Chemical Analysis of Sunscreen: Determining SPF with Ultraviolet Light Measurement

Summer is just around the corner, and the longer days and warmer weather are drawing people outside for some much-anticipated sunshine. Evidence of sunny weather is popping up at local drug stores and supermarkets, where sunscreen has once again permeated the shelves, reminding people of the importance of skin protection.

baby sunscreen chemical analysis
As the weather turns warmer and more time is spent outside, the need to protect your skin from the sun increases. Sunscreen sales skyrocket in the summer, as consumers look for effective products.
Image Source: Flickr user Boudewijn Berends


Sunscreen undergoes various stages of processing before it reaches the consumer. The most important feature is the sun protection factor (SPF) measurement, which depends on chemical analysis for its determination. The SPF number you find on that bottle of lotion indicates the level of protection the product offers from harmful UV rays. However, accurately measuring the level of protection for a given product is a highly technical process. UV spectrophotometry offers an effective method of chemical analysis that can help to determine SPF. This data can be obtained quickly and accurately, giving a quantifiable number to show the exact level of protection provided.

Evaluating SPF with UV Spectrophotometry

How does SPF determination work? According to the American Melanoma Foundation (AMF),

the Sun Protection Factor (SPF) displayed on the sunscreen label ranges from 2 to as high as 50 and refers to the product’s ability to screen or block out the sun’s harmful rays. For example, if you use a sunscreen with an SPF 15, you can be in the sun 15 times longer that you can without sunscreen before burning. Consumers need to be aware that SPF protection does not increase proportionally with an increased SPF number. While an SPF of 2 will absorb 50% of ultraviolet radiation, an SPF of 15 absorbs 93%, and an SPF of 34 absorbs 97%.

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The determination of these numbers and their correlation with ultraviolet radiation protection is essentially what makes sunscreen a useful product for consumers. Using UV spectrophotometry to perform chemical analysis on these products can provide a rapid determination of the effectiveness of the product and also help accurately determine the correct value to correlate with the SPF standard numbering system.

In recent years, evidence has linked sun exposure to premature aging and wrinkles as well as many dangerous forms of skin cancer. According to an EWG Sun Safety online article:

The chemicals that form a product’s sun protection factor are aimed at blocking ultraviolet B rays, which are the primary cause of sunburn and non-melanoma skin cancers such as squamous cell carcinoma (von Thaler 2010). Ultraviolet A rays penetrate deeper into the skin and are harder to block with sunscreen ingredients approved by the federal Food and Drug Administration for use in U.S. sunscreens.

With the risk of skin cancer on the rise in the U.S., sunscreen manufacturers are continuously on the lookout for new formulas to increase protection against harmful UVA rays while still maintaining compliance with FDA regulations. Using UV spectrophotometry to develop a chemical analysis of these products can help to determine the protection factor of ultraviolet A rays in all new formulas that comply with regulations.

white lotion chemical analysis
New sunscreen formulations are looking for ways to develop better protection from UVA radiation, the main skin cancer-causing element accompanying sun exposure.
Image Source: Flickr user Carnivore Locavore


Creating a Better Formula with UV-Visible Spectroscopy

Recent research has used UV/VIS spectroscopy for the chemical analysis and evaluation of common sunscreen formulas, in hopes of creating a more effective and beneficial product. Using UV-visible spectrophotometry, absorption of UVA and UVB rays could be used to determine the effectiveness of these formulations. Studies found that the product’s range of absorption was more important than the SPF for effectiveness. Thus, sunscreen manufacturers are highly motivated to use spectrophotometric chemical analysis to measure efficacy more accurately.

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Furthermore, using a specific spectrophotometric formula for SPF determination allows for the creation of specific chemical formulations that offer the highest levels of effectiveness. Using spectrophotometric instrumentation to determine these factors provides an affordable method of chemical analysis. Sunscreen manufactures rely on these methods to develop quality products and maintain high levels of protection as intended for use.

sunscreen chemical analysis
Sunscreen is an ever-growing market, and consumers continue to look for quality products that meet the highest level of protection.
Image Source: Flickr user haiderzs


UV Spectroscopy and Instrumentation

At HunterLab, we are committed to developing instruments that help manufacturers achieve the highest level of quality in their products. As new sunscreen formulations emerge, new methods of chemical analysis are being improved upon by using spectrophotometric technology. HunterLab continues to be a leader in innovative, UV-VIS spectrophotometric technology and is a trusted resource for discovering the many applications of these tools. We work together with industry leaders to develop the highest level of instrumentation that is specifically formulated to meet your needs. For more information on the HunterLab commitment to quality and consumer service, contact us today.

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