J. Cosmet. Sci., 65, 147–159 (May/June 2014) 147 Method for screening sunscreen cream formulations by determination of in vitro SPF and PA values using UV transmission spectroscopy and texture profi le analysis WATCHAREE KHUNKITTI, PANITTA SATTHANAKUL, NETI WARANUCH, TASANA PITAKSUTEEPONG, and PICHET KITIKHUN, Faculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand (W.E., P.S.), and Cosmetics and Natural Products Research Center, Faculty of Pharmaceutical Science, Naresuan University, Phitsanulok 65000 (N.W., T.P., P.K.), Thailand. Accepted for publication April 21, 2014. Synopsis Formulation of sunscreen products to obtain high values of sun protection factor (SPF) and protection from ultraviolet A (PA) is challenging work for cosmetic chemists. This study aimed to study factors affecting SPF and PA values using ultraviolet transmission spectroscopy as well as texture profi les of sunscreen formulations using 23 factorial designs. Results demonstrate that the correlation coeffi cient between the labeled SPF values of counter-brand sunscreen products and the in vitro SPF values was 0.901. In vitro SPF determination showed that the combination effect of phase volume ratio (PVR) and xanthan gum caused a signifi cant increase to the SPF values of the formulations, whereas the interaction effect between PVR and stearic acid signifi cantly decreased the SPF value. In addition, there was the interaction effect between xanthan gum and stearic acid leading to signifi cant reduction of hardness, compressibility, and pH, but signifi cantly increasing the adhe- siveness. All tested factors did not signifi cantly affect the cohesiveness of tested formulations. In conclusion, apart from sunscreen agents, the other ingredients also affected the SPF and PA values. The calculated SPF values range from 21 to 60. However, a selected formulation needs to be confi rmed by the standard method of testing. In addition, the physical, chemical, and biological stability shelf life and sensory evaluation of all formulations need to be evaluated. INTRODUCTION It is generally known that ideal sunscreen products should be able to protect skin from damage from ultraviolet (UV) radiation (290–400 nm). Long-term exposure to UVB (290–320 nm) and UVA (320–400 nm) may cause sunburn, immunosuppression, and skin cancer (1–3). The effi cacy of sunscreen products may be indicated by numerical rat- ing of sun protection factor (SPF) and UV-A protection (PA). Several attempts have been made to develop in vitro SPF testing methods (1,4–11), but there is no offi cially recognized Address all correspondence to Watcharee Khunkitti at watkhu@kku.ac.th.