Browsing by Subject "MALDI-TOF"
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Item Open Access A Green Chemistry Analysis of Metal Complexes by MALDI-TOF(2017-05-05) Jernigan, ChristopherMatrix-Assisted Laser Desorption/Ionization (MALDI) is a type of ionization that is commonly used for the analysis of high molecular weight biological compounds, but has also been used for metal complex analysis. By combining the work presented in previously published literature on low molecular weight techniques and metal complexes, an analysis of different methods was evaluated. Spectra of transition metals chelated by three different ligands using different chelating atoms were acquired. To analyze the complexes, four different matrices were used with three different plating methods. In the evaluation of the different methods, the amount of solvent used was recorded and compared to a similar ionization technique, electrospray ionization (ESI). The experiment demonstrated that MALDI had the capability to ionize more complexes while using less solvent than ESI.Item Open Access Characterising phase variations in MALDI-TOF data and correcting them by peak alignment.(Cancer Inform, 2005) Lin, Simon M; Haney, Richard P; Campa, Michael J; Fitzgerald, Michael C; Patz, Edward FThe use of MALDI-TOF mass spectrometry as a means of analyzing the proteome has been evaluated extensively in recent years. One of the limitations of this technique that has impeded the development of robust data analysis algorithms is the variability in the location of protein ion signals along the x-axis. We studied technical variations of MALDI-TOF measurements in the context of proteomics profiling. By acquiring a benchmark data set with five replicates, we estimated 76% to 85% of the total variance is due to phase variation. We devised a lobster plot, so named because of the resemblance to a lobster claw, to help detect the phase variation in replicates. We also investigated a peak alignment algorithm to remove the phase variation. This operation is analogous to the normalization step in microarray data analysis. Only after this critical step can features of biological interest be clearly revealed. With the help of principal component analysis, we demonstrated that after peak alignment, the differences among replicates are reduced. We compared this approach to peak alignment with a model-based calibration approach in which there was known information about peaks in common among all spectra. Finally, we examined the potential value at each point in an analysis pipeline of having a set of methods available that includes parametric, semiparametric and nonparametric methods; among such methods are those that benefit from the use of prior information.