Micelle-mediated extraction and spectrophotometric determination of ammonia in water samples utilizing indophenol dye formation

Abstract

Foi investigado um processo de extração rápido, seletivo e sensível por ponto nuvem para extrair o indofenol, formado na reação de Berthelot com amônia, a partir de soluções aquosas. Utilizou-se a mistura do surfactante não iônico, Triton X-114, e do catiônico, brometo de cetiltrimetilamônio (CTAB). O método foi baseado na cor do corante indofenol produzido pela reação da amônia com fenol em meio alcalino e condições oxidantes, e na extração por ponto nuvem. Os efeitos da reação e dos parâmetros da extração foram estudados e otimizados. A linearidade obedeceu ao intervalo de 2,00-125,00 ng mL-1 de amônia. O limite de detecção do método foi de 1,00 ng mL-1. Testou-se também o efeito de interferência de alguns íons comum. Aplicou-se o método para a determinação do íon amônio em amostras de água naturais. A rapid, selective and sensitive cloud point extraction process using the mixture of nonionic surfactant, Triton X-114, and cationic surfactant, cetyltrimethylammonium bromide (CTAB), to extract indophenol formed in the Berthelot reaction with ammonia from aqueous solutions was investigated. The method was based on the color reaction of ammonia with phenol under suitable oxidizing conditions in alkaline medium and cloud point extraction of produced indophenol dye. Effects of reaction and extraction parameters were studied and optimum parameters were established. Linearity was obeyed in the range of 2.00-125.00 ng mL-1 of ammonia. The detection limit of the method was 1.00 ng mL-1 of ammonia. The interference effect of some common ions was also tested. The method was applied to the determination of ammonium in natural water samples.

Simple colorimetric assay for dehalogenation reactivity of nanoscale zero-valent iron using 4-chlorophenol

“…7-9. It was previously reported that Ni is a suitable second metal for 4-chlorophenol degradation, which can provide reducing reactivity for atomic hydrogen production [8,17]. The higher catalytic reactivity of Ni was also reported in several studies on 1,1,1-trichloroethane reduction [25] and hydrogen generation in the reaction with water [28].…”

“…In the last decade, application of ZVI for reduction of chlorophenols has been extensively studied [8,[15][16][17][18]. Chlorophenol can be reduced to phenol via dehalogenation, driven from electron transfer, and it is generally accepted that phenol is the only product during this process [16,17].…”

Graduated characterization method using a multi-well microplate for reducing reactivity of nanoscale zero valent iron materials

“…The indophenol reaction is the name given to the reaction of monochloramine and a phenol, which results in the formation of a blue indophenol dye, which can then be determined spectrophotometrically [18,19]. This reaction is highly specific for ammonium, and in the presence of a suitable catalyst, extremely high sensitivity is attainable.…”

Extraction of ammonia and nitrite using modified magnetite iron oxide nanoparticles before spectrophotometric determination in different water samples

“…The determination of ammonia at lower concentrations typically entails a chemical reaction to transform the analyte into a derivative amenable for colorimetric [1,[3][4][5], fluorimetric [6] or chemiluminescence detection [7]. In this sense, the reaction with indophenoltype reagents is still the most widely used approach [1,[3][4][5]8,9].…”

“…Nevertheless, these colorimetric standard assays are not sensitive enough to be directly applied to water samples. Therefore, in order to circumvent the low sensitivity of spectrophotometric methods several sample preparation techniques such as solid-phase extraction (SPE) [2,8,14,15], cloud point extraction (CPE) [5,16,17] or liquid-phase microextraction (LPME) [18][19][20] have been developed. These techniques help in separation and preconcentration of nitrite and ammonium in aqueous matrices prior to spectrophotometric determination.…”