The Raftery Group is led by Professor M. Daniel Raftery of Purdue University's Department of Chemistry. Their research focuses on the development and application of advanced methods in metabolomics and bioanalytical NMR spectroscopy. Professor Raftery's laboratory utilizes the latest technological advancements in nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS) methods for analyzing biological samples from a variety of pathological and other biological conditions. The complex datasets obtained are analyzed using multivariate statistical analyses. In addition, the lab is involved in the development of new chemical and technical methods for the enhancement of sensitivity and selectivity for biomarker detection. See Metabolomics-Based Methods for Biomarker Discovery of Disease for a description of the biomarker discovery workflow.

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Instruments
When used in GCxGC mode, the LECO Pegasus 4D GCxGC-TOF can separate and detect hundreds-to-thousands of compounds in a single sample. Separations, which previously resulted in dozens or hundreds of peaks, now yield thousands of individual components from complex mixtures. The powerful, easy-to-use ChromaTOF software simplifies component identification by employing integrate NIST database searches. Other unique processing capabilities (such as sample comparisons) allow for automated mining of complex GCxGC data sets to extract previously unidentifiable similarities and differences. Ionization is performed using electron impact (EI). The upper mass limit for this instrument is 1,000 daltons. Different derivitization schemes are routinely employed to assist in sample volatility. See sample preparation protocol and instrument setup for detailed descriptions of the Raftery Group sample processing methodologies.

The Bruker Avance 500MHz Spectrometer with cryoprobe is operated by the Purdue Interdepartmental NMR Facility. It is equipped with a 5mm cryoprobe with 1H sensitivity > 3000:1 and is used heavily for routine NMR in the Raftery Lab's metabolomics projects, including the Cancer Care Engineering project.

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Datasets

The LECO Pegasus 4D GCxGC-TOF generates ".PEG" files during instrument sample processing. For GCxGC mass spectrometry analysis, LECO software is used to convert the LECO-generated ".PEG" files to netCDF and CSV files. The netCDF files can then be used as input to the GCxGC MS Alignment and Classification Tool developed by the statistical modeling group and the GCxGC MS OMIC Explorer Tool developed by the Purdue University Regional Visualization and Analytics Center. Both GCxGC-MS tools are available as cceHUB resources. See the netCDF Format for an in-depth discussion of the format and content of the LECO GCxGC MS netCDF files.

FID data is acquired from the Bruker Avance 500MHz Spectrometer instrument analysis, and Fourier transformations are computed on the FID data to get the spectrum. This is a very typical NMR data transformation and can be done with any Fourier transformation. The FID data is immediately transferred into the spectrum data when each experiment is done, and only the spectrum is kept and analyzed. See this description of the Fourier Transformation of the NMR FID format data. NMR data from muliple samples is stored in one Excel spreadsheet, as shown in this example XLS file, where every row represents ppm(variable) and each column represents a sample, in this case, Sample 1 (S1) to Sample n (Sn).