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Continuous‐flow liquid microjunction surface sampling probe connected on‐line with high‐performance liquid chromatography/mass spectrometry for spatially resolved analysis of small molecules and proteins
Author(s) -
Van Berkel Gary J.,
Kertesz Vilmos
Publication year - 2013
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.6580
Subject(s) - chemistry , mass spectrometry , chromatography , analytical chemistry (journal) , flow (mathematics) , molecule , sampling (signal processing) , organic chemistry , mechanics , physics , filter (signal processing) , computer science , computer vision
RATIONALE A continuous‐flow liquid microjunction surface sampling probe extracts soluble material from surfaces for direct ionization and detection by mass spectrometry. Demonstrated here is the on‐line coupling of such a probe with high‐performance liquid chromatography/mass spectrometry (HPLC/MS) enabling extraction, separation and detection of small molecules and proteins from surfaces in a spatially resolved (~0.5 mm diameter spots) manner. METHODS A continuous‐flow liquid microjunction surface sampling probe was connected to a six‐port, two‐position valve for extract collection and injection to an HPLC column. A QTRAP® 5500 hybrid triple quadrupole linear ion trap equipped with a Turbo V™ ion source operated in positive electrospray ionization (ESI) mode was used for all experiments. The system operation was tested with the extraction, separation and detection of propranolol and associated metabolites from drug dosed tissues, caffeine from a coffee bean, cocaine from paper currency, and proteins from dried sheep blood spots on paper. RESULTS Confirmed in the tissue were the parent drug and two different hydroxypropranolol glucuronides. The mass spectrometric response for these compounds from different locations in the liver showed an increase with increasing extraction time (5, 20 and 40 s). For on‐line separation and detection/identification of extracted proteins from dried sheep blood spots, two major protein peaks dominated the chromatogram and could be correlated with the expected masses for the hemoglobin α and β chains. CONCLUSIONS Spatially resolved sampling, separation, and detection of small molecules and proteins from surfaces can be accomplished using a continuous‐flow liquid microjunction surface sampling probe coupled on‐line with HPLC/MS detection. Published in 2013. This article is a U.S. Government work and is in the public domain in the USA.