Commercial sunscreens contain various compounds that absorb or physically block UV radiation-properties that can be exploited when determining the concentrations of these compounds. Although UV absorbance spectroscopy has been used to evaluate sunscreens (1, 2), separation of components is preferred. Thin-layer chromatography (3) and gas-liquid chromatography (3, 4) have been investigated, but liquid chromatography with UV absorbance detection is better (3, 5-9).Early sunscreens contained p-aminobenzoic acid (PABA), and the UV absorbing qualities of this compound are well-documented (10,11). The popularity of PABA in the manufacture of cosmetics during the 1960's and 70's led to widespread use by people intent on acquiring a suntan without risking serious sunburn or worse. The American Cancer Society estimates that more than half a million new cases of skin cancer are diagnosed every year and that about 90% are caused by exposure to the sun. In a recently published article in this Journal, Taylor noted that 1 in 10 Americans will contract skin cancer during their lifetime (12).

Procedure to determine the amount of calcium in calcium carbonate coated analgesic tablets using an atomic absorption spectrophotometer.

No abstract

A collection of organic chemistry experiments based on olive oil are described here.