On-column conductive coating for thermolabile columns used in capillary zone electrophoresis sheathless electrospray ionisation mass spectrometry

A simple and very mild approach for the application of a conductive layer for sheathless electrospray has been developed. A modified 'fairy dust' method is employed in which 2 microm gold particles are applied by a thin layer of silicone on shaped tips. This novel approach comprises fabrications at room temperature, under atmospheric pressure, and involves no etching, extensive cleaning or otherwise harsh conditions. With this approach, sheathless electrospray emitters have been fabricated from fused silica capillaries with chemically pre-modified inner walls and from heat-sensitive polypropylene hollow fibres. Long term stability for more than two weeks of continuous spraying has been achieved. Capillary zone electrophoresis/time-of-flight mass spectrometry demonstrates attomole sensitivity and no detectable band broadening. A comparison with a chromium-gold coated emitter in terms of chemical noise is made with continuous infusion experiments, showing no significant increase in background from the polymer involved.