Electrospray ionization sample consumption

Nanoelectrospray ionization (nanoESI), also known as nanospray, nanoflow electrospray, and micro-electrospray, is a low flow/high sensitivity approach to ESI. NanoESI15 is a slight variation on ESI such that the spray needle has been made very small and is positioned close to the entrance of the vacuum of the mass spectrometer and the mass analyzer (Figure 6). This greatly reduces required sample amounts allowing nanoliter flow rates and femto-mole sample consumption. The end result is increased efficiency since the flow rates for... 

Most recently (Schneider 2006) an experimental source was used to conduct studies under conditions of total solvent consumption , with pneumatically assisted nebu-lization to stabilize the ESI process, a heated laminar flow chamber to enhance desolvation and ion production, and various atmosphere-to-vacuum aperture diameters to maximize ion transfer. The motivation for these experiments was to investigate the proposal that the reason for the much lower ionization sampling efficiencies at higher flow rates ( o,L.min and above) is that the electrosprayed droplets are much larger in view of the much larger ESI needle tip diameters required to maintain flow rates in this regime, and thus are much less efficiently evaporated down to the Rayleigh and/or ion evaporation limits than the droplets formed from the 1 (tm diameter tips nsed in nano-ESI (Juraschek 1999 Schmidt 2003). 

Miniaturized LC/MS formats based on micromachined chip-based electrospray emitters and ionization sources on silicon (Schultz et al., 2000 Licklider et al., 2000 Ramsey and Ramsey 1997 Xue et al., 1997) and plastic (Vrouwe et al., 2000 Yuan and Shiea, 2001, Tang et al., 2001) microchips is a proactive approach for scale-down platforms. Various micromachining processes are used to fabricate these devices. These microanalytical technologies would create integrated sample preparation and LC/MS applications. The potential benefits of such a system include reduced consumption of sample/reagents, low cost, and disposability. 

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