Atypical silica-based column packings for high-performance liquid chromatography

Kirkland, J. J.; Truszkowski, F.A; Ricker, Robert D.

doi:10.1016/s0021-9673(01)01339-5

Cited by 43 publications

(18 citation statements)

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“…No início da cromatografia líquida pressurizada, por volta dos anos 60, [15][16][17] eram empregadas partículas de sílica porosa de forma irregular e com grande distribuição de tamanho, na faixa de 40-50 µm, com as quais se realizava a cromatografia em fase normal (FN). A forma de obtenção dessas partículas era basicamente a moagem de partículas maiores como, por exemplo, grumos de xerogel, e posterior classificação por tamanho com o uso de peneiras com abertura regulável.…”

Section: Sílica Modernaunclassified

“…[15][16][17][18][19] A uniformidade da forma e o tamanho das partículas propiciaram colunas melhores recheadas que resultaram no aumento de eficiência e de resolução. Para a obtenção dessas partículas, diferentes rotas de síntese foram empregadas: dispersões da sílica coloidal e geleificação num sistema de duas fases; hidrólise e policondensação de polietoxissiloxano (PES) em esferas de sílica hidrogel por agitação, em um sistema de duas fases (processo sol-gel); aglutinação de soluções coloidais de sílica na presença de polímero seguido de calcinação das esferas; secagem por vaporização de suspensões coloidais de sílica e, formação e crescimento de nano partículas de sílica em suspensões.…”

Section: Sílica Modernaunclassified

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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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Section: Sílica Modernaunclassified

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

Maldaner¹,

Jardim²

2010

Quím. Nova

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“…[12][13][14][15] Compared with the ultra-fast HPLC system described above, the new separation media show a different chromatographic behavior because their structural characteristics, i.e., shapes and porosities, are extremely different from those of the super-fine full-porous spherical particles. For example, in the case of shell-type particles, which consist of an inert center core and a superficial porous shell layer, the following three points can be picked up as their advantageous characteristics.…”

Section: Introductionmentioning

confidence: 99%

“…[23][24][25][26][27][28][29][30][31][32] Important information about the retention equilibrium and mass transfer kinetics in the column can be obtained from the elution peak profiles. Moment equations theoretically explain how the first absolute moment (μ1) and the second central moment (μ2′) of the elution peaks are correlated with several parameters of the retention equilibrium, mass-transfer rate, and reaction kinetics with physically justifications.Recently, various packing materials having different structural characteristics, i.e., shapes and porosities, have been developed to achieve fast separation with high efficiency, for example, monolith, 9-11 core-shell particles, [12][13][14][15] and polymer fiber stationary phases. 33 Chromatographic behavior of the new types of separation media must be accurately analyzed by using the adequate rate equations, which correspond to their structural characteristics.…”

mentioning

confidence: 99%

“…Recently, various packing materials having different structural characteristics, i.e., shapes and porosities, have been developed to achieve fast separation with high efficiency, for example, monolith, 9-11 core-shell particles, [12][13][14][15] and polymer fiber stationary phases. 33 Chromatographic behavior of the new types of separation media must be accurately analyzed by using the adequate rate equations, which correspond to their structural characteristics.…”

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Moment Equations for Chromatography Using Superficially Porous Spherical Particles

Miyabe

2011

ANAL. SCI.

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IntroductionHigh-performance liquid chromatography (HPLC) has been extensively used as one of the most powerful separation techniques in the field of fine chemistry and biological science. 1 Still, however, it is now strongly required to develop a faster separation system with a high throughput. There are two major approaches for achieving the demand of the times. One is the development of an ultra-fast HPLC system consisting of a column packed with super-fine full-porous spherical particles and a special pump apparatus for delivering the mobile-phase solvent into the column under high-pressure conditions. [2][3][4] However, this approach is accompanied by new problems because the separation conditions are remarkably changed from those for conventional HPLC. Chromatography is carried out under much a faster flow velocity, hence, under extremely higher pressure conditions. The friction of the mobile phase against the packed bed of the super-fine particles leads to the generation of heat. The resulting temperature distribution taking place in both the axial and radial directions of the column provides an unfavorable influence on the peak profile, and hence on the column efficiency. [5][6][7][8] There would be a paradoxical limitation in this approach. Although the separation speed can be amplified with an increase in the mobile-phase flow velocity, the influence of the heterogeneous temperature distribution on the column efficiency must be emphasized. This is an additional problem of the ultra-fast HPLC technique, which can substantially be neglected under conventional HPLC conditions.An alternative is the development of new types of separation media, such as monoliths [9][10][11] and shell-type spherical particles. [12][13][14][15] Compared with the ultra-fast HPLC system described above, the new separation media show a different chromatographic behavior because their structural characteristics, i.e., shapes and porosities, are extremely different from those of the super-fine full-porous spherical particles. For example, in the case of shell-type particles, which consist of an inert center core and a superficial porous shell layer, the following three points can be picked up as their advantageous characteristics. At first, the whole particle size is relatively large. This is effective for preventing any unnecessary elevation of the column back pressure under high flow rate conditions. The size of interparticulate channels in a column packed with spherical particles depends on the particle diameter and their packing density. It is usually estimated to be about one third of the particle diameter, 16 and cannot independently be controlled. Second, the thickness of the superficial porous shell layer is sufficiently thin. It has been well recognized that the column efficiency under high flow-rate conditions primarily rests on the mass-transfer resistance in the stationary phase and that the reduction in the diffusion distance of sample molecules is effective for suppressing band broadening due to intra-stationary phas...

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Gradient Elution

Snyder

Kirkland

Dolan

2009

Introduction to Modern Liquid Chromatography

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Atypical silica-based column packings for high-performance liquid chromatography

Cited by 43 publications

References 11 publications

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

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

Moment Equations for Chromatography Using Superficially Porous Spherical Particles

Gradient Elution

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