Elevated temperature and temperature programming in conventional liquid chromatography – fundamentals and applications

Vanhoenacker, Gerd; Sandra, Pat

doi:10.1002/jssc.200600160

Cited by 101 publications

(58 citation statements)

References 103 publications

(66 reference statements)

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“…increase and the resistance to mass transfer (C-term) will decrease [25]. The net effect is a shift of the minimum in the van Deemter equation towards higher flow rates and a reduced plate height at flow rates above the minimum in the van Deemter equation [26].…”

Section: Effect Of Temperature On Peak Capacitymentioning

confidence: 99%

Maximizing peak capacity and separation speed in liquid chromatography

Petersson¹,

Frank

Heaton

et al. 2008

J of Separation Science

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The practical effects of gradient time and flow rate on the peak capacities of a range of analytes of differing molecular weights (MWs) and physico-chemical properties have been evaluated using ultra high pressure LC instrumentation with sub-2 lm and superficially porous particle phases. Optimum peak capacity, in RP gradient LC, for small molecules, including typical pharmaceutical drugs and peptides with MWs up to 1300, was demonstrated at a maximum flow rate for a given gradient time (i.e. up to 40 min). Flow rates significantly higher than the optimum in the van Deemter plots and also higher than those typically employed by the majority of the chromatographers today are recommended for gradient LC (i.e. up to 1.0 mL/min on 50 -15062.1 mm 1.7 lm columns). This recommendation is applicable for temperatures above 408C, i.e. temperatures typically utilized for separations employing sub-2 lm particles to reduce column back pressure. Van Deemter and pseudo van Deemter plots were determined and combined with chromatographic gradient elution theory to explain our unexpected observations. The derived models exhibited good agreement between experimental and predicted peak capacities (absolute average error 4%, max. error 12%).

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Section: Effect Of Temperature On Peak Capacitymentioning

confidence: 99%

Maximizing peak capacity and separation speed in liquid chromatography

Petersson¹,

Frank

Heaton

et al. 2008

J of Separation Science

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“…Entretanto, o uso em conjunto de um gradiente de FM e de temperatura possibilitou a separação dos 20 solutos. 36 …”

Section: Influência Da Temperatura Sobre a Resoluçãounclassified

“…Quando maiores esta diferença 34,36,43 No entanto, qualquer afirmação quanto à melhoria da detecção em função do aumento da temperatura dever ser cautelosa. A resposta do detector de massas aumenta quando a composição da FM é mantida constante.…”

Section: 57unclassified

Possibilidades e limitações no uso da temperatura em cromatografia líquida de fase reversa

Borges¹,

Bottoli²

2010

Quím. Nova

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Recebido em 16/9/09; aceito em 30/11/09; publicado na web em 8/4/10 POSSIBILITIES AND LIMITATIONS OF USING TEMPERATURE IN REVERSED PHASE LIQUID CHROMATOGRAPHY. High-temperature liquid chromatography (HTLC) is a technique that presents a series of advantages in liquid phase separations, such as: reduced analysis time, reduced pressure drop, reduced asymmetry factors, modified retentions, controlled selectivities, better efficiencies and improved detectivities, as well as permitting green chromatography. The practical limitations that relate to instrumentation and to stationary phase instability are being resolved and this technique is now ready to be applied for routine determinations.Keywords: high temperature liquid chromatography; stationary phase stability; green chromatography. INTRODUÇÃOO termo alta temperatura em cromatografia líquida (High Temperature Liquid Chromatography, HTLC) se refere ao uso de temperaturas entre 40 a 200 o C. O uso da temperatura como variável em cromatografia líquida é recente, embora Antia e Horvath 1 tenham descrito seu uso em 1988. A principal vantagem desta técnica é a redução no tempo de análise, característica que é de grande interesse prático para os usuários de cromatografia. Mas até o momento, esta técnica reside quase exclusivamente no meio acadêmico por causa de algumas limitações, como a falta de instrumentação específica para tal fim e a instabilidade das fases estacionárias. Desta forma, esta revisão se dedica à discussão das vantagens e limitações desta técnica, bem como os avanços recentes quanto à instrumentação e fases estacionárias, os quais devem impulsionar a migração desta técnica para o meio industrial. ASPECTOS TEÓRICOS Influência da temperatura sobre a pressãoA pressão gerada pela passagem de fase móvel (FM) por uma coluna pode ser descrita pela equação de Kozeny-Carman:2,3 ΔP = (ηFL)/(K 0 πr 2 dp 2 ), onde K 0 é a permeabilidade específica, η é a viscosidade da FM, F é a vazão da FM, r é o raio interno da coluna e dp é o diâmetro médio das partículas da fase estacionária (FE) que recheiam a coluna. A viscosidade decresce exponencialmente em função da temperatura, 2,3 assim, o aumento da temperatura permite: a utilização de maiores vazões; o emprego de partículas com menores diâmetros; a utilização de colunas com maior comprimento ou conectadas em série.Um exemplo de como o aumento da temperatura permite o uso de maiores vazões é o trabalho de Yang et al.2 onde uma coluna ZirChrom-PS (50 x 4,6 mm, dp 2,5 μm) utilizada a 25 o C e com FM acetonitrila:água, 25:75 v/v, a uma vazão de 2 mL/min gera uma pressão de 400 bar, alcançando o limite máximo de pressão de um sistema convencional de cromatografia líquida de alta eficiência (High Performance Liquid Chromatography, HPLC). Quando a temperatura é elevada a 150 o C, a pressão é reduzida a 60 bar, permitindo o uso de uma vazão de 14 mL/min sem exceder o limite de pressão da bomba.As micropartículas (dp < 2 μm) têm pequena resistência à transferência de massa a altas vazões. Por isso podem ser utilizadas com pouc...

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“…The only additional requirement is an appropriate mobile phase and column heating system [20,[22][23][24]. The use of elevated column temperatures in RP-LC to achieve high separation efficiencies have been investigated extensively [5,[25][26][27][28][29][30] …”

Section: Introductionmentioning

confidence: 99%

High-efficiency hydrophilic interaction chromatography by coupling 25cm×4.6mm ID×5μm silica columns and operation at 80°C

Louw

Lynen

Hanna-Brown

et al. 2010

Journal of Chromatography A

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Recently, hydrophilic interaction chromatography (HILIC) has emerged as a valuable orthogonal tool to reversed-phase liquid chromatography (RP-LC) as it allows for resolution of highly polar ionisable compounds. The relationships between separation efficiency, column length and speed of analysis for 4.6 mm ID x 5 µm silica particle columns in HILIC are demonstrated using kinetic plots. The kinetic plots constructed for conventional pressure systems operating at 350 bar and at 30 o C and 80°C are confirmed using experimental data for different column lengths. Efficiencies of more than 130,000 theoretical plates could be achieved by connecting up to six columns of 25 cm. As expected, a significant gain in analysis speed without loss of efficiency could be obtained by operating at 80°C compared to 30°C. The advantages of using long columns in HILIC in combination with elevated column temperature for the pharmaceutical industry are illustrated using test mixtures comprised of commercially available ionisable compounds (including some containing functional groups with potential genotoxic typical structural alerts) as well as real polar ionisable pharmaceuticals. Keywords:Hydrophilic interaction liquid chromatography, high efficiency, kinetic plots, temperature, speed 3 Correspondence:Professor Pat Sandra, Ghent University, Krijgslaan 281 S4-bis, B-9000, Ghent, Belgium E-mail: pat.sandra@richrom.comTel: +32 56 204031; Fax: +32 56 204858 IntroductionReversed-phase liquid chromatography (RP-LC) is by far the most widely employed analytical tool in drug discovery and development. In recent years, the efficiency of RP-LC has been drastically increased through various approaches including using sub-2µm particles in combination with ultra high pressure LC (UHPLC) [1][2][3], increasing the column length and operation at elevated temperature (ETLC) [4][5][6] or by combining both UHPLC and ETLC [7,8].These developments have certainly facilitated the development of generic methodologies for RP-LC for separations of active pharmaceutical ingredients (API's) and impurities [5].Furthermore, these advances have helped separation scientists to exploit early fundamental theories around the principles of separation optimisation with respect to efficiency and speed by utilisation of kinetic plots. For the pharmaceutical industry, which will certainly still have a plethora of conventional HPLC instrumentation in its good manufacturing practice (GMP) laboratories, kinetic plots can certainly serve a purpose in directing how conventional instrumentation and columns can be used more appropriately in combination with ETLC and long columns. This can help to optimize the use of conventional particle diameters (5 µm) to yield either maximum efficiency and to compared to sub-2µm particles, or to increased the speed of analysis.Since these developments, a chromatographic technique that has been enjoying recent attention in the pharmaceutical industry is hydrophilic interaction chromatography (HILIC).HILIC has become a valuable addition t...

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Elevated temperature and temperature programming in conventional liquid chromatography – fundamentals and applications

Cited by 101 publications

References 103 publications

Maximizing peak capacity and separation speed in liquid chromatography

Maximizing peak capacity and separation speed in liquid chromatography

Possibilidades e limitações no uso da temperatura em cromatografia líquida de fase reversa

High-efficiency hydrophilic interaction chromatography by coupling 25cm×4.6mm ID×5μm silica columns and operation at 80°C

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