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In vitro evaluation of sun protection factors of sunscreen agents using a novel UV spectrophotometric technique


Bleasel, MD and Aldous, S, In vitro evaluation of sun protection factors of sunscreen agents using a novel UV spectrophotometric technique, International Journal of Cosmetic Science, 30, (4) pp. 259-270. ISSN 1468-2494 (2008) [Refereed Article]

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DOI: doi:10.1111/j.1468-2494.2008.00453.x


A method for the in vitro determination of low- and high-value sun protection factors (SPF) of sunscreens using artificial substrates and a novel pseudo double beam (PDB) mode of operation of a standard double beam UV spectrophotometer is described. The method allows transmittance to be calculated from detector responses of reference and sample beams measured at different gain levels and facilitates the accurate quantification of low levels of electromagnetic radiation transmitted through highly absorbing samples. The spectrophotometer was modified to hold quartz diffusing plates on which a substrate [Transpore™ adhesive tape or human stratum corneum obtained from a skin surface biopsy (SSB)] and the sunscreens to be tested were applied. The PDB mode of operation increased the effective linear range of the detector response of the spectrophotometer by a factor of approximately 20000-fold, enabling the in vitro SPF determination technique to be applied to both high and low SPF value sunscreens. Eight commercial sunscreens with known SPF values ranging from 4 to 77, previously determined by in vivo methods, were tested in vitro using both test substrates and correlations between the in vivo and in vitro values were determined. SPF values determined using the in vitro method correlated well with the known in vivo results (Transpore™ tape, R2 = 0.611; SSB, R2 = 0.7928). The in vitro SPF obtained for one of the tested products differed substantially from the cited in vivo SPF value. Independent in vitro and in vivo re-evaluation of the SPF of this product matched the value predicted by the present method much more closely than the originally cited in vivo value. All determined SPFs were ordered correctly in comparison to in vivo ranking and the technique appeared to correctly identify a sunscreen that had a labelled SPF value that was significantly higher than its true SPF.

Item Details

Item Type:Refereed Article
Keywords:in vitro • pseudo-double beam mode • skin surface biopsy • spectrophotometer • sun protection factor
Research Division:Biomedical and Clinical Sciences
Research Group:Pharmacology and pharmaceutical sciences
Research Field:Pharmaceutical sciences
Objective Division:Health
Objective Group:Clinical health
Objective Field:Clinical health not elsewhere classified
UTAS Author:Bleasel, MD (Dr Martin Bleasel)
UTAS Author:Aldous, S (Dr Stephen Aldous)
ID Code:53187
Year Published:2008
Deposited By:Pharmacy
Deposited On:2008-11-10
Last Modified:2011-10-10
Downloads:19 View Download Statistics

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