Development and Validation of a Stability Indicating RP-HPLC Method for the Determination of Two Sun Protection Factors (Koptrizon and Tinosorb S) in Topical Pharmaceutical Formulations Using Experimental Designs

Table 1

System suitability results (precision, intermediate precision, and robustness).

Parameter	Theoretical plates for KPT > 2000	Tailing factor for KPT ≤ 2.0	% RSD* of standard Area (KPT) ≤ 2.0	Theoretical plates for TIN > 3000	Tailing factor for TIN ≤ 2.0	% RSD* of standard Area (TIN) ≤ 2.0
Precision	3512	1.0	0.3	4363	0.9	0.3
Intermediate precision	3912	1.0	0.2	4578	1.0	0.4
At 1.7 mL min^−1 flow rate	3163	1.0	0.3	3917	0.9	0.4
At 1.3 mL min^−1 flow rate	3802	1.0	0.2	4789	0.9	0.2
At 55°C column temp.	3128	1.0	0.3	3938	0.9	0.1
At 45°C column temp.	3757	1.0	0.3	4594	0.9	0.3
Mobile phase THF +5%	3117	1.0	0.4	4070	0.9	0.5
Mobile phase THF −5%	3701	1.0	0.1	4416	0.9	0.3

*Determined on five values. THF: tetrahydrofuran.