Table 1.

UPLC-MS/MS column and binary solvent gradient conditions.

Column	Waters UPLC Acquity BEH C18 Column (1.7 µm, 2.1 ×100 mm)
Column temp. (°C)	28
Sample temp. (°C)	10
Solvent A	1 mM ammonium formate and 0.1 % formic acid in 95 % water/5 % acetonitrile
Solvent B	1 mM ammonium formate and 0.1 % formic acid in 5 % water/95 % acetonitrile
Time (min)	0	1	2	2.15	2.5
Solvent B (%)	75	98	98	75	75
Total run time (min)	2.5
Injection volume (µL)	2
Flow rate	0.35 mL/min
PBO Retention Time	1.8 min