A recent study1 compared the results of data collected with both Monochromatic Diffuse Reflectance Spectroscopy (MDRS) and Polychromatic Diffuse Reflectance Spectroscopy (PDRS) to the conventional in vivo erythemal SPF test method (ISO 24444:2019) results for sun protection products to evaluate the repeatability, accuracy and method equivalency of the HDRS techniques.
The results of this study demonstrate that HDRS (ISO/CD 23698) is a rapid, accurate and precise alternative instrumental method of analysis to ISO 24444:2019.
Monochromatic DRS (MDRS), from Solar Light Company, LLC, utilizes two synchronized monochromators – a monochromatic source to illuminate the skin, and the diffusely reflected monochromatic light is measured with a photomultiplier. In Polychromatic DRS (PDRS), from Solar Light Company, LLC, a polychromatic source illuminates the skin, and the diffusely reflected polychromatic light is measured with a photomultiplier. In both techniques, a custom light guide array interface ensures repeatable and sensitive illumination and collection of the measured diffuse reflectance intensity to yield diffuse reflectance UVA-PF and SPF values.
1. Ruvolo E, Rohr M, Oliveira S, Nogueira L, Carvalho J, Cole C. Multi-laboratory study of hybrid diffuse reflectance spectroscopy to assess sunscreen SPF and UVA-PFs. Photodermatol Photoimmunol Photomed. 2021;37:511 520.