A Validated Stability-Indicating RP-HPLC Method for the Simultaneous Determination of Tenofovir, Emtricitabine, and a Efavirenz and Statistical Approach to Determine the Effect of Variables

Table 1

Fraction factorial design to assess method robustness.

Parameter					Retention time (min)			USP tailing
Buffer conc.	pH of; Mobile phase	Flow rate; (mL min^−1)	% B	Temp. (°C)	FTC	TDF	EFV	FTC	TDF	EFV
15	3.3	1.3	−2	30	2.4	5.4	8.2	0.94	0.97	0.98
15	3.3	1.7	2	25	1.6	4.5	7.2	0.97	0.99	0.88
15	3.7	1.3	2	25	1.9	5	7.7	0.89	1.09	0.9
15	3.7	1.7	−2	30	2	5	7.5	0.96	1.07	0.91
25	3.3	1.3	2	30	1.9	4.8	7.5	1	1.07	0.95
25	3.3	1.7	−2	25	1.8	4.8	7.3	0.87	1.02	0.89
25	3.7	1.3	−2	25	2.3	5.4	7.7	0.98	1.12	0.93
25	3.7	1.7	2	30	1.5	4.7	7.2	0.99	0.98	0.89