Gas Aggregated Ag Nanoparticles As The Inorganic Matrix For Laser Desorption/Ionization Mass Spectrometry

We report here on a nanoparticle-assisted laser desorption/ionization time-of-flight mass spectrometry (NP-LDI-TOF MS) for the detection of small molecules. This technique is based on the overcoating of a dried analyte by an array of silver nanoparticles produced by gas aggregation source. This allows for the spatially homogeneous distribution of nanoparticles over the analyte that may fully substitute a conventional organic matrix routinely used for the matrix-assisted laser desorption/ionization mass spectrometry and thus limit the possible interference of matrix with the low-mass molecules. Furthermore, it is shown that the intensity of the detected signal strongly correlates with the number of deposited Ag nanoparticles. At its optimum, that was found to correspond to the nanoparticle surface density of 3x10(3) NPs.mu m(-2), the detection limit was 3x10(-8) g.L-1 for riboflavin. Such a high detection limit, together with good reproducibility, excellent signal stability, and imaging capability, makes this technique a valuable alternative to other laser desorption/ionization-based detection methods.