Column preparation micro HPLC

Mlcrodevlces. The sol-gel technique allows the reproducible preparation of capillary electrochromatography (CEC) microcolumns that could be used for high performance separation in microfabricated devices (microchips). Eluid hydrolyzed silica sols can be injected into the microchip-channels. Condensation occurs inside the device micro-HPLC column made of silica gel (Constantin, 2001). 

Gas chromatography (gc) is inferior to hplc in separating abiUty. With gc, it is better to use capillary columns and the appHcation is then limited to analysis (67). Resolution by thin layer chromatography or dc is similar to Ic, and chiral stationary phases developed for Ic can be used. However, tic has not been studied as extensively as Ic and gc. Chiral plates for analysis and preparation of micro quantities have been developed (68). 

The most thorough investigation in this area was that of Harrison and Royle43 on astatination of rabbit immunoglobulin (IgG) which could be used in animal experiments. PAtBA was produced with > 90% radiochemical yield, and a reproducible overall yield of > 30% for labelled protein was obtained with negligible deastatination of the latter in vivo. These favourable results could be achieved most probably due to the fact that the PAtBA was prepared without an iodine carrier and that the micro amounts of the product were purified from the macro amounts of contaminates by HPLC. To bind PAtBA to the protein, acylation with mixed anhydride was used. Preparation of the mixed anhydride 7 (equation 5) could be carried out in about 20 minutes at ca 0 °C. For astatination rabbit IgG protein is dissolved in borate buffer (pH = 9.3) and then added to 7 (see equation 6) the procedure takes about 1 hour at ca 15 °C. The astatinated protein is separated from non-conjugated materials by gel filtration and eluted from the column by phosphate-buffered saline. 

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