Selectivity in reversed-phase separations

Neue, Uwe D.; O’Gara, John E.; Méndez, Alberto

doi:10.1016/j.chroma.2006.06.006

Cited by 111 publications

(63 citation statements)

References 90 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Recently, Neue published on a different approach towards capturing selectivity differences of packings [64]. The retention times of a large set of varied analytes, mostly pharmaceuticals, were measured under gradient conditions with methanol, MeCN, or THF as the organic modifier and at two pH values (acidic and neutral) for silica-based packings or at three pH values (acidic, neutral, and basic) for hybrid packings using MS detection.…”

Section: General Characterization Methods For Stationary Phasesmentioning

confidence: 99%

Stationary phase characterization and method development

Neue

2007

J of Separation Science

Self Cite

View full text Add to dashboard Cite

The properties of stationary phases and their characterization methods are reviewed. New and significant developments have occurred in the last few years, and new methods for stationary phase characterization have become available. The characterization methods are discussed, and the differences between the different methods are pointed out. In addition, method development approaches are reviewed, with special emphasis on recent developments that employ multiple parameters in parallel. Also, the renewed interest of temperature as a tool in method development is surveyed.

show abstract

Section: General Characterization Methods For Stationary Phasesmentioning

confidence: 99%

Stationary phase characterization and method development

Neue

2007

J of Separation Science

Self Cite

View full text Add to dashboard Cite

show abstract

“…67 Mais especificamente, nas separações por CLAE, a seletividade é influenciada por quatro variáveis: a fase estacionária; a composição da fase móvel; as condições físicas (temperatura e pressão) e, a natureza dos compostos a serem analisados.…”

Section: Avanços Na Seletividade Das Fases Estacionárias Modernasunclassified

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

Maldaner¹,

Jardim²

2010

Quím. Nova

View full text Add to dashboard Cite

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....

show abstract

“…Although polar endcapped and polar embedded group phases contain polar groups in within the stationary phase, they still generally exhibit RP selectivity [1][2][3][4][5]. That is, separations using polar endcapped and polar embedded group phases are often on the basis of solute polarity, with polar solutes eluting earlier and nonpolar solutes being retained longer (when an isocratic mobile phase is used).…”

Section: Introductionmentioning

confidence: 99%

“…A recent trend in RPLC has been the introduction of stationary phases containing a polar functional group in addition to the nonpolar RP ligand [1][2][3][4][5][6][7][8]. In general, two types of RP stationary phases have been developed: polar endcapped phases, in which a polar group is used as an endcapping reagent after derivatization with a nonpolar ligand, and polar embedded group phases, in which a polar functional group is located within the alkyl chain itself.…”

Section: Introductionmentioning

confidence: 99%

Comparison of retention on traditional alkyl, polar endcapped, and polar embedded group stationary phases

Coym¹

2008

J of Separation Science

View full text Add to dashboard Cite

Comparison of retention on traditional alkyl, polar endcapped, and polar embedded group stationary phasesThe development of new RP stationary phases containing polar groups has provided the chromatographer with a variety of stationary phase choices with differing selectivities. Polar endcapped and polar embedded group stationary phases have found use in solving a wide variety of separation problems, especially for the efficient separation of organic bases as well as separations necessitating the use of highly aqueous mobile phases. In this report, the retention thermodynamics of small, nonpolar solutes on traditional alkyl, polar endcapped, and polar embedded group stationary phases are compared. It is found that the nonpolar (methylene) transfer enthalpy is less favorable when polar embedded group phases are used, when compared to traditional or polar endcapped phases. In contrast, the transfer enthalpy of a phenyl group is found to be more favorable when a polar endcapped phase is used. In addition, the retention characteristics of these phases are compared using a set of solutes with differing solvatochromic parameters. Hydrogen-bond acids appear to have enhanced retention on polar embedded group phases, while hydrogen-bond bases have enhanced retention on polar endcapped phases.

show abstract

Selectivity in reversed-phase separations

Cited by 111 publications

References 90 publications

Stationary phase characterization and method development

Stationary phase characterization and method development

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

Comparison of retention on traditional alkyl, polar endcapped, and polar embedded group stationary phases

Contact Info

Product

Resources

About