Agilent 6120 single quad ms system

The AA analysis was performed with an Agilent 1260 Infinity II LC-MS system coupled to an Agilent 6120 Single-Quad MS system (Agilent Technologies Inc., Santa Clara, CA, USA) with an electrospray-type ionization source. The column of the LC-MS system used was a Resiek Ultra AQ C18 column (3 µm, 100 mm × 2.1 mm) (Bellefonte, PA, USA).
The sample was separated by the mobile phase (aqueous 0.2% acetic acid and 1% methanol) for 7 min at 0.200 mL/min with a 10 µL injection volume after 1 min post-time to equilibrate the column. The column oven temperature was set at 35 °C and the electrospray was operated in positive ion mode. The conditions used in the ionization source were: 250 °C at 12.0 L/min for the drying gas (N₂), a nebulizer pressure of 35 psig, and a capillary voltage of 3000 V. AA was determined using the Selective Ion Monitoring mode (SIM), monitoring the ions m/z 72.0 for AA and 75.0 for ¹³C₃-AA (internal standard).
By using a five-point calibration curve, the concentrations of AA in the control and samples were determined and then the percentage of AA reduction was obtained using the following equation: $$\mathrm{AA}\mathrm{reduction}(\%)=\frac{Conc.ofAAincontrol\left(PBS\right)-Conc.ofAAinsample}{Conc.ofAAincontrol\left(PBS\right)}$$

The AA analysis was performed with an Agilent 1260 Infinity II HPLC system coupled to an Agilent 6120 Single Quad MS system (Agilent Technologies Inc., Santa Clara, CA, USA) with an electrospray type ionization source. The column of the HPLC system used was a Restek Ultra AQ C18 column (3 μm, 100 × 2.1 mm) (Bellefonte, PA, USA). The sample was separated by the mobile phase (aqueous 0.2% acetic acid and 1% methanol) for 7 min at 0.200 mL/min with 1 min post-time to equilibrate the column [9 (link)]. The sample injection volume was 10 μL. The column oven temperature was set at 35 °C. The electrospray was operated in positive ion mode. The conditions used in the ionization source were: 250 °C at 12.0 L/min for the drying gas (N₂), a nebulizer pressure of 35 psig and a capillary voltage of 3000 V. AA was determined using the Selective Ion Monitoring mode (SIM), monitoring the ions m/z 72.0 for AA and 75.0 for ¹³C₃-AA (internal standard).
By using a five-point calibration curve, the concentration of AA in control and samples were determined and then the percentage of AA reduction was obtained using the following equation.
$$AA reduction (\%)=\frac{Conc. of AA in control \left(PBS\right)-Conc. of AA in sample}{Conc. of AA in control \left(PBS\right)}\%$$