The sol-gel process has been utilized for the fabrication of silica nanoparticles to be used in HPLC columns. This process may be a reasonable means to create small (1-1.5 μm) spherical silica particles reliably for ultra-high pressure liquid chromatography. For the best use of this technique the various conditions of synthesis must be optimized. Currently the process has been optimized in terms of the amount of reagents (tetraethoxysilane or TEOS and octyltriethoxysilane or C8 TEOS) but there has been significant variation in size from batch to batch. To examine possible sources of this variation several batches of particles were synthesized varying, stir bar speed, stir bar shape and amount of ammonia gas added. All syntheses with reaction volume less than 200ml yielded unusable particles. The syntheses with 80, 105, 130 and 150 ml of added ammonia resulted in particles with an average sizes from 1.1-1.7μm in diameter. Though there is still variation within the volumes there appears to be some correlation between ammonia added and particles size. The biggest predictor of size appears to be the rate of temperature increase. In the experiments with a constant temperature bath the rate of temperature increase was rapid and the particle sizes were smaller.
A method to pack the resulting hybrid particles was also developed for testing under UHPLC conditions; this included the examination of several packing pressures combination, slurry solvents and slurry concentration. In this document, the particulars of the packing method and chromatographic testing of the columns will be presented. The resulting columns were tested comparing the performance of column with particles bearing a C8 moiety with allyl functionalized particles before and after modification.
The complexity of packing particles was examined using particle with differing surface chemistries. The three stationary phases tested included octyl, allyl and hydride containing particles.
Also the C8 packed column is compared to a commercially available Kovasil™ column packed with nonporous C8 material. The overall column performance, retention permeability, porosity and many other column properties were all explored. This testing showed that Kovasil column have higher efficiency while the column packed in house had better results for nonspecific interactions, retention and mass load ability
|Advisor:||Colon, Luis A.|
|Commitee:||Aga, Diana S., Watson, Dave F., Wood, Troy D.|
|School:||State University of New York at Buffalo|
|School Location:||United States -- New York|
|Source:||DAI-B 74/06(E), Dissertation Abstracts International|
|Subjects:||Chemistry, Analytical chemistry|
|Keywords:||Hplc, Hybrid particles, Organosilica materials, Silica based particulates, Sol-gel, Uhplc|
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