4.6.3. Apparatus and Analytical Conditions

The HPLC separation was performed by an Agilent 1260 Infinity II series HPLC System that was equipped with Waters Atlantis C18 column (150 × 3.9 mm, 5 μm). The mobile phase consisted of solvent A (water containing 0.1% formic acid) and solvent B (methanol). The gradient procedure was as follows: 0–3 min 60–5% A, 3–5 min 5–5% A, 5–5.02 min 5–60% A, and 5.02–6 min 60–60% A. The flow rate was 0.5 mL/min and the injection volume was 5 μL.

An Applied Biosystems Sciex QTRAP®4500 MS/MS spectrometer equipped with a version of 1.6 Analyst software (AB SCIEX, Massachusetts, USA) was used for the analysis. The instrument was equipped with an ESI source, and the targeted analytes were performed in positive and negative ion modes for all the targeted analytes. Compressed air was used as GS1 and GS2, and high-purity (99.99%) nitrogen was used as CUR and CAD. The operation conditions were as follows: the EP was 10.0/−10.0 V, the TEM at 500 ◦C, the IS 5500/–4500 V, GS1 set to 55 psi, GS2 set to 55 psi, CUR set to 35 psi, and the CXP 13.0/−15.0 V for ESI+/ESI<sup>−</sup> mode, respectively. The dwell time for each MRM transition was 10 ms.
