Easy ambient sonic-spray ionization mass spectrometry for tissue imaging

Abstract

Two spray-based ambient ionization methods, desorption electrospray ionization (DESI) and easy ambient sonic-spray ionization (EASI), have been successfully used to obtain tissue images of rat brain samples, for the first time, using both sources under their optimized conditions. Good ion images have been obtained by both techniques in MS and no significant difference was observed in the spray spot size. A comparative study between DESI and EASI on sensibility was also done and EASI was found to have similar or slightly higher sensitivity than DESI depending on the lipids interrogated (fatty acids, triacylglycerols and phospholipids). Thus, EASI can therefore be applied for tissue imaging particularly when the application of high voltage is impractical or undesirable.