Urinary nucleosides as biological markers for patients with colorectal cancer

Table 2 Time events for the switching of column and of mobile phase¹

Time (min)	Pump	Event	Valve position
0.00 – 7.00	Pump 1 (eluent A)	Sample matrix are discharged by column 1	1
	Pump 2 (eluent B)	Conditioning of column 2
7.00 – 10.00	Pump 2 (eluent B)	Analytes are transferred from column 1 to column 2	2
10.00 – 50.00	Pump 2 and Pump 3 (eluents B and C)	Analysis of nucleosides on column 2 by using a linear	1
		gradient elution program
	Pump 1 (eluent A)	Conditioning of column	1

¹Eluent A: 0.25 mol/L NH₄AC (pH 8.5); eluent B: 25 mmol/L KH₂PO₄ (pH 4.5); eluent C: methanol:water (3:2, v/v). Flow rate: pump 1, 0.2 mL/min; pump 2, 1.2 mL/min. Detection wavelength: 260 nm.