A new method for preparation of an etched porous joint for capillary electrophoresis and its pore-size evaluation

In this work, an improved approach was developed for the construction of a hydrofluoric acid etched capillary porous joint, and the pore size of the porous joint was investigated. Several etching factors such as reagents concentration and etching temperature were optimized. Results showed that moderate temperature with low hydrofluoric acid concentration was helpful for proportional etching. Low-range protein molecular weight marker labeled with acridinium ester was used as pore-size reference for pore-size evaluation of the joint. A homemade CE with chemiluminescence detection system was used for the analysis of the acridinium ester labeled protein molecular weight marker, and the results showed that only the small molecular peptides can pass through the etched porous joint and the big size proteins cannot. The penetration of protein whose molecular mass was larger than 6500 Da was a signal of over-etching.