Nanoliter-scale etched capillary electrospray interface of mass spectrometry

A nanoliter-scale electrospray interface for mass spectrometry was developed by modifying the commercial sheathflow interface for capillary electrophoresis coupling with mass spectrometry(CE-MS). The interface was fabricated by using HF etching on a 50 mu m i. d. fused-silica capillary. The outer wall of the. interface was shown a porous structure, and its thickness was as thin as about 10 mu m. A protein sample, cytochrome c., was analyzed by using the etched interface at. the volumetric flow rate as low. as 20 nL/min., The influence of contacting electrolyte between the etched capillary and the stainless steel sheath tube on ESI was investigated and explained. The comparative study of electrospray performance of the commercial micro stainless steel interface and the etched one was carried out by using protein as sample. The higher response signal was achieved by using the modified interface in the flow rate range of 50-500 nL/min. The sensitivity of detection was increased 3.6 times at the flow rate of 200 nL/min compared with the commercial micro interface.