Indirect fluorimetric detection of alkali and alkaline earth metal ions in capillary zone electrophoresis with cerium(III) as carrier electrolyte

Bächmann, K.; Boden, J. C.; Haumann, I.

doi:10.1016/0021-9673(92)85418-s

Cited by 80 publications

(28 citation statements)

References 15 publications

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“…Therefore, pH 6.0 is desirable for BGE pH, as it offers the best separation and matching of the natural pH of the milk samples. Methanol is added as an organic additive and interacts through the weak ion-dipole interaction [24] with the cations present in the buffer. This gives rise to a noticeable reduction in the mobility of various divalent cations upon addition of methanol, leading to a significant improvement in the resolution of Na Fig.…”

Section: Selection and Optimization Of Bgementioning

confidence: 99%

Separation and determination of metal cations in milk and dairy products by CE

2007

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To prevent casein adsorption and improve between-run repeatability, a CE procedure is developed for cation analysis in milk using a modified imidazole/alpha-hydroxyisobutyric acid (HIBA) BGE system to operate at pH 6 to match the pH of milk and elevate imidazole concentration to enhance its buffer action. The procedure is shown to produce a fast, economic and efficient method for cation separation in milk with only simple dilution. Upon direct hydrodynamic injection of diluted milk sample at 8 cm for 30 s in an uncoated column with a BGE consisting of 10 mM imidazole, 10 mM HIBA and 10% methanol at pH 6.0 under +18 kV, baseline separation was achieved for K(+), Na(+), Ca(2+), Mg(2+), Mn(2+), Cd(2+), Co(2+), Ni(2+)and Zn(2+). Agreeable results at 95% confidence level were obtained using CE and inductively coupled plasma-atomic emission spectrometry (ICP-AES) for milk samples after protein removal. Baseline-resolved peaks for essential minerals were obtained for fresh and non-refrigerated reconstituted milks. Long-term stability was demonstrated by repeated determinations without rinsing and improvement in repeatability was shown by rinsing with 60 mM SDS in BGE. Information on metal speciation useful for nutritional assessment was obtained from CE to complement the ICP methods.

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Section: Selection and Optimization Of Bgementioning

confidence: 99%

Separation and determination of metal cations in milk and dairy products by CE

2007

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“…Methods using various strongly absorbing electrolyte co-ions such as pyridine [14], imidazole [15,16], cerium (III) ions [17] copper(II) ions [18], UV-CAT 1 [19], or benzimidazole [20], have been described. Various additives contained in the electrolyte (running buffer) have been used to vary the effective mobility of the analyte metal cations through fast complexation equilibria in the electrolyte [4,6].…”

Section: Introductionmentioning

confidence: 99%

“…Various additives contained in the electrolyte (running buffer) have been used to vary the effective mobility of the analyte metal cations through fast complexation equilibria in the electrolyte [4,6]. The numerous examples include crown ethers such as 18-crown-6 [17,20], hydroxy carboxylic acids and most importantly hydroxyisobutyric acid (HIBA) [19], or even polymeric complexing additives such as hydroxypropylmethylcellulose [15]. Varying the effective mobility of cations using these additives allowed governing separation selectivity and thus permitting separations of up to thirty cations in one run, which otherwise, based solely on the mobilities of their aquated ions, could not be separated.…”

Section: Introductionmentioning

confidence: 99%

“…The chemistry of the crown ethers was first reviewed in 1974 by Izatt [24] and they have been found to form primarily 1:1 metal:polyether complexes with a large amount of metal ions [25]. Since polyethers form complexes with hard cations [26], including alkali, alkaline earth and lanthanide ions, a selectivity enhancement can be expected for separations of these cations with crown ether present as an additive in the electrolyte [27][28][29][30][31]. Francois et al [21] investigated effects of the 18-crown-6 addition to the electrolyte and reported the best resolution with 2.5 mM 18-crown-6 for a sample composed of alkali, alkaline earth metal and ammonium cations.…”

Section: Introductionmentioning

confidence: 99%

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Capillary electrophoretic study of interactions of metal ions with crown ethers, a sulfated β-cyclodextrin, and zwitterionic buffers present as additives in the background electrolyte

2002

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Stability constants of K, Na, Ca, and Ba with 18-crown-6, K, Na, Li with sulfated beta-cyclodextrin and K, Li, Ca, Mg, Sr, and Ba ions with ([2-hydroxy-1,1-bis(hydroxymethyl) ethyl]-amino)-1-propanesulfonic acid (TAPS) were determined by capillary electrophoresis and computed using a general least squares minimizing program CELET. The results for 18-crown-6 agreed well with those evaluated by graphical methods or reported in the literature. Previously unknown stability constants of sulfated beta-cyclodextrins and TAPS determined for alkali and alkaline earth metals show that sulfated beta-cyclodextrin interacts with monovalent metals allowing to manipulate their effective mobility. It interacts stronger with divalent metal cations. TAPS, as zwitterionic buffer widely used in various analytical, biochemical and other applications, forms complexes with alkali and alkaline earth cations, and although the stability constants are rather low, the equilibria should be taken into account when TAPS is used and metal cations are present in solution at the same time.

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“…Da mesma maneira que na detecção indireta por absorção, a detecção indireta de fluorescência, utilizando-se um eletrólito com propriedades fluorescentes, como quinino e sulfato de cério (III), também pode ser utilizada 24 . A detecção por condutividade é um método sensível e universal de detecção, porém até o momento, o número de aplicações disponíveis na literatura não pode ser comparado aos citados anteriormente 25,26 .…”

Section: Detecção Na Análise De Cátionsunclassified

Determinação simultânea de cátions por eletroforese capilar: fundamentos e aplicações

Jager¹,

Tavares²

2001

Quím. Nova

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Recebido em 19/4/00; aceito em 16/10/00 SIMULTANEOUS DETERMINATION OF CATIONS BY CAPILLARY ELECTROPHORESIS: FUNDAMENTS AND APPLICATIONS. In this work, the analysis of cations by capillary electrophoresis is reviewed from the theoretical and practical point of view. Separation mechanisms and detection modes are discussed and illustrated. A thorough compilation of the literature over the last ten years, regarding applications of the technique to the analysis of cations in real matrices, is presented.Keywords: inorganic cations; capillary electrophoresis. Quim. Nova, Vol. 24, No. 3, 363-373, 2001. Revisão INTRODUÇÃOA eletroforese capilar é uma técnica instrumental de análise que utiliza essencialmente um capilar de sílica fundida, preenchido com uma solução de eletrólito. As extremidades do capilar estão imersas em reservatórios contendo eletrólito, aonde também estão colocados dois eletrodos de platina, conectados a uma fonte de alta tensão, para a aplicação da diferença de potencial. Um sistema de detecção e um dispositivo que permita a introdução da amostra no capilar também são necessários 1,2 . O interesse crescente pela técnica nos últimos anos promoveu o desenvolvimento de instrumentos comerciais dotados de sistemas sofisticados de injeção de amostra, detecção em linha e aquisição de dados, que tornam a técnica atraente para a utilização em análises de rotina.A principal vantagem da eletroforese capilar em relação às outras técnicas de separação é a maior eficiência e resolução obtidas em um tempo menor de análise e com a utilização de volumes pequenos da amostra (1 -10 nL por injeção) e do eletrólito de trabalho (10 -100 mL diários).Nesta técnica os compostos são separados com base na diferença entre as mobilidades iônicas, que estão relacionadas com a razão carga-massa, e a fatores estruturais. A mobilidade iônica pode ser calculada a partir de medidas de tempo de migração para o analito de interesse, além de outros parâmetros instrumentais, ou através dos valores de condutância equivalente, conforme as equações 1 e 2, respectivamente:onde µ i é a mobilidade iônica, L det é a distância da extremidade de injeção até a posição aonde está localizado o detector no capilar, L tot é o comprimento total do capilar, V é a diferença de potencial aplicada, t i é o tempo de migração do analito, µ osm é a mobilidade do fluxo eletroosmótico, λ equiv é a condutância equivalente da espécie iônica e F é a constante de Faraday. A mobilidade iônica é uma propriedade do soluto e está relacionada com a velocidade iônica e velocidade aparente pelas equações 3 e 4, respectivamente:A mobilidade do fluxo eletroosmótico é constante e depende das propriedades da solução como a constante dielétrica e viscosidade 1 . A velocidade do fluxo eletroosmótico é expressa pela equação 5: MECANISMOS DE SEPARAÇÃOEntre todas as possíveis aplicações da eletroforese capilar, a análise de cátions metálicos talvez tenha sido a que mais demorou para ser desenvolvida. A dificuldade inicial encontrada na otimização da separação de vários cátions metál...

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Indirect fluorimetric detection of alkali and alkaline earth metal ions in capillary zone electrophoresis with cerium(III) as carrier electrolyte

Cited by 80 publications

References 15 publications

Separation and determination of metal cations in milk and dairy products by CE

Separation and determination of metal cations in milk and dairy products by CE

Capillary electrophoretic study of interactions of metal ions with crown ethers, a sulfated β-cyclodextrin, and zwitterionic buffers present as additives in the background electrolyte

Determinação simultânea de cátions por eletroforese capilar: fundamentos e aplicações

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