Therefore,with low performance intrumentation, self-standing Transpore should be chosen, but if the dynamic range of the intrument is good enough Transpore on quartz should be preferred.
3.4. In vitro determination of SFP value as indicated on the product label, whereas the y-axis registers the value obtained from our measurements. It can be easily observed that the linear correspondences among in tro and label values have not always been satisfied. In the case of roughened quartz, vitro-skin and Transpore correlation between the in vitro SPF and label values can be established, but they are not 1:1 the slope of the linear regression curves resluts higher than than 1 (1.5; 1.55 and 5.9 respectively); probably the slope could be modified by applying different quantities instead of 1 mg/cm 2 as demonstrated by other authors. The results obtained with PTEE and PMMA plates are more critical . For PTEE . In vitro SPF/Label correlation seem to be different for low and high SPF values; it has been already demonstrated that better results are obtained when a smaller amount of sunscreen is applied. In case of PMMA, SPF values have been calculated assuming that the substrate used for A recovering was with or without glycerine; results were almost equivalent. While PMMA appear to be a first choice for UVA in vitro testing. Our expermental results suggest that for in vitro SPF other substrates could provide better performances. In our study .