The geometric characterization of porous adsorbents used as stationary phases in high performance liquid chromatography is a key aspect for the understanding and the description of retention mechanisms. Herein, we present a study aimed at describing the geometric characteristics of alkyl-perfluorinated silica stationary phases by employing chromatographic and non-chromatographic techniques. This study shows that, under typical chromatographic conditions, the perfluorohexylpropyl straight chains grafted to the silica surface assume a compact arrangement. As perfluorinated stationary phases are highly hydrophobic, their wetting behavior in water was investigated. To this end, a novel approach based on tracer pulse chromatography with pure water as the mobile phase and deuterium oxide as the labeled marker was employed. Experimentally it was found that, unless a high back-pressure is applied, water is expelled by the pores of the adsorbent. On the other hand, wetting can be significantly improved if 5-10% (v/v) of organic modifier is added to the mobile phase. The practical consequences of limited wettability are discussed, in particular with reference to fluorous-SPE (F-SPE) applications. (C) 2013 Elsevier B.V. All rights reserved.
Geometric characterization of straight-chain perfluorohexylpropyl adsorbents for high performance liquid chromatography / Alberto, Cavazzini; Luisa, Pasti; Roberto, Greco; Valentina, Costa; Damiano, Solera; Francesco, Dondi; Nicola, Marchetti; Lagana', Aldo; Gasparrini, Francesco. - In: JOURNAL OF CHROMATOGRAPHY A. - ISSN 0021-9673. - STAMPA. - 1286:(2013), pp. 47-54. [10.1016/j.chroma.2013.02.050]
Geometric characterization of straight-chain perfluorohexylpropyl adsorbents for high performance liquid chromatography
LAGANA', Aldo;GASPARRINI, Francesco
2013
Abstract
The geometric characterization of porous adsorbents used as stationary phases in high performance liquid chromatography is a key aspect for the understanding and the description of retention mechanisms. Herein, we present a study aimed at describing the geometric characteristics of alkyl-perfluorinated silica stationary phases by employing chromatographic and non-chromatographic techniques. This study shows that, under typical chromatographic conditions, the perfluorohexylpropyl straight chains grafted to the silica surface assume a compact arrangement. As perfluorinated stationary phases are highly hydrophobic, their wetting behavior in water was investigated. To this end, a novel approach based on tracer pulse chromatography with pure water as the mobile phase and deuterium oxide as the labeled marker was employed. Experimentally it was found that, unless a high back-pressure is applied, water is expelled by the pores of the adsorbent. On the other hand, wetting can be significantly improved if 5-10% (v/v) of organic modifier is added to the mobile phase. The practical consequences of limited wettability are discussed, in particular with reference to fluorous-SPE (F-SPE) applications. (C) 2013 Elsevier B.V. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.