One-pot synthesis of SiO2@SiO2 core-shell microspheres with controllable mesopore size as a new stationary phase for fast HPLC separation of alkyl benzenes and β-agonists
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Monodisperse SiO2@SiO2 core-shell silica microspheres (CSSM) with enlarged mesopores perpendicular to the particles surface were prepared using a dual-templating approach. With cetyltrimethyl ammonium bromide as the template and octyltrimethyl ammonium bromide as an auxiliary chemical, the pore size can be enlarged from 2.6 to 10.6 nm. The average shell thickness can be increased from 31 nm to 97 nm by adjusting the concentrations of the surfactants under continuous addition of tetraethyl orthosilicate. After coating twice, the resulting CSSM has a uniform mesoporous shell of about 198 nm thickness and a narrow pore size distribution. The CSSM were then modified with octadecyltrichlorosilane to give a material referred to as CS-C18. It was evaluated by separating the mixture of methylbenzene (toluene), ethylbenzene, n-propylbenzene, n-butylbenzene, n-amylbenzene and hexylbenzene. The baseline separation of the six alkyl benzenes is achieved within 2 min. Compared to a commercial column of type BEH-C18, CS-C18 shows a faster and better separation even at lower back pressure. It was also applied to the fast separation of benzo[a]pyrene, salbutamol, ractopamine and clenbuterolin residues in pork samples. The high column efficiency and better reproducibility suggest that the CSSM can be used as a matrix for fast separation and analysis of several kinds of small analytes.
KeywordsMonodisperse silica microsphere Mesoporous material Radially oriented channel Stationary phase Alkyl benzene homologues β-agonists HPLC
This work is supported by the National Nature Science Foundation of China (21874106, 21545007, 21605122), Shaanxi Provincial Science and Technology Coordinating Innovation Projects (2013SZS18-K01), Natural Science Foundation of Shaanxi Province (2018JZ2001, 2018JQ2011) the Foundation of Key Laboratory in Shaanxi Province (2010JS103, 11JS097, 15JS115, 16JS116) and Scientific Research Foundation of the Higher Education Institutions of Henan Province (18B150030).
Compliance with ethical standards
The author(s) declare that they have no competing interests.
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