Tube structure with sol-gel zirconia coating

Abstract

The subject invention concerns zirconia-based hybrid organic-inorganic sol-gel coating for optional use as a stationary phase in capillary microextraction (CME), gas chromatographic (GC), high performance liquid chromatography (HPLC), capillary electrophoresis (CE), capillary electrochromatography (CEC) and related analytical techniques. Sol-gel chemistry is employed to chemically bind a hydroxy-terminated silicone polymer (polydimethyldiphenylsiloxane, PDMDPS) to a sol-gel zirconia network. In one embodiment, a fused silica capillary is filled with a properly designed sol solution to allow for the sol-gel reactions to take place within the capillary. In the course of this process, a layer of the evolving hybrid organic-inorganic sol-gel polymer becomes chemically bonded to the silanol groups on the inner capillary walls. The unbonded part of the sol solution is expelled from the capillary under helium pressure, leaving behind a chemically bonded sol-gel zirconia —PDMDPS coating on the inner walls of the capillary. Polycyclic aromatic hydrocarbons, ketones, and aldehydes are efficiently extracted and preconcentrated from dilute aqueous samples followed by GC separation of the extracted analytes.

1 . A sol solution coated column comprising: 
 a) a vessel having a bore, defining an inner surface of the vessel; and    b) a deactivated, sol-gel zirconia-polymer stationary phase coating chemically bonded to the inner surface of the vessel; wherein said chemical bond comprises a —Si—O—Zr— bond.    
   
   
       2 . The column of  claim 1 , wherein the zirconia is provided by zirconium butoxide.  
   
   
       3 . The column of  claim 1 , wherein the polymer is dimethyldiphenylsiloxane.  
   
   
       4 . The column of  claim 1 , wherein the vessel is a fused silica capillary.  
   
   
       5 . The column of  claim 1 , wherein the coating comprises a zirconia-polydimethyldiphenylsiloxane coating, wherein said zirconia is chemically bonded to said polydimethyldiphenylsiloxane coating via a —Zr—O—Si— bond.  
   
   
       6 . A sol-gel coated column prepared according to the steps of: 
 a) providing a fused-silica capillary comprising a vessel having a bore, defining an inner surface of the capillary;    b) filling the fused-silica capillary with a sol solution comprising: 
 i) a sol-gel precursor comprising a zirconia solution;  
 ii) a stationary phase coating;  
 iii) a chelating reagent; and  
 iv) a deactivating reagent;  
 dissolved in a solvent for a residence time sufficient for the sol solution to evolve into a sol-gel stationary phase and to chemically bond to the inner surface of the capillary, wherein said chemical bond comprises a —Si—O—Zr— bond;  
   c) expelling any residual sol solution; and    d) conditioning the sol-gel coated capillary;    whereby a deactivated, sol-gel zirconia-polymer stationary phase coated column is made.    
   
   
       7 . The sol-gel coated column according to  claim 6 , wherein the sol-gel precursor is a zirconium (IV) alkoxide.  
   
   
       8 . The sol-gel coated column according to  claim 6 , wherein the sol-gel precursor is zirconium (IV) butoxide.  
   
   
       9 . The sol-gel coated column according to  claim 6 , wherein the stationary phase coating is a silanol-terminated poly(dimethyldiphenylsiloxane) copolymer, wherein said zirconia is chemically bonded to said polydimethyldiphenylsiloxane coating via a —Zr—O—Si— bond.  
   
   
       10 . The sol-gel coated column according to  claim 6 , wherein the chelating agent is selected from the group consisting of acetic acid, triethanolamine, 1,5-diaminopentane, acetylacetonate, acetoacetate, valeric acid, and a combination of any of the foregoing.  
   
   
       11 . The sol-gel coated column according to  claim 6 , wherein the deactivating reagent is selected from the group consisting of poly(methylhydrosilozane), hexamethyldisilozane, and a combination of both.  
   
   
       12 . The sol-gel coated column according to  claim 6 , wherein the solvent is methylene chloride.  
   
   
       13 . The sol-gel coated column according to  claim 6 , wherein the conditioning step comprises a first heating step comprising heating the capillary from 40° C. to 150° C. at 1° C. per minute and maintaining the temperature at 150° C. for 300 minutes, a second heating step comprising heating the capillary from 150° C. to 320° C. at 1° C. per minute and maintaining the temperature at 320° C. for 120 minutes; and a third heating step comprising heating the capillary from 40° C. to 320° C. at 4° C. per minute; wherein the first heating step and the second heating step take place sequentially; and wherein a cleaning step comprising rinsing the capillary with a solvent precedes the third heating step.  
   
   
       14 . The sol-gel coated column according to  claim 6 , wherein the residence time of step b) comprises 10 to 15 minutes.  
   
   
       15 . The sol-gel coated column according to  claim 6 , wherein the residence time of step b) comprises 30 minutes.