Controlled changes of selectivity in the separation of ions by capillary electrophoresis

Jones, William; Jandík, Petr

doi:10.1016/s0021-9673(01)93043-2

Cited by 310 publications

(101 citation statements)

References 8 publications

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“…8 As shown in Fig. 1, migration times for oxalate and nitrate were prolonged because the sodium sulfate concentration was increased from 15 to 50 mM.…”

Section: Simple Capillary Electrophoretic Determination Of Soluble Oxmentioning

confidence: 89%

Simple Capillary Electrophoretic Determination of Soluble Oxalate and Nitrate in Forage Grasses

2003

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A simple capillary electrophoretic method is described for the simultaneous determination of soluble oxalate and nitrate in forage grasses. Grass samples were ground and extracted with water. The extracts were filtered and submitted to capillary electrophoresis. Electrophoresis was performed in a 75 μm ×50 cm fused silica capillary with 30 mM sodium sulfate containing an electroosmotic flow modifier under constant voltage at —8 kV Separated oxalate and nitrate were detected with direct UV absorption at 214 nm. The present method can be used for routine monitoring of the concentration of soluble oxalate and nitrate in grasses.

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“…8 As shown in Fig. 1, migration times for oxalate and nitrate were prolonged because the sodium sulfate concentration was increased from 15 to 50 mM.…”

Section: Simple Capillary Electrophoretic Determination Of Soluble Oxmentioning

confidence: 89%

Simple Capillary Electrophoretic Determination of Soluble Oxalate and Nitrate in Forage Grasses

2003

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“…Várias abordagens têm sido propostas para otimização das condições de análise de ânions por eletroforese capilar 11,[15][16][17][79][80][81][82][83][84][85][86][87] . Embora muitos destes trabalhos apresentem estudos fragmentados sobre o efeito parcial de algumas variáveis do sistema, todos fornecem informações fundamentais para subsidiar o desenvolvimento de metodologia adequada, como requerem amostras de matrizes complexas, por exemplo, e são satisfatórios em uma dada extensão.…”

Section: Comentários Finaisunclassified

“…Nestes trabalhos as técnicas são avaliadas com relação a diversos aspectos. Talvez o mais importante seja a eficiência da coluna, que se reflete na capacidade de pico (número máximo de solutos separados numa única corrida) 15 . A figura 1 ilustra este aspecto em particular, na separação de 36 ânions por eletroforese capilar e cromatografia iônica, mostrando de forma inequívoca o alto desempenho da coluna capilar.…”

Section: Introductionunclassified

Determinação simultânea de ânions por eletroforese capilar: características e aplicações

Colombara¹,

Tavares²,

Massaro³

1997

Quím. Nova

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Recebido em 20/11/96; aceito em 22/03/97 SIMULTANEOUS DETERMINATION OF ANIONS BY CAPILLARY ELECTROPHORESIS:CHARACTERISTICS AND APPLICATIONS. Capillary electrophoresis (CE) encompasses a number of characteristics quite suitable for the simultaneous analysis of small ions such as high efficiency and resolving power, directly associated to its impressively high peak capacity, and short analysis time. In appropriate conditions, it is possible to perform the separation of approximately 36 anions in less than 3 minutes. In this work, the mechanisms by which anion analysis is performed was criteriously discussed, and a thorough review of the literature in the past 5 years, focusing mostly in applications of CE to anion analysis in real matrices, was presented.Keywords: capillary electrophoresis; ion analysis; anion. REVISÃO INTRODUÇÃOA determinação analítica de ânions encontra extensa aplicação em vários segmentos da indústria (química, farmacêutica, alimentícia, etc.), bem como na caracterização de amostras biológicas e ambientais 1 . A análise individual de ânions pode ser feita por métodos volumétricos, gravimétricos, espectrofotomé-tricos e eletroanalíticos 2,3 . Já para análise simultânea de ânions, geralmente são empregados métodos cromatográficos [3][4][5] . A cromatografia iônica (CI) 4 com detecção condutométrica é empregada principalmente para ânions inorgânicos e alguns orgâni-cos de cadeia curta, enquanto que, para os ânions derivados de ácidos orgânicos de cadeias maiores, é utilizada a cromatografia líquida de alta eficiência (CLAE) 5 . Na última década, a eletroforese capilar (EC) 6 vem sendo apontada como uma alternativa bastante atraente para a determinação simultânea de ânions. Ela tem se distinguido das demais técnicas utilizadas para o mesmo fim, principalmente no que se refere à versatilidade e simplicidade. Existem inúmeros trabalhos de comparação na literatura, tanto de EC versus CI, especificamente 7-11 , quanto de EC versus CLAE 12-14 . Nestes trabalhos as técnicas são avaliadas com relação a diversos aspectos. Talvez o mais importante seja a eficiência da coluna, que se reflete na capacidade de pico (número máximo de solutos separados numa única corrida) 15 . A figura 1 ilustra este aspecto em particular, na separação de 36 ânions por eletroforese capilar e cromatografia iônica, mostrando de forma inequívoca o alto desempenho da coluna capilar. Os demais aspectos são: custo e durabilidade das colunas 16,17 , necessidade de tratamento prévio da amostra, tempo de análise 18 , volume de amostra 19 , e custo final por análise 20 . A conclusão que prevalece nestes estudos é que a eletroforese capilar apresenta inúmeras vantagens, o que tem contribuído para assegurar uma posição de destaque entre as técnicas analíticas de separação. CARACTERÍSTICAS DA ANÁLISE DE ÂNIONSA separação e identificação de ânions por eletroforese capilar é em geral conduzida em soluções aquosas de eletrólitos, contendo ânions cromóforos e agentes modificadores da superfí-cie capilar. A presença do cromóforo só se faz ne...

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Section: Introductionmentioning

confidence: 99%

“…Selection of an acidic migrating solution is one answer and the EOF will be reduced with the migrating solution. Since cationic surfactants are used to form bi-layers by the dynamic coating of the capillary [1][2][3] and the EOF is reversed as a result, a surface-refining reagent is indispensable in the CZE separation of anionic species.In addition to the cationic surfactants, cationic polyelectrolytes are promising alternatives to reverse the direction of the EOF; poly(1,1-dimethyl-3,5-dimethylenepiperidinium) chromate, hexadimethrine chromate, poly(1,1-dimethyl-3,5-dimethylenepyrrolidinium) chromate, diethylaminoethyl dextran chromate were used as such polyelectrolytes, and the analyte anions were indirectly detected with chromate ions. 4 The cationic polyelectrolytes play an additional role to work as interacting reagent with the analyte anions.…”

mentioning

confidence: 99%

Chitosan as Cationic Polyelectrolyte for the Modification of Electroosmotic Flow and Its Utilization for the Separation of Inorganic Anions by Capillary Zone Electrophoresis

Takayanagi

Motomizu

2006

ANAL. SCI.

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IntroductionIn the analysis of anionic species by capillary zone electrophoresis (CZE), control of the direction and speed of the electroosmotic flow (EOF) is essential, because the direction of the electrophoretic migration of anions is opposite to that of the EOF, when a usual fused silica capillary is used. When the analyte anions possessing large electrophoretic mobility, such as inorganic anions, are supposed to be detected, the electrophoretic mobility of the analytes is larger than the EOF or almost equivalent to it at alkaline solution, and it takes a longer separation time even using the reversal of the electric field. Therefore, the speed of the EOF is usually suppressed or reversed for the analysis of anionic species. Selection of an acidic migrating solution is one answer and the EOF will be reduced with the migrating solution. Since cationic surfactants are used to form bi-layers by the dynamic coating of the capillary [1][2][3] and the EOF is reversed as a result, a surface-refining reagent is indispensable in the CZE separation of anionic species.In addition to the cationic surfactants, cationic polyelectrolytes are promising alternatives to reverse the direction of the EOF; poly(1,1-dimethyl-3,5-dimethylenepiperidinium) chromate, hexadimethrine chromate, poly(1,1-dimethyl-3,5-dimethylenepyrrolidinium) chromate, diethylaminoethyl dextran chromate were used as such polyelectrolytes, and the analyte anions were indirectly detected with chromate ions. 4 The cationic polyelectrolytes play an additional role to work as interacting reagent with the analyte anions. Haddad and his coworkers investigated the ion-exchange mechanism in the CZE separation by simulation and practical resolution improvement, and they proposed ion chromatography-capillary electrophoresis. 5,6 Electrophoretic mobility of some organic anions was reduced by ion-exchange with poly(diallyldimethylammonium)phthalate background electrolyte, and the selectivity among the anions were also developed.Chitosan, an N-deacetylation product of chitin, is one of the useful cationic polyelectrolytes, and has several characteristics such as being made of relatively hydrophilic saccharine groups, safe and biodegradable materials present in nature. Chitosan is soluble in acidic solution with the protonation of the amino groups (pKa = 6.5). 7 Chitin and chitosan oligosaccharides were separated and detected by capillary zone electrophoresis after derivatization with 8-aminopyrene-1,3,6-trisulfonic acid. 8 High-molecular chitosan was also analyzed by CZE. 9 Chitosan has also been used as coating material on fused silica capillary for the separation of basic proteins, 10 and coupled chitosan has been used for both basic and acidic proteins. 11In this study, chitosan as a cationic polyelectrolyte was used to reverse the EOF by dynamic coating of the capillary innerwall, and the capillary was used for the separation of inorganic anions. The interactions with analyte anions were also investigated through the changes in electrophoretic mobility of some ino...

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Controlled changes of selectivity in the separation of ions by capillary electrophoresis

Cited by 310 publications

References 8 publications

Simple Capillary Electrophoretic Determination of Soluble Oxalate and Nitrate in Forage Grasses

Simple Capillary Electrophoretic Determination of Soluble Oxalate and Nitrate in Forage Grasses

Determinação simultânea de ânions por eletroforese capilar: características e aplicações

Chitosan as Cationic Polyelectrolyte for the Modification of Electroosmotic Flow and Its Utilization for the Separation of Inorganic Anions by Capillary Zone Electrophoresis

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