An analytical method for the quantitative determination of iron ion chelating capacity: development and validation

Iron is a fundamental microelement for human life; however, deficiencies or excesses of these metal ions can cause severe complications and mortality. Chelators are compounds that bind and inhibit iron. Ultraviolet-visible (UV-vis) spectrophotometric methods are key analytical tools in the identification of chemical entities, with the benefits of having good precision and accuracy, and the equipment being easily available as well as quick and simple to implement. In this study, we aimed to provide an alternative, cheaper method for the quantification of iron ion chelation by substituting ferrozine for gallic acid and validating its use with UV-vis according to official ANVISA and ICH guidelines. The parameters assessed were specificity, linearity, precision, accuracy, robustness, and finally, the percentage of iron ions chelating was calculated. The results demonstrated that this method was accurate, simple, specific, selective, precise, and reproducible, and was successfully validated for the determination of iron ions chelating. The percentage of iron ions chelating, promoted by the standard chelator EDTA, was 45% and 47% for Fe2+ and Fe3+, respectively. It is concluded that this new method is beneficial in terms of its simplicity, rapidness, low cost, and the fact that it produces very low levels of dangerous residues.(AU)

Comparative study on nitrate determination methods in potable water / Estudo comparativo de métodos para determinação de nitrato em águas para consumo humano

Four techniques were studied and compared for determining nitrate in water for human consumption: phenoldissulphonic acid, UV spectrophotometric at 205nm, modified UV spectrophotometric at 205nm , and UV spectrophotometric at 220/275nm. The were assessed in order to select the most reliable with respect to precision and accuracy for being used in the Brazilian official public health laboratories network. Based on the obtained results, both techniques UV spectrophotometric at 220/275nm , and at 205nm presented statistically adequate performance characteristics for being employed in routine laboratory analyses .In addition, both technique are easy to perform, make use of one reagent only , and they present rapid testing results in determining nitrates in water with low content of organic materials.

Foi realizado um estudo comparativo entre quatro métodos para determinação de nitrato em águas destinadas ao consumo humano: ácido fenoldissulfônico, espectrofotométrico UV a 205nm, espectrofotométrico UV a 205nm modificado e espectrofotométrico UV a 220/275nm. Os métodos foram avaliados a fim de selecionar os mais adequados quanto à precisão e exatidão para serem aplicados na rede oficial de laboratórios de saúde pública. Com base nos resultados obtidos, os métodos espectrofotométricos UV a 220/275nm e espectrofotométrico UV a 205nm apresentaram características de desempenho adequadas estatisticamente para análise de rotina laboratorial, além de serem métodos de fácil execução, utilizarem reagente único e apresentarem resultados imediatos na determinação de nitratos em águas com baixo teor de matéria orgânica.