Separation and Pre-concentration of Cadmium, Copper, Lead, Nickel and Zinc by Solid-Liquid Extraction of their Cocrystallized Naphthalene Dithizone Chelate in Saline Matrices

Abstract

Um procedimento em batelada é proposto para separação e pré-concentração de cádmio, chumbo, níquel e zinco em amostras de salmoura. O método baseia-se na adsorção dos íons metálicos sobre a fase sólida composta de ditizona co-cristalizada com naftaleno microcristalino, na faixa de pH de 8,5 -9,1. Ácido nítrico é utilizado para re-extrair os cátions da fase sólida, os quais são determinados por ICP-OES. Vários parâmetros, tais como efeito do pH, do tempo de agitação e da quantidade da fase sólida foram estudados sistematicamente visando otimizar as condições para a determinação de quantidades traço de Cd, Cu, Pb, Ni e Zn em amostras sintéticas de salmoura. Os limites de detecção obtidos, expressos em µg L -1 , foram: 44 (Zn), 11 (Ni), 30 (Cd), 47 (Pb) e 11 (Cu). A precisão do procedimento foi estabelecida pela medida de 10 replicatas com 250 µg L -1 de cada íon e os desvios padrão relativos foram de 2,71 % (Cd), 2,15 % (Cu), 1,53 % (Pb), 2,47 % (Ni) e 2,78 % (Zn). A exatidão do procedimento foi confirmada pelo método de adição de analitos e os resultados obtidos indicaram recuperação quantitativa (≥ 95 %).A procedure for separation and pre-concentration of trace amounts of cadmium, copper, lead, nickel, and zinc in brine samples has been proposed. It is based on the adsorption of metal ions onto dithizone co-crystallized with microcrystalline naphthalene, in the pH range 8.5-9.1. Nitric acid is used to back-extract the cations from the solid phase, which are measured by ICP-OES. Various parameters, such as the effect of pH, stirring time, and amounts of solid phase, have been studied in detail, to optimize the conditions for the determination of trace amounts of Cd, Cu, Pb, Ni and Zn in synthetic brine samples. The limits of detection values expressed in µg L -1 are 44 (Zn), 11 (Ni), 30 (Cd), 47 (Pb) and 11 (Cu). The precision of the procedure was determined by running 10 replicate samples, each one containing 250 µg L -1 of each element and the relative standard deviations were 2.71 % (Cd), 2.15 % (Cu), 1.53 % (Pb), 2.47 % (Ni), and 2.78 % (Zn). The accuracy of the procedure was confirmed by applying the analyte additions method and the results indicated that quantitative recoveries (≥ 95 %) were obtained.

Determination of cadmium by flame-atomic absorption spectrometry after preconcentration on silica gel modified with cupferron

“…Spinola Costa et al 11 described a preconcentration factor of 13 and limit of detection of 30 µg L -1 for the determination of cadmium in brine samples by ICP OES, while de Melo Gomes et al 12 obtained a preconcentration factor of 20, for the analysis of fuel ethanol. Pereira and Arruda 13 described a preconcentration factor of 100 using vermicompost as adsorbed material for the determination of 5 µg L -1 level of cadmium.…”

Immobilization of the Thenoyltrifluoroacetone on Sodium Dodecyl Sulfate Modified Magnetite Nanoparticles for Magnetic Solid Phase Extraction of Pb (II) from Water Samples

“…Thus, in order to protect MNPs from possible damages during and after synthesis process and make them more selective to certain considered analyte, they must be coated with appropriate modifying agents to fulfill complexation with analyte and high yield extraction. Recently, various studies have represented the utilization of coating agents such as tetraethyl orthosilicate-(3-aminopropyl)trimethoxysilane (TEOS-APTMS) [41], dithizone-sodium dodecyl sulfate (DTZ/SDS) [42], 3-(trimethoxysilyl)-1-propanethiol-ethylene glycol bis-mercaptoacetate (TMSPT-EGBMA) [43], cetyltrimethylammonium bromide (CTAB) [44], polydopamine [45] and amino group (NH 2 ) [46] to imprint functional groups of thiol, carboxylic and amino on the surface of MNPs for the pre-concentration process of trace metal ions.…”

Flame atomic absorption spectrometric determination of Cd(II), Ni(II), Co(II) and Cu(II) in tea and water samples after simultaneous preconentration of dithizone loaded on naphthalene

“…These include Chromosorb 108 [10], Diaion SP-850 resin [11], cellulose functionalized with 8-hydroxyquinoline [12], chemically modified silica gel with aminothioamidoanthraquinone [13] and polyurethane foam functionalized with a-naphthol [14]. Naphthalene coprecipitated with methyl trioctyl ammonium chloride [15] or tetraoctyl ammonium bromide [16], naphthalene loaded with different ligands such as 2,6-bis(Nphenyl carbamoyl) pyridine [17], 1-(2-pyridylazo)-2-naphthol (PAN) [18], N,N-(4-methyl-1,2-phenylene)diquinoline-2-carboxamide [19] and dithizone [20,21] have also been used as solid phase extractors for determination of trace metal ions.…”