Table 1 Instrument parameters

Mobile phase

Phase A: 0.1% formic acid aqueous solution

Phase B: 0.1% formic acid acetonitrile solution

Flow rate

0.35 mL/min

Column temperature

40 ℃

Injection volume

2 μL

Elution gradient

0.0 min A/B(90:10 V/V)

12.0 min A/B(10:90 V/V)

14.1 min A/B(90:10 V/V)

16.0 min A/B(90:10 V/V)

Mass spectrometric parameters

 Ion source

Electrospray ionization (ESI)

 Sheath gas

40 arb

 Auxiliary gas

10 arb

 Ion spray voltage

− 2800 V

 Temperature

350 ℃

 Ion transfer tube temperature

320 ℃

 Scan mode

Fullms-ms² Mode

 Ion mode

Negative Ion Mode

 Data processing software

TraceFinder