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UVA/UVB sunscreen determination by second-order derivative ultraviolet spectrophotometry
J S Azevedo1, N S Viana Junior, C D Vianna Soares
1Departamento de Produtos Farmacêuticos, Faculdade de Farmácia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
Farmaco (Societa Chimica Italiana : 1989)
|November 11, 1999
Summary
This study introduces a cost-effective spectrophotometry method for analyzing UVA/UVB sunscreens. The developed technique accurately quantifies key protective agents, 2-hydroxy-4-methoxy-benzophenone-5-sulphonic acid (BZP) and 2-phenylbenzymidazole-5-sulphonic acid (PBS).
Area of Science:
- Analytical Chemistry
- Cosmetic Science
- Spectroscopy
Background:
- UVA/UVB protective agents are crucial in sunscreens and cosmetics.
- Accurate analytical methods are needed for quality control of these agents.
- Spectrophotometry offers a cost-effective approach for analyzing compounds with varying characteristics.
Purpose of the Study:
- To develop and validate a second-order derivative ultraviolet spectrophotometry method.
- To determine combined UVA and UVB protective substances in a sunscreen gel.
- To evaluate the accuracy and precision of the analytical method.
Main Methods:
- Analysis of 2-hydroxy-4-methoxy-benzophenone-5-sulphonic acid (BZP) using zero-peak (ZP) at 356.0 nm in 95% ethanol.
- Determination of 2-phenylbenzymidazole-5-sulphonic acid (PBS) using ZP at 317.5 nm and peak-peak (PP) at 317.5-323.0 nm in 0.1 mol L-1 triethanolamine.
- Second-order derivative ultraviolet spectrophotometry was employed for both substances.
Main Results:
- High linearity (0.9999) was achieved for both BZP and PBS.
- Excellent precision was demonstrated: 1.12% (ZP) for BZP, and 0.55% (ZP) and 0.63% (PP) for PBS.
- Average recovery rates were high, indicating method accuracy: 97.28% (ZP) for BZP, and 103.13% (ZP) and 103.71% (PP) for PBS.
Conclusions:
- Second-order derivative ultraviolet spectrophotometry is a reliable and effective method.
- The validated method allows for accurate quantification of BZP and PBS in sunscreen formulations.
- This analytical approach supports quality control and development in the cosmetic industry.