Chip-based nanoelectrospray ionization

Hop, C.E., Chen, Y., and Yu, L.J., Uniformity of ionization response of structurally diverse analytes using a chip-based nanoelectrospray ionization source, Rapid Commun. Mass Spectrom., 19(21), 3139, 2005. 

Amon, S., TreUe, M.B., lensen, O.N., J0rgensen, T.l. (2012) Spatially resolved protein hydrogen exchange measured by subzero-cooled chip-based nanoelectrospray ionization tandem mass spectrometry. Anal Chem, 84 (10), 4467-A473. 

Kertesz, V. and Van Berkel, G.J. 2010. Fully automated liquid extraction-based surface sampling and ionization using a chip-based robotic nanoelectrospray platform, J. Mass Spectrom., 45 252-260. 

Another instrumental development is based on the fact that the generation of smaller droplets is more favorable in terms of droplet evaporation during ESI, of sensitivity and the abihty to preserve non-covalent molecular associates. Thus, nanoelectrospray ionization (nESI) has been developed [68], where the analyte is sprayed from a gold-coated fused-silica capillary with a tip diameter of 1-5 pm rather than from capillaries with a 100-150-pm tips that are used in conventional (pneumatically assisted) ESI. In nESI, flow-rates as low as 20 nl/min can be nebulized. Thus, gentler operating conditions (temperature, gas flows, needle voltage) can be achieved. In order to more readily implement nESI in LC-MS operation, integrated chip-based nano-LC-nESI devices have also been developed [69]. 

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