Development of a nano-electrospray mass spectrometry source for nanoscale liquid chromatography and sheathless capillary electrophoresis

Abstract

A Fisons Quattro I electrospray ionization (ESI) source has been modified to produce stable electrospray ion currents at flow rates as low as 50 nL/min. The original counter electrode and skimmer cone lens of the Fisons ESI source have been replaced with a spherical cone lens. This improved source provides a greater range of x,y,z positioning of a stainless steel tip resulting in a stable ion signal for flow rates of 50 nL/min to 2 mL/min. A tapered stainless steel electrospray tip (50 mm i.d.) was evaluated for mass spectrometry using nano-liquid chromatography (50 mm i.d., flow rate = 120 nL/min) and sheathless capillary electrophoresis. The analysis of a nonionic surfactant, octylphenol ethoxylate, was accomplished with both nanoscale separation techniques. #

Robust and cost-effective capillary electrophoresis-mass spectrometry interfaces suitable for combination with on-line analyte preconcentration

“…The dilution effect is not necessary if other ways of applying electrical contact can be employed. For example, capillaries with a conductive-coated tip [10][11][12][13], a stainless steel tip [14], a microdialysis junction interface [15], direct electrode contact combinations [16][17][18][19], or even electrode-less systems [20] can be used. In these cases, the diluting effect of the make-up flow is avoided.…”

Metallized sheathless electrospray emitters for use in capillary electrophoresis orthogonal time‐of‐flight mass spectrometry

“…A similar approach has been taken for sheathless designs that introduce a gap between the emitter tip and the end of the CE column to generate an electrical contact. 7,8 This approach has been shown to be successful; however, the separation efficiency can be compromised by the introduction of a gap in the system. Sheathless chromium-gold coated capillaries on the other hand do not involve the addition of a sheath buffer and do not include a gap between the CE column and the emitter, so that separation efficiency and sensitivity are better optimized.…”

Interfaces for coupled liquid‐phase separation/mass spectrometry techniques. An update on recent developments

“…For instance, sheathless CE in a nanospray interface made up of a 50 µm i.d. ss tube ending in a tapered tip has been described 68. The tapered tip ss capillary end was connected to a 50 µm i.d.…”