Table 1.

LC gradient programme.

Time (min)	% solvent A	% solvent B	Flow (μL/min)
0	100	0	500
0.8	100	0	500
1.0	0	100	500
2.2	0	100	500
2.3	0	100	1000
3.0	0	100	1000
3.1	100	0	1000
4.6	100	0	750
4.7	100	0	500
5.1	100	0	500

Solvent A: acetonitrile–aqueous ammonium acetate 10 mM pH 3.5 (50–50, v/v). Solvent B: methanol–acetonitrile (75–25, v/v).