title: Desorption electrospray ionisation (DESI) for beginners--how to adjust settings for tissue imaging.
abstract: BACKGROUND
  Desorption electrospray ionisation (DESI) is the ambient technique used for surface imaging. Despite its simplicity, the proper use of this technique is not easy, and usually leads to discouragement, especially in the case of biological sample measurements. Here, we present some tips and tricks which may be helpful during a complex process of ion source optimisation to achieve the desired results.
  
  
  METHODS
  Rat liver tissue as an example of a biological sample and a surface covered with rhodamine-containing marker were measured using a DESI ion source (OMNIspray source, Prosolia, Indianapolis, IN, USA) connected to a AmaZon ETD ion trap mass spectrometer (Bruker Daltonics, Bremen, Germany).
  
  
  RESULTS
  The geometry of the ion source (nebulisation capillary angle, its distance to the surface, and to the MS inlet), and other settings like nebulising gas pressure, solvent flow and capillary voltage, were changed during the optimisation process. The results obtained for different parameters are presented.
  
  
  CONCLUSIONS
  Differences between the results and the method of optimisation for biological and non-biological samples were shown. The influence of different parameters on the quality of mass spectra was indicated. Optimal parameters for the tissue and non-biological sample analysis were suggested.
authors.affiliation: Department of Biochemistry and Neurobiology, Faculty of Materials Sciences and Ceramics, AGH University of Science and Technology, Mickiewicza 30 ave, 30-059, Krakow, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Bodzon-Kulakowska
authors.forename: Anna
authors.initials: A
authors.lastname: Drabik
authors.forename: Joanna
authors.initials: J
authors.lastname: Ner
authors.forename: Jolanta Helena
authors.initials: JH
authors.lastname: Kotlinska
authors.forename: Piotr
authors.initials: P
authors.lastname: Suder
mesh_terms: D000818:Animals; D006651:Histocytochemistry / Q000379:methods; D008099:Liver / Q000737:chemistry*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*