Online Solid-Phase Extraction LC-MS/MS: A Rapid and Valid Method for the Determination of Perfluorinated Compounds at Sub ng·L⁻¹ Level in Natural Water

Table 1

Elution conditions employed in SPE online column.

Time (min)	Total flow (mL·min^−1)	% eluent A1 water 0.5% of NH4OH	% eluent B1 methanol 0.5% of NH4OH	Valve
0.0	0.8	50	50	A: exhaust
3.5	0.8	50	50	B: mass instrument
6.5	0.8	0	100	B: mass instrument
8.0	0.8	0	100	B: mass instrument
8.5	0.8	0	100	B: mass instrument
8.6	0.8	50	50	B: mass instrument
9.5	0.8	50	50	B: mass instrument
10	0.8	50	50	B: mass instrument
12	End			A: exhaust