Abstract
It is generally accepted that the retention of solutes in non-polar eluents with silica as a stationary phase depneds on the silanol concentration. By thermall treatment silanols can be removed at temperatures above 200°C. It can be shown by Fourier transform (FT)-IR spectroscopy that the vicinal silanols are removed and that number of isolated silanols (sharp absorption at 3740 cm −) increases. The decrease of vicinal silanols can be detected chromatographically by a coresponding decrease in the retention of hydroxyl group-containing solutes. The retention of solutes with hydrogen-bonding acceptors is not affected by this removal of vicinal silanols. Their retention depends solely on the surface concentration of isolated silanols. At temperatures above 600°C the concentration of isolated silanols also decreases. Consequently, the retention of these solutes decreases only on silicas treated at higher temperature. Rehydration of silica surface is completely reversible, if the thermal treatment does not exceed 400°C. It appears that during chemical modification with chlorosilanes only the isolated hydroxy groups react.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
