Table 1. Gradient condition of mobile phases for biotin analysis by HPLC

Time (min)	Flow rate (mL/min)	0.1% phosphoric acid (%)	100% acetonitrile (%)	80% acetonitrile (%)
0	0.6	90	10	0
18	0.6	90	10	0
21	0.6	0	0	100
26	0.6	0	0	100
29	0.6	90	10	0
32	0.6	90	10	0