“…LC conditions were as follows: mobile phase A: 95% aqueous 2 mmol/L formic acid, pH 3.5 adjusted by ammonium hydroxide, 5% acetonitrile; mobile phase B: 100% acetonitrile; flow rate: 0.5 mL/min; gradient, 0 to 1 min, 70% A; 1 to 3.5 min, 70% to 30% A; 3.5 to 4.5 min, 30% to 70% A, 6-min equilibration at 70% A; and column: Phenomenex C 18 , 150 Â 3 mm, 3 Am, at 45jC. MS/MS conditions were as follows: Applied Biosystems 3200 Q-Trap instrument, in multiple reaction monitoring mode, m/z 472/221 (PBOX-H + - 35 Cl, 35 Cl), m/z 480/229 (PBOX-d 4 -H + - 37 Cl, 37 Cl); curtain gas 40 p.s.i. ; ion spray voltage, 5,500 V; temperature, 300jC; ion source gas 1, 40 p.s.i.…”