Practice and theory of high temperature liquid chromatography

Abstract

Review Practice and theory of high temperature liquid chromatographyHigh temperature liquid chromatography (HTLC) exists in a temperature region beyond ambient (ca. 408C) and below super critical temperatures. The promises of HTLC, such as increased analysis speed, enhanced separation productivity, "green" LC with pure water mobile phases coupled to universal FID detection, and fast analysis of complex samples by combination with fast 2-D techniques, have become an option for routine practice. The focus of this paper is to review the key developments that have made the application of HTLC a practical technique and draw attention to new developments in 2-D techniques that incorporate HTLC that offer an opportunity to vastly increase the usefulness of HPLC for the analysis of complex samples.

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

“…Os sistemas de HTLC são semelhantes aos sistemas convencionais de HPLC, exceto pela necessidade de pré-aquecer a FM na temperatura do forno para evitar gradientes indesejáveis de temperatura, utilizando uma serpentina de pré-aquecimento entre a coluna e o injetor, e de resfriar a FM antes que ela alcance o detector, quando este não é compatível com altas temperaturas, 3,17,43,55 utilizando um tubo de resfriamento entre a coluna e o detector (Um esquema de um sistema para HTLC é descrito na Figura 3S, material suplementar).…”

“…O comprimento necessário da serpentina entre o injetor e a coluna é uma função da vazão e da temperatura empregada, 3,55 sendo que quanto maior a vazão e a temperatura utilizada maior será o comprimento da serpentina. Por outro lado, quanto maior a serpentina maior será a dispersão e a pressão gerada no sistema, sendo que o mesmo raciocínio se aplica ao tubo de resfriamento.…”

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

“…The relationship is described by the Van 't Hoff equation [22,41]. Because retention is an exothermic process (∆H < 0) and generally entropy is lost upon transfer from the mobile to the stationary phase (∆S < 0), an increase in temperature leads to a shift of the equilibrium towards the mobile phase and therefore to a drop in retention [27,31,40,41]. Overall, however, the retention of the test compounds is relatively low at 80°C (k API <2.3).…”

“…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] …”

High-temperature liquid chromatography of steroids on a bonded hybrid column

“…[1][2][3][4]. The reduction in mobile phase viscosity at elevated temperatures, enhances diffusion rates and the mass transfer within the column and reduces column back-pressure so enabling faster eluent flows to be used without loss of efficiency.…”