Responding to the need for acid/base stable (pH 1 to 14) phases for biochromatography, we developed highly stable HPLC stationary phases based on monodisperse 3 micron spheres of zirconia. It is now clear that zirconia offers an additional major advantage over conventional materials: it can be used at temperatures of 200 C and higher. We will use this stability to explore vapor phase deposition of polymers from chemically reactive monomers (such as 1,3-butadiene) to prepare stationary phases with both improved mass transfer characteristics and surface shielding of the deleterious Zr(IV) Lewis acid sites which can impede the chromatography of Lewis base analytes, especially peptides and proteins. We will also investigate the use of ethylene diamino tetramethylene phosphonic acid derivatives to make stable monomeric stationary phases for RPLC, NPLC and chiral chromatography. In a departure from all previous efforts, which have focused on the synthesis, characterization and use of zirconia phases, we now propose, given the extraordinary stability of zirconia relative to other chromatographic supports, to explore temperature as a principal operating variable in HPLC. In particular, we will develop both ultra-fast and ultra-selective analytical HPLC at super ambient temperatures. The more than 20-fold decrease in viscosity due to changing the eluent temperature from 25 to 200 C, and the proportional increase in molecular diffusivity, should allow much faster (10-20 fold) HPLC to become routine. It will certainly decrease pressure drops at normal flow rates, allowing the use of much longer (20x) columns and increasing total plate counts. In conjunction with gradient elution, this will provide a greatly needed increase in peak capacity of HPLC with conventional equipment. Additionally, a significant body of recent work has focused on the use of temperature as a method of fine """"""""tuning"""""""" chromatographic selectivity and optimizing resolution. The greatly extended range in temperature of ZrO2 (to 200 C) vs. SiO2 based supports should considerably enhance the achievable changes in selectivity. The extraordinary temperature stability of both polybutadiene and carbon coated zirconia, and their distinctly different chromatographic selectivities, opens the door to extending the exciting concept of thermally tuned tandem column chromatography to RPLC, bringing about major improvements in our ability to manipulate chromatographic selectivity and optimize separations in HPLC.
Showing the most recent 10 out of 51 publications
