NOVELTY - A plate comprises an electroconductive substrate (1) at least partially covered with sintered nanoparticles (2), deposited as an array of individual spots, for use as a sorbing phase for a sample, and for supporting ionization of sorbed sample molecules covered by or present in an overlayer or matrix. The overlayer or matrix comprises a light absorber and/or a charged carrier acid. USE - Plate is used for matrix-assisted laser desorption ionization mass spectrometry analysis of molecules or reaction products (oxidized or reduced) of molecules, such as oligomers, oligosaccharides and biomolecules e.g. peptides, oligonucleotides (all claimed), proteins, and DNA. Can also be used for tagging reactions, disulfide bridge reductions, and ion source decay reactions. ADVANTAGE - The plate provides a very efficient tool to analyze biomolecules by mass spectrometry and to study the products of photo-induced electron transfer reactions. DETAILED DESCRIPTION - A plate comprises an electroconductive substrate at least partially covered with sintered nanoparticles, deposited as an array of individual spots, for use as a sorbing phase for a sample, and for supporting ionization of sorbed sample molecules covered by or present in an overlayer or matrix. The overlayer or matrix comprises a light absorber and/or a charged carrier acid. The nanoparticles are made of titania, alumina, zinc oxide, silica, ferrous oxide, zirconia, and/or niobium oxide. Or, the nanoparticles are quantum dots, such as cadmium sulfide, cadmium selenide, zinc oxide, or materials which can be photosensitized. The sorbing nanoparticles are derivatized by hydrophobic molecules to specifically bind other hydrophobic molecules, such as peptides. The electroconductive substrate comprises stainless steel, aluminum, nickel, zinc, copper, silicon, tin-indium oxide on glass, or conductive/semi-conductive polymer. INDEPENDENT CLAIMS are included for the following: (1) preparation method of plate; and (2) usage method of plate. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the plate. Electroconductive substrate (1) Sintered nanoparticles (2) Laser (3) Material including molecules from sample (4)