Optiflow 1–50 µL micro, applying 4.5 kV to the spray emitter, and the analysis was carried out in DIA mode. Survey MS1 scans were acquired from 400 to 1250 m/z for 250 ms, and 100 variable windows from 400 to 1250 m/z were acquired throughout the experiment. The total cycle time was 2.79 s. The quadrupole resolution was set to UNIT for the MS2 experiments, and data were acquired from 100 to 1500 m/z for 25 ms in high sensitivity mode.

A method to determine NAC loading was developed for LCMS. Our LC (Agilent 1100 series) is equipped with a mass spectrometer and a Luna Omega LC column (Phenomenex, 100 × 4.6 mm, 3 μm, Polar C18 100 Å) was used for reverse-phase chromatography. LC eluents were solution A: DI-water (formic acid 0.1%) and solution B: acetonitrile under gradient elution (Table S1, ESI†). The flow rate was 0.3 mL min⁻¹ and injection volume was 10 μL. The column temperature was maintained at room temperature and the overall run time of each sample was 12 minutes. The mass spectrometer (Finnigan LTQ mass spectrometer) equipped with an electrospray interface (ESI) in positive electrospray ionization mode was used for the mass spectral data acquisition of NAC. The optimized parameters are sheath gas flow rate at 20 arbitrary units, spray voltage set at 4.00 kV, the capillary temperature at 350 °C, capillary voltage at 41.0 V, and tube lens voltage set at 125.0 V. The NAC calibration curve is provided in ESI (Fig. S2†).