Two-dimensional liquid chromatography with mixed mode stationary phases

Venkatramani, Cadapakam J.; Zelechonok, Yury

doi:10.1016/j.chroma.2004.11.103

Cited by 34 publications

(21 citation statements)

References 18 publications

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“…Thus, there is a continuous flow of mobile phase through the primary and secondary column throughout the separation. Use of dual pumps will eliminate the need for splitting the mobile phase at union U1 and provide independent control of mobile phase flow and composition in the two dimensions (if desired), as discussed in our earlier work [25]. With a single pump, one is limited to the same mobile phase composition in both dimensions.…”

Section: Chromatographic Equipmentmentioning

confidence: 96%

“…Details of selectivity tuning can be found in our earlier work on 2-D-GC and is not the scope of this article [8,24]. Later we exploited differences in the interaction mechanisms of mixed mode columns to realize complementary 2-D-LC separation [25]. However, in both these studies, approximately twenty to forty percent of the primary column eluate was transferred to the secondary column and hence the separation was not comprehensive.…”

Section: Introductionmentioning

confidence: 96%

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Towards a comprehensive 2‐D‐LC–MS separation

Venkatramani¹,

Patel

2006

J of Separation Science

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A comprehensive 2-D-LC-MS method has been developed by coupling columns of different selectivity. The primary column eluate is alternately trapped and sampled onto the secondary columns through a guard column interface. When one guard column traps the eluate, the other injects the previously trapped components onto a secondary column. This cycle is repeated throughout the chromatogram. The use of dual secondary columns provides the secondary columns with additional time to generate high-speed chromatograms. Each secondary column generates alternate chromatograms which when combined generate the entire chromatogram. The primary column separation is comparable to conventional HPLC, whereas the secondary column separation is fast. With both the columns operating in reverse phase mode, one would expect strong correlation in the two-dimensional retention and hence inefficiency in separation. However, differences in column operation modes, interaction mechanisms, and vendor silica result in a complementary separation. The system was evaluated by comparing it to one-dimensional counterparts and coupled column chromatography. Although some correlations were observed in 2-D-LC-MS, peaks do show two-dimensional distribution with superior UV and MS data as co-elution is minimized. Also, the ease of converting conventional systems to 2-D-LC-MS is discussed.

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Section: Chromatographic Equipmentmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 96%

Towards a comprehensive 2‐D‐LC–MS separation

Venkatramani¹,

Patel

2006

J of Separation Science

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“…Mixed-mode HPLC can be achieved by connecting two columns with an ODS and a cation-exchange stationary phase [38], by packing two types of stationary phases, reversed phase and ionexchange, in a column [39,40], and by chemically binding an ionizable group in an alkyl chain on a silica-based support [41,42]. The preparation of the heat-treated metal-silica gel developed in this study is very simple.…”

Section: Effect Of the Metal Typementioning

confidence: 98%

Selective retention of basic compounds by metal aquo-ion affinity chromatography

Asakawa¹,

Yamamoto

Asakawa

2014

J. Sep. Science

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A novel metal aquo-ion affinity chromatography has been developed for the analysis of basic compounds using heat-treated silica gel containing hydrated metal cations (metal aquo-ions) as the packing material. The packing materials of the metal aquo-ion affinity chromatography were prepared by the immobilization of a single metal component such as Fe(III), Al(III), Ag(I), and Ni(II) on silica gel followed by extensive heat treatment. The immobilized metals form aquo-ions to present cation-exchange ability for basic analytes and the cation-exchange ability for basic analytes depends on pKa of the immobilized metal species. In the present study, to evaluate the retention characteristics of metal aquo-ion affinity chromatography, the on-line solid-phase extraction of drugs was investigated. Obtained data clearly evidence the selective retention capability of metal aquo-ion affinity chromatography for basic analytes with sufficient capacity.

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“…Estas FE vêm sendo também usadas com sucesso como a segunda coluna em cromatografia líquida bidimensional. 104,106,107,112 Cabe ressaltar que existe uma controvérsia entre os fabricantes referente à denominação das FE de modo misto e das de interação hidrofílica, que serão apresentadas a seguir, uma vez que ambas podem ser empregadas no modo de separação de interação hidrofílica. Entretanto, a diferença básica entre elas reside no fato que as FE de modo misto são empregadas principalmente para a separação de compostos ionizáveis, enquanto que as FE de interação hidrofílica são aplicadas na análise de compostos moleculares.…”

Section: Fases Estacionárias De Modo Mistounclassified

Fases estacionárias modernas para cromatografia líquida de alta eficiência em fase reversa

Maldaner¹,

Jardim²

2010

Quím. Nova

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Recebido em 15/12/09; aceito em 1/4/10; publicado na web em 29/6/10 MODERN STATIONARY PHASES FOR REVERSED PHASE HIGH PERFORMANCE LIQUID CHROMATOGRAPHY. This review first discusses the limitations of many of the supports and stationary phases used in reversed phase high performance liquid chromatography and then describes those, developed more recently, that present better stabilities and more versatile selectivities. Emphases will be given to stationary phases that use higher purity silicas, hybrid silicas, monolithic silicas, metallic oxides and mixed oxides as supports and those that have embedded polar groups or contain phenyl or fluoro groups as the stationary phase as well as the phases used for mixed mode or hydrophilic interaction separations. These modern stationary phases facilitate the analysis of complex mixtures.Keywords: RP-HPLC; modern stationary phases; stability. INTRODUÇÃOO alto nível de desenvolvimento e expansão alcançado pela cromatografia líquida de alta eficiência em fase reversa (CLAE-FR), ao longo das últimas décadas, deve-se principalmente a sua vasta aplicabilidade, que engloba o desenvolvimento de novos produtos, o controle da qualidade desses produtos e, também, as possíveis contaminações provenientes desses produtos e dos disponíveis no mercado há anos. Dentro deste contexto estão envolvidas as indústrias farmacêuticas, alimentícias, agropecuárias e químicas, as agências reguladoras que tratam do meio ambiente e outras. A ampla aplicabilidade da CLAE-FR foi o que impulsionou e continua impulsionando as pesquisas em busca do aprimoramento desta técnica, principalmente referente ao desenvolvimento de novas fases estacionárias (FE). Hoje a CLAE-FR pode ser considerada uma técnica de análise (separação, confirmação e quantificação) bem difundida e empregada, em consequência das colunas cromatográficas e equipamentos de alta tecnologia que se encontram disponíveis.As FE empregadas em CLAE-FR consistem de uma camada orgânica apolar ligada quimicamente ou imobilizada ou apenas sorvida a um suporte cromatográfico. A forma de obtenção dessas camadas apolares e a variedade de óxidos empregados como suportes cromatográficos resultam nos diferentes tipos de FE. O método mais comum e também o mais empregado para a obtenção das FE consiste na introdução de monocamadas orgânicas através de reações com reagentes apropriados, que dá origem às fases estacionárias quimicamente ligadas (FEQL).1-4 As FEQL podem ser obtidas por diferentes processos, como esterificação, cloração seguida por reação com reagente de Grignard ou com compostos organo-lítio e organossilanização. Uma forma alternativa de preparo de FE é o método de recobrimento do suporte com polímeros orgânicos, que pode ser realizado de duas maneiras: mistura de um polímero pré-sintetizado de composição química bem definida em solução com o suporte e posterior evaporação do solvente e, polimerização in situ de uma solução de monômeros ou oligômeros, iniciada ou propagada na superfície do suporte, geralmente seguida de uma etapa de imobilização....

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Two-dimensional liquid chromatography with mixed mode stationary phases

Cited by 34 publications

References 18 publications

Towards a comprehensive 2‐D‐LC–MS separation

Towards a comprehensive 2‐D‐LC–MS separation

Selective retention of basic compounds by metal aquo-ion affinity chromatography

Fases estacionárias modernas para cromatografia líquida de alta eficiência em fase reversa

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