Desorption electrospray ionization (DESI) is a technique used for direct sampling of a sample or an analyte deposited on a surface under ambient conditions [1]. In DESI, ionized droplets of a spray are directed towards the sample causing desorption of ions due to exchange of charge and momentum. The resulting ions are carried into an ion trap mass spectrometer and analyzed. DESI was originally demonstrated by Takats et al. [1]. They described the new method and applied the same to analyze various compounds present on a variety of surfaces. Followed by this, several researchers [1–5] have investigated on DESI for a wide range of applications including analysis of pharmaceuticals, explosives detection, natural products discovery and in vivo clinical analysis. Recently, Kauppila et al [5] have introduced porous silicon (pSi) and ultra-thin layer chromatography (UTLC) plates for DESI-MS. Similar or improved sensitivities were obtained with pSi and UTLC surfaces as compared to PMMA and PTFE surfaces. This work presents use of a nanoporous alumina surface [6] for DESI – MS. The DESI – MS performance of nanoporous alumina surface is compared with that of PMMA, which is a popular surface in previous DESI-MS experiments. Optimized operating conditions were determined for the surfaces using BSA tryptic digest as the sample. The results show that the nanoporous alumina surface offers significantly higher ion intensity as compared to the other surfaces.

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