UV absorbing substances

A hst of uv absorbing substances found useful in protective sunscreen products is provided in Table 13. Some information on the levels permitted in products in both the United States and the EEC is included. Descriptions and specifications of sunscreens have been pubflshed (55). 

For the detection of UV-absorbing substances that show no fluorescence, TLC plates are very often prepared with a fluorescence indicator. Commonly, an inorganic dye... 

Karsten U, Bischof K, Flanelt D, Tug H, Wiencke C (1999) The effect of UV-radiation on photosynthesis and UV-absorbing substances in the endemic Arctic macroalga Devaleraea ramen-tacea (Rhodophyta). Physiol Plant 105 58-66... 

HPLC has transformed quality control in the pharmaceutical and chemical industries, as it provides a rapid means of checking the purity of samples and even allows for the purification of small amounts of samples by preparative HPLC. The majority of such systems use L V to detect and quantify substances as they elute from the separative column. UV detectors are usually variable wavelength and can be used to detect molecules with absorption maxima above 210 nm by measuring the absorbance of the eluent. When a UV-absorbing substance is eluted from the HPLC column, it absorbs UV radiation at the appropriate wavelength for its chromophore. The amount of UV absorbed is proportional to the quantity of substance being eluted, and is converted into a peak on a chart recorder. Integration of each peak allows the relative quantities of the components of the solute to be determined. 

Dionisio-Sese, M. L., Ishikura, M., Maruyama, T., and Miyachi, S., UV-absorbing substances in the tunic of a colonial ascidian protect its symbiont, Prochloron sp., from damage by UV-B radiation, Mar. Biol., 128, 455, 1997. 

Shibata, K., Pigments and a UV-absorbing substance in corals and a blue-green alga living in the Great Barrier Reef, Plant Cell Physiol., 10, 325, 1969. 

Iwamoto, K. and Aruga, Y., Distribution of the UV-absorbing substance in algae with reference to the peculiarity of Prasiola japonica Yatabc, J. Tokyo Univ. Fish, 60, 43, 1973. 

Yoshida, T. and Sivalingham, P. M., Isolation and characterization of the 337 mp UV-absorbing substance in red alga, Porphyra yezoensis Ueda, Plant Cell Physiol., 11, 427, 1970. 

Takano, S., Nakanishi, A., Uemura, D., and Hirata, Y., Isolation and structure of a 334 nm UV-absorbing substance, porphyra-334 from the red alga Porphyra tenera Kjellman, Chem. Lett., 419, 1979. 

Ultraviolet analyzers have been discussed in previous subsections in connection with the measurement of the concentrations of specific materials. Therefore, only a summary of their features is provided here. Table 3.43 provides a list of UV-absorbing substances. 

J. Kobayashi, H. Nakamura, Y. Hirata (1981). Isolation and structure of a UV-absorbing substance 337 from the ascidian Halocynthia roretzi. Tetrahedron Lett., 22, 3001-3002. 

I. Sekikawa, C. Kubota, T. Hiraoki, I. Tsujino (1986). Isolation and structure of a 357 nm UV-absorbing substance, usujirene, from the red alga Palmaria palmata (L.) O. Kuntze. Jpn. J. PhycoL, 34,185-188. 

M. Ishikura, C. Kato, T. Maruyama (1997). UV-absorbing substances in zooxanthel-late and azooxanthellate clams. Mar. Biol, 128, 649-655. 

The most active natural UV-absorbing substances are the MAAs that are produced by algae and possess tremendous implications for being used as medicinal foods. A human study showed that a cream containing MAAs from the red alga P. umbilicalis efficiently protects the skin against UVA exposure on a typical working day (Schmid et ah, 2003). 

UV absorber. Substance which absorbs radiant energy in the ultraviolet wavelength added to adhesives, plastics, rubbers, coatings, etc., to decrease light sensitivity and consequent discoloring and degradation. 

This method is successfully used if direct spectrophotometric determining of ozone is disturbed by UV-absorbing substances on account of UV adsorption at 238 nm, or if this method does not offer sufficient sensitivity. 

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