Determination of the sun protection factor of sunscreens

Abstract Proper sun protection plays a key role in protecting against the harmful effects of UV radiation from the sun. Using sunscreen products protects the skin from sunburn, prevents it from ageing and reduces the risk of skin cancer. The aim of this research is to measure the sun protection factor (SPF) of commercially available products and compare it with the SPF value on the packaging. We also looked at whether the ratio and combination of sunscreen ingredients affect the effectiveness of the product. The SPF values of eight sun-screen products were tested. The value was determined using an in vitro method based on absorbance measurements with a UV spectrophotometer. Based on the results obtained, the actual SPF values of the products were calculated using Mansur’s formula. The SPF values we determined differed by 46.82% on average from the values indicated on the packaging of the sunscreen products. For those products where the SPF value on the packaging was higher (SPF 50), a larger deviation from the measured values was observed, but some deviation was observed for all products tested. However, the combination and proportion of substances in the products did not influence the differences obtained.