2.6.2. Bioamine Detection via UPLC-QQQ-MS/MS

To detect the changes of bioamines in mice serum, 50 μL serum was mixed with 200 μL methanol, and then centrifuged at 13,000 g for 15 min. The supernatant was filtered with a nylon membrane (22 μm). Samples were separated using an Agilent 1290 Infinity II series UPLC system equipped with an Agilent Zobax Eclipse C18 Rapid Resolution HD column (2.1 mm × 100 mm, 1.8 μm). Mobile phases A and B were water (containing 2 mM ammonium formate and 0.1% *v*/*v* formic acid) and methanol, respectively. The gradient was set as follows: 1 min, 2% B; 4 min, 15% B; 4.5 min, 98% B; 6 min, 98% B; 6.1 min, 2% B; post time 3 min, 5% B. An Agilent 6470 ESI-QQQ system was adopted for MS acquisition. Mass spectrometry parameters were set as follows: 250 ◦C, gas temperature; 7 L/min, drying gas flow rate; 30 psi, nebulizer pressure; 325 ◦C, sheath gas temperature; 11 L/min sheath gas flow rate. The precursor ion, product ion, collision energy and fragmentor are listed in Table S1 in Supplementary Materials.
