@article{korn_ferreira_teixeira_costa_1999,  title={Spectrophotometric Determination of Zinc Using 7-(4-Nitrophenylazo)-8-Hydroxyquinoline-5-Sulfonic Acid},  volume={10},  ISSN={0103-5053},  url={https://doi.org/10.1590/S0103-50531999000100008},  DOI={10.1590/S0103-50531999000100008},  number={1},  journal={Journal of the Brazilian Chemical Society},  publisher={Sociedade Brasileira de Química},  author={Korn, Maria das Graças Andrade and Ferreira, Adriana Costa and Teixeira, Leonardo Sena Gomes and Costa, Antonio Celso Spínola},  year={1999},  month={Jan},  pages={46–50} }