Effects of Sample Preparations in Ultraviolet Matrix-Asisted Lase Desorption/Ionization Time of Flight Mass Spectrometry

Y. SATO; E. M. RUSTOY; H. NONAMI; R. ERRA-BALSELLS; A. BALDESSARI; C. A. STORTZ; A. S. CEREZO; M. C. MATULEWICZ

Tsukuba, Japón

Congreso; The 56th Annual Conference on Mass Spectrometry; 2008

Japan Society of Mass Spectrometry

Effects of Sample Preparations in Ultraviolet Matrix-Assisted Laser Desorption/Ionization Time-of-flight Mass Spectrometry (1Ehime University · 2 Universidad de Buenos Aires, Argentina) Yasuto Sato1, Eduardo M. Rustoy 2, Hiroshi Nonami1, Rosa Erra-Balsells2, Alicia Baldessari2 , Carlos A. Stortz2, Alberto S. Cerezo2 and María C. Matulewicz2 Short Abstract: Sample preparation in ultraviolet matrix-assisted desorption/ionization (UV-MALDI) analysis is critical because it affects not only the successes of analysis but also the qualities of mass spectra. However the relations between analyte, the sample preparations and the properties of analyte ions were not predicted perfectly. For observation of the relation in UV-MALDI-TOFMS, model analytes with various sample preparation (different matrices, sample preparation methods (sandwich method and mixture method)) were measured.  Not only qualities of ions originated from analyte (ion species, signal distributions of copolymers, etc.) but also the experimental parameters (Laser threshold for detecting analyte, etc.) were also studied. Keywords: MALDI, nor-Harmane, saccharides, sample preparation, polymers For UV-MALDI analysis, sample preparations like choices of matrix and choices of sample preparation methods are critical because it affects not only the successes of analysis but also types of ion species originated from analyte and signal-to-noise ratio. UV-MALDI-TOFMS is used for analyses of polysaccharide, proteins, synthetic polymers, etc. however the relations between analyte, the sample preparations and the properties of analyte ions were not predicted perfectly, since the details of mechanisms of the desorption/ionization processes have not been understood.  Thus, application of UV-MALDI-TOFMS is limited to compounds, which derivatives have already studied closely.             For observation of the relations in UV-MALDI-TOFMS, three types of analyte (N-acyl monosaccharides, copolymers catalyzed by lipase and dendron) as models with various sample preparation on the positive/negative modes were attempted. 2,5-dihydroxybenzoic acid (DHB), nor-Harmane (norHo), 2-(4-hydroxyphenylazo)-benzoic acid (HABA) and 5-chloro-2-mercaptobenothiazole (CMBT) were used as matrices.  Two type of sample preparation methods were attempted; mixture method and sandwich method. Different matrix solutions were dropped on the same holes in some cases of sandwich methods. Not only qualities of ions originated from analyte (ion species, signal distributions of copolymers, PSD fragmentation, etc.) but also the experimental parameters (Laser threshold for detecting analyte, distributions of sweet spots, reproducibility of signals on the same spots, etc.) were also studied. Morphologies of samples were also checked and attempted to find out relation between sample preparations and morphologies.