Non-tapered PTFE capillary as robust and stable nanoelectrospray emitter for electrospray ionization mass spectrometry.

Abstract

The successful implementation of electrospray ionization mass spectrometry (ESI-MS) largely relies on the physical and chemical properties of electrospray emitters. Current ESI emitters based on pulled glass or fused-silica capillaries suffer from complicated fabrication procedures and short lifetime because of clogging and breakage problems. ESI emitters with high robustness, easy operation, and low cost are in great demand. We proposed to directly use non-pulled and non-tapered polytetrafluoroethylene (PTFE) capillaries as nanoelectrospray emitters. We evaluated and studied the performance of PTFE emitters under different flow rates and ESI voltages. Their applications in direct infusion and liquid chromatography (LC)-MS analysis were achieved. High stable electrospray (relative standard deviation of total ion current intensity <5%) can be obtained at flow rates from 100nL/min to 1500nL/min and at ESI voltages from 1.8kV to 2.9kV using non-tapered PTFE emitters. Different types of samples including small-molecule drugs, peptides, and proteins can be detected with high sensitivity. LC-MS analysis of two model peptides was successfully demonstrated. We have demonstrated that a non-tapered PTFE capillary can be a promising ESI emitter for both direct infusion and LC-MS analysis. We envision it could find broad applications in high-throughput MS analysis fields, such as drug screening and proteomics, where robust and reproducible operations are essentially required. Copyright © 2016 John Wiley & Sons, Ltd.