ABSTRACT
Nitrogen-doped carbon nanoparticles (N-CNPs) with a fluorescence quantum yield of 15.1％ were prepared from sucrose and urea in oleic acid medium by a one-pot solvothermal method.A new approach for quick,sensitive,and selective determination of free chlorine in water was developed based on fluorescence quenching of N-CNPs.There existed a good linear correlation between the fluorescence quenching and the concentration of ClO-in the range of 0.05-25.00 μmol/L.The limit of detection (LOD,S/N =3) was estimated to be 23 nmol/L.This method can be applied to the determination of free chlorine in real water samples.
ABSTRACT
INTRODUCCIÓN: en Cuba se han desarrollado las primeras tabletas efervescentes de 3,5 mg dicloroisocianurato de sodio, como ingrediente activo no terapéutico, el cual libera una determinada cantidad de cloro al disolverse en un litro de agua, capaz de inducir a una adecuada desinfección del agua potable y lista para ingerir después de transcurrido 30 min. OBJETIVO: desarrollar y validar un método analítico yodométrico, aplicable al control de la calidad de las tabletas efervescentes de 3,5 mg de dicloroisocianurato de sodio. MÉTODOS: para la cuantificación del contenido de cloro activo libre en las tabletas efervescentes, se empleó como técnica un método potenciométrico, utilizando electrodos de platino y solución valorada de tiosulfato de sodio 0,1 N. El método desarrollado fue validado según los parámetros exigidos para la categoría I, que incluye las técnicas destinadas a cuantificar principios activos en las formas terminadas. Adicionalmente se realizaron otras pruebas para evaluar la influencia del analista y el día en los resultados analíticos. RESULTADOS: los parámetros evaluados en la validación del método se encontraron dentro de los límites establecidos. El método resultó ser específico, lineal, exacto y preciso en el rango de concentraciones estudiadas. CONCLUSIONES: los resultados permiten que el método pueda emplearse de manera confiable y segura(AU)
INTRODUCTION: Cuba has developed the first effervescent 3.5 mg sodium dichloroisocyanurate tablets as a non-therapeutic active principle. This ingredient releases certain amount of chlorine when dissolved into a litre of water and it can cause adequate disinfection of drinking water ready to be taken after 30 min. OBJECTIVE: developing and validating an analytical iodometric method applicable to the quality control of effervescent 3.5 mg sodium dichloroisocyanurate tablets. METHODS: quantitation of the free active chlorine content in effervescent tablets by using a potentiometric method based on the platinum electrodes and the tittered 0.1 N sodium thiosulphate solution. The developed method was validated as per the category I parameters including the techniques for quantitation of the active principles in the finished forms. Additionally, other tests were conducted to evaluate the influence of the analyst and of the day on the analytical results. RESULTS: the evaluated parameters in the validation of the method were within the set limits. The method was specific, linear, exact and precise in the range of studied concentrations. CONCLUSIONS: the results proved that this method can be used in a safe reliable way(AU)
Subject(s)
Humans , Free Available Chlorine/methods , Water Disinfection/methods , Tablets , Cuba , Validation Studies as TopicABSTRACT
Ensaios de tratabilidade em bancada tendo cloreto férrico como coagulante foram conduzidos para avaliar efeitos da pré-ozonização e da inter-ozonização sobre variáveis de qualidade de águas em diversas etapas de tratamento: demanda de cloro livre (DCL), absorbância de luz ultravioleta em 254 nm (abs UV254) e concentração de matéria orgânica (MO). Para águas decantadas, a ozonização favoreceu a remoção de MO, mas não pareceu influenciar a redução da DCL, em relação aos ensaios sem ozonização. Para as águas filtradas, os ensaios com ozônio proporcionaram maiores remoções de MO e valores da relação DCL/MO do que os ensaios sem ozônio, porém estes últimos foram mais eficientes na redução da DCL. A ozonização da água bruta reduziu a concentração de MO e a abs UV254 mas não a DCL. A DCL imediata da água bruta foi estimada e pareceu não depender do tempo de contato.
Bench scale treatability tests with ferric chloride coagulation were conducted to assess effects of pre-ozonation, inter-ozonation on water quality variables of water samples in several stages of treatment: free chlorine demand (FCD), absorbance of Ultra Violet light in the 254 nm wavelength (UV254 abs) and organic matter (OM) concentration. Regarding settling, ozonation favored OM removal but did not seem to influence FCD reduction, as compared with tests without ozonation. Regarding filtration, tests with ozonation led to higher OM removals and FCD/OM ratios than tests without ozonation. However, tests without ozonation were more efficient in reducing the FCD. Raw water ozonation decreased OM and UV254 abs values but not FCD values. The immediate FCD was obtained for raw water and it did not seem to depend on contact time.
Subject(s)
Chlorine Demand , Organic Matter , Ozonation , Water Reservoirs , Water Quality , Water PurificationABSTRACT
Objective To identify the tones of yellow color of chlorinated water sample reacting with color reagent containing 3,3' ,5,5' -tetramethylbenzidine with the color of standard colorimetric series in process of determination of free chlorine in drinking water by colorimetry method. Methods The dispensation and the adding amount of color reagent into water sample were adjusted to select the optimum experimental conditions. Results The water sample reacting with color reagent showed expected yellow color at the concentration of HC1 in color reagent e" 0.5 mol/L. Conclusion The reaction of 50 ml water sample (0.1-0.5 mg/L free chlorine) with 1.00 ml color reagent at concentration of 0.3 g/L prepared by 0.50 mol/L HC1 revealed the same tone of yellow color as that on the standard colorimetric series in optical colorimetry method.