Mesoporous polybutadiene-modified zirconia for high-temperature packed capillary liquid chromatography: column preparation and temperature programming stability.
In the present study, three different methods for packing of 3 microm PBD-ZrO2 particles in 0.5 mm i.d. glass-lined stainless steel columns have been examined. The two first methods were based on a traditional downstream high-pressure technique using tetrachloromethane (Method I) or aqueous Triton X-100 (Method II) as slurry solvents, while Method III was an upstream high-pressure flocculating method with stirring, using isopropanol both as the slurry and packing solvent. Method I was found to be superior in terms of efficiency, producing 0.5 mm i.d. x 10 cm columns with almost 90,000 plates m(-1) for toluene (R.S.D. = 8.7%, n = 3), using a slurry concentration of 600 mg ml(-1), ACN-water (50:50 (v/v)) as the packing solvent and a packing pressure of 650 bars. For Method I, the slurry concentration, column i.d., column length and initial packing pressure were found to have a significant effect on column efficiency. Finally, the long-term temperature stability of the prepared columns was investigated. In isothermal mode, using ACN-20 mM phosphate buffer, pH 7 (50:50 (v/v)) as the mobile phase, the columns were found to be stable for at least 3,000 void volumes at 100 degrees C. At this temperature, the solute efficiencies changed about 5-18% and the retention factors changed about 6-8%. In temperature programming mode (not exceeding 100 degrees C), on the other hand, a rapid decrease in both column efficiency and retention factors was observed. However, when the columns were packed as initially described, ramped up and down from 50 to 100 degrees C for 48 h and refilled, fairly stable columns with acceptable efficiencies were obtained. Although not fully regaining their initial efficiency after refilling, the solute efficiencies changed about 19-28% (32-37%) and the retention factors changed about 4-5% (13-17%) after running 3,000 (25,000) void volumes or 500 (3,900) temperature programs.
Department of Chemistry, University of Oslo, PO Box 1033 Blindern, N-0315 Oslo, Norway. than@kjemi.uio.no
Thomas
T
Andersen
Quynh-Nhu T
QN
Nguyen
Roger
R
Trones
Tyge
T
Greibrokk
D002070:Butadienes / Q000737:chemistry*; D002853:Chromatography, Liquid / Q000295:instrumentation* / Q000379:methods; D020724:Elastomers; D006358:Hot Temperature; D008855:Microscopy, Electron, Scanning; D011108:Polymers / Q000737:chemistry*; D013054:Spectrophotometry, Atomic; D013696:Temperature; D015040:Zirconium / Q000737:chemistry*
D002070:Butadienes; D020724:Elastomers; D011108:Polymers; C028834:polybutadiene; D015040:Zirconium; C028541:zirconium oxide