Preparation and Evaluation of Intravaginal Ring Containing Drospirenone

Table 2

The gradient elution process for HPLC of drospirenone.

𝑇 (min)	Water (%)	Acetonitrile (%)	Elution
0–28.5	64	36	isocratic
28.5–45	64–100	36–90	Linear gradient
45–45.5	10–0	90–100	Linear gradient
45.5–52	0	100	isocratic
52-53	0–64	100–36	Linear gradient
53–80	64	36	Reequilibration