Flame atomic absorption spectrometric determination of trace amounts of cobalt after cloud point extraction as 2-[(2-Mercaptophenylimino)methyl]phenol complex

Abstract

Um procedimento de extração no ponto nuvem (CPE) foi desenvolvido para a separação e pré-concentração de baixas concentrações de cobalto previamente à determinação por espectrometria de absorção atômica em chama (FAAS). O procedimento é baseado na formação do complexo de Co(II) com 2-[(2-mercaptofenilimino)metil]fenol (MPMP), seguido pela extração em fase rica em surfactante Triton X-114. Alguns parâmetros importantes que afetam a complexação e extração, tais como pH, concentrações do agente quelante e do surfactante, temperatura e tempo de equilíbrio, foram otimizados. Sob condições ótimas, a pré-concentração de um volume de 25 mL da amostra resultou em um limite de detecção de 0,21 µg L -1 , um fator de enriquecimento de 97 e um desvio padrão relativo de 1,2% (n = 8, 60 µg L -1 ) para a determinação de Co(II) por FI-FAAS. O método foi aplicado com sucesso para amostras de água, vitamina B 12 e ampolas de complexo B. A exatidão do método foi comprovada por experimentos de adição-recuperação, análise independente por espectrometria de absorção atômica com forno de grafite e determinação de Co em material de referência certificado.A cloud point extraction (CPE) procedure was developed for the separation and preconcentration of trace amounts of cobalt prior to its determination by flame atomic absorption spectrometry (FAAS). The procedure is based on the formation of Co(II) complex with 2-[(2-mercaptophenylimino) methyl]phenol (MPMP) followed by its extraction into a Triton X-114 surfactant-rich phase. Some important parameters affecting both complexation and extraction, such as pH, concentrations of chelating agent and surfactant, temperature, and time of equilibration, were optimized. Under optimum conditions, the preconcentration of a volume of 25 mL of sample resulted in a limit of detection of 0.21 µg L -1, an enhancement factor of 97, and a relative standard deviation of 1.2 % (n = 8, 60 µg L -1 ) for the determination of Co(II) by FI-FAAS. This procedure was successfully applied to water, vitamin B 12 and B-complex samples. The accuracy was assessed employing addition-recovery experiments, independent analysis by graphite furnace atomic absorption spectrometry and by using a certified reference material.

Determination of Cobalt in Food, Environmental and Water Samples with Preconcentration by Dispersive Liquid-Liquid Microextraction

“…In recent decades the developments of preconcentration steps prior to analytical determinations of trace level compounds have been explored in considerable depth. In this way, a number of accurate and reliable methods have been developed for Co(II) determination [7][8][9][10][11][12][13][14][15][16][17][18][19].…”

Indirect Determination of Sulfadiazine by Cloud Point Extraction/Flow Injection‐Flame Atomic Absorption (CPE/FI‐FAAS) Spectrometry

“…5,7,8,14,15,18 Therefore, the need for a sensitive, simple and reliable method for the determination of sulfadiazine is well recognized. Flame atomic absorption spectroscopy is a versatile, simple and high speed instrument for direct determination of metal ions, [20][21][22][23][24][25] but its use in indirect determination of nonmetallic anions and drugs is limited. [26][27][28][29][30][31][32][33] To the best of our knowledge there is no report on the use of FAAS for indirect determination of sulphonamides drugs.…”

Selective cloud point extraction and preconcentration of trace amounts of cadmium prior to flame atomic absorption spectrometric determination

“…But, its limitation is low detectability, which may be improved by a preconcentration step. [5][6][7][8][9] Several methods for the separation and preconcentration of metals have been developed, enhancing the sensitivity and the versatility of the instrumental analytical techniques.…”