An enhanced droplet-based liquid microjunction surface sampling system coupled with HPLC-ESI-MS/MS for spatially resolved analysis
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Droplet-based liquid microjunction surface sampling coupled with high-performance liquid chromatography (HPLC)-electrospray ionization (ESI)-tandem mass spectrometry (MS/MS) for spatially resolved analysis provides the possibility of effective analysis of complex matrix samples and can provide a greater degree of chemical information from a single spot sample than is typically possible with a direct analysis of an extract. Described here is the setup and enhanced capabilities of a discrete droplet liquid microjunction surface sampling system employing a commercially available CTC PAL autosampler. The system enhancements include incorporation of a laser distance sensor enabling unattended analysis of samples and sample locations of dramatically disparate height as well as reliably dispensing just 0.5 μL of extraction solvent to make the liquid junction to the surface, wherein the extraction spot size was confined to an area about 0.7 mm in diameter; software modifications improving the spatial resolution of sampling spot selection from 1.0 to 0.1 mm; use of an open bed tray system to accommodate samples as large as whole-body rat thin tissue sections; and custom sample/solvent holders that shorten sampling time to approximately 1 min per sample. The merit of these new features was demonstrated by spatially resolved sampling, HPLC separation, and mass spectral detection of pharmaceuticals and metabolites from whole-body rat thin tissue sections and razor blade (“crude”) cut mouse tissue.
KeywordsLiquid microjunction Droplet-based liquid extraction Autosampler Spatial distribution Laser distance sensor
The API 4000 instrument used in this work was provided on loan, and advancement of this surface sampling technology was supported by funding provided through a Cooperative Research and Development Agreement (CRADA NFE-10-02966) with AB Sciex. Drs. Jimmy Flarakos, Paul Moench, Adam Bentley, and Alexandre Catoire (Novartis Pharmaceuticals Corporation, East Hanover, NJ) are thanked for providing the whole-body rat thin tissue sections through a Work for Others (WFO) agreement with Novartis Institutes for Biomedical Research. AstraZeneca Pharmaceuticals (Waltham, MA, USA) is thanked for providing the AZ-3-dosed mouse tissues through a WFO agreement. T.M.W. acknowledges an ORNL appointment through the ORISE HERE program that was supported through the WFO agreement with Novartis Institutes for Biomedical Research. The authors would like to thank Lonnie J. Love from the Manufacturing Demonstration Facility of the Oak Ridge National Laboratory for his valuable help in 3D printing of the custom trays.
- 13.Kertesz V, Paranthaman N, Moench P, Catoire A, Flarakos J, Van Berkel GJ (2014) Bioanal (In press)Google Scholar