Journal of Chromatography A, 1419 (2015) 45–57 Contents lists available at ScienceDirect Journal of Chromatography A j o ur na l ho me page: www.elsevier.com/locate/chroma Thermal pretreatments of superficially porous silica particles for high-performance liquid chromatography: Surface control, structural characterization and chromatographic evaluation  Mélanie Mignot a , Muriel Sebban b , Alain Tchapla c , Olivier Mercier d , Pascal Cardinael a , Valérie Peulon-Agasse a,∗ a Normandie Univ, EA3233, Sciences et Méthodes Séparatives, FR3038, IRCOF, 1 rue Tesniere, 76821 Mont Saint-Aignan Cedex, France b Normandie Univ, UMR 6014, Chimie Organique, Bioorganique: Réactivité et Analyse, FR3038, IRCOF, 1 rue Tesniere, 76821 Mont Saint-Aignan Cedex, France c Lip(Sys) 2 – LETIAM (FKA EA4041 Groupe de Chimie Analytique de Paris-Sud), Univ Paris-Sud, Université Paris-Saclay, IUT d’Orsay, Plateau de Moulon, F-91400 Orsay, France d Interchim R&D, 211 bis avenue JF Kennedy, BP 1140, 03100 Montluc ¸ on, France a r t i c l e i n f o Article history: Received 27 July 2015 Received in revised form 18 September 2015 Accepted 22 September 2015 Available online 26 September 2015 Keywords: High-performance-liquid-chromatography Superficially porous silica particles Octadecylsilane stationary phases Silica thermal treatment Principal component analysis Microwave irradiation a b s t r a c t This study reports the impact of thermal pretreatment between 400 and 1100 ◦ C on superficially porous silica particles (e.g. core-shell, fused-core; here abbreviated as SPP silica). The different thermally pre- treated SPP silica (400 ◦ C, 900 ◦ C and 1100 ◦ C) were chemically bonded with an octadecyl chain under microwave irradiation. The bare SPP silica, thermally untreated and pretreated, as well as the chemically bonded phases (CBPs) were fully characterized by elemental analysis, diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), and solid state cross polarization magic angle spinning (CP-MAS) 29 Si NMR. The chromatographic properties of the overall set of C 18 -thermally pretreated SPP silica stationary phases were determined using the Tanaka test. Complementary, the simplified Veuthey test was used to deeply study the silanol activity, considering a set of 7 basic solutes with various physicochemical properties. Both tests were also performed on different commercial SPP silica columns and different types of bond- ing chemistry (C18, Phenyl-hexyl, RP-amide, C30, aQ). Multivariate data analyses (hierarchical cluster analysis and principal component analysis) were carried out to define groups of stationary phases with similar chromatographic properties and situate them in relation to those commercially available. These different C 18 -thermally pretreated SPP silicas represented a wide range of stationary phases as they were spread out along the score plot. Moreover, this study highlighted that the thermal pretreatment improved the chemical stability of the SPP silica compare to untreated SPP silica and untreated porous silica. Con- sequently, higher thermal pretreatment can be applied (up to 900 ◦ C) before functionalization without destruction of the silica matrix. Indeed, a significantly lower dissolution of the thermally pretreated SPP silica under aggressive conditions could allow the use of the corresponding functionalized stationary phases at high temperature (60 ◦ C) with good lifetime of the columns. © 2015 Elsevier B.V. All rights reserved. 1. Introduction Silica is largely used as a support of the stationary phase in High-Performance Liquid Chromatography (HPLC) because of its numerous advantages, including its large specific surface area and its mechanical stability. The particles can be manufactured as small  Selected paper from 42nd International Symposium on High Performance Liquid Phase Separations and Related Techniques, 21–25 June 2015, Geneva, Switzerland. ∗ Corresponding author. E-mail address: valerie.agasse@univ-rouen.fr (V. Peulon-Agasse). spheres with a narrow size distribution and a controlled pore size, which makes a good starting material for preparing efficient HPLC stationary phases. To increase the chromatographic efficiency and improve the productivity, several methods are currently used such as Ultra- High-Performance Liquid Chromatography (UHPLC) with fully porous sub-2 m particles, which may or may not be coupled with High-Temperature Liquid Chromatography (HTLC), or the use of monolithic stationary phases. Among these methods, the use of superficially porous silica particles (SPP silica) is another alterna- tive requiring neither specific apparatus nor complicated transfer http://dx.doi.org/10.1016/j.chroma.2015.09.072 0021-9673/© 2015 Elsevier B.V. All rights reserved.