Liquid microjunction

Van Berkel GJ, Kertesz V, Koeplinger KA, Vavrek M, Kong A-NT. Liquid microjunction surface sampling probe electrospray mass spectrometry for detection of drugs and metabolites in thin tissue sections. J Mass Spectrom 2008 43 500-508. 

ESI Liquid microjunction surface sampling probe. Van Berkel and... 

Van Berkel, G.J., Kertesz, V. (2009) Electrochemically Initiated Tagging of Thiols Using an Electrospray Ionization Based Liquid Microjunction Surface Sampling Probe Two-electrode Cell. Rapid Commun. Mass Spectrom. 23 1380-1386. 

Kertesz, V., Van Berkel, G.J. (2010) Liquid Microjunction Surface Sampling Coupled with High-Pressure Liquid Chromatography-Electrospray Ionization-Mass Spectrometry for Analysis of Drugs and Metabolites in Whole-body Thin Tissue Sections. Anal. Chem. 82 5917-5921. 

Walworth, M.J., Stankovich, J.J., Van Berkel, G.J., Schulz, M., Minarik, S., Nichols, J, Reich, E. (2011) Hydrophobic treatment enabling analysis of wettable surfaces using a liquid microjunction surface sampling probe/electrospray ionization-mass spectrometry system. Analytical Chemistry, 83, 591-597. 

In 1998, Anderson and Busch presented an offline TLC-MS probe composed of an array of microcapillaries [9]. This device lacked the general sensitivity of Luftmann s device because it only sampled the uppermost layer of the TLC plate. Nevertheless, it also planted the idea of MS imaging of sample spots from the developed TLC plates by an elution-based approach. Van Berkel further developed this concept in 2002 [10]. A liquid microjunction surface sampling probe enabled stepwise as well as continuous sampling mode of operation, which theoretically could be used for imaging analyses of whole TLC plates. The spatial resolution was a function of scan speed and the nature of the eluting solvent. This device underwent many improvements in the following years however, it has been never commercialized. 

FIGURE 8.2 Schematic representation of a liquid-microjunction surface sampling probe. 

Ambient MS is another advance in the field. It allows the analysis of samples with little or no sample preparation. Following the introduction of desorption electrospray ionization (DESI) [108,109], direct analysis in real time (DART) [110], and desorption atmospheric pressure chemical ionization (DAPCI) [111, 112], a number of ambient ionization methods have been introduced. They include electrospray-assisted laser desorption/ionization (ELDI) [113], matrix-assisted laser desorption electrospray ionization (MALDESI) [114], atmospheric solids analysis probe (ASAP) [115], jet desorption ionization (JeDI) [116], desorption sonic spray ionization (DeSSI) [117], field-induced droplet ionization (FIDI) [118], desorption atmospheric pressure photoionization (DAPPI) [119], plasma-assisted desorption ionization (PADI) [120], dielectric barrier discharge ionization (DBDI) [121], and the liquid microjunction surface sampling probe method (LMJ-SSP) [122], etc. All these techniques have shown that ambient MS can be used as a rapid tool to provide efficient desorption and ionization and hence to allow mass spectrometric characterization of target compounds. 

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