Development and Validation of a Reversed-Phase HPLC Method for the Estimation of Zolpidem in Bulk Drug and Tablets

Table 4

Result of robustness study.

Factor	Level	Mean	% RSD
pH of mobile phase	6.3	5.03	0.4
	8.0	5.01	0.8
	9.67	5.06	0.3
Flow rate (mL/min)	0.5	5.10	0.6
	1.0	5.15	0.8
	1.5	5.12	0.2
	2.0	5.16	0.4
Column oven temperature (°C)	25	5.03	0.8
	35	5.07	0.1
	45	5.10	0.4
% acetonitrile	(55/45)	4.98	0.5
	(60/40)	5.01	0.3
Detection wavelength (nm)	241	5.01	0.4
	243	5.04	0.5
	245	5.11	0.2
	250	5.00	0.2