Posters

      Computer‐Assisted Structure Identification: Predictive Models and Automation

      Monge, A.; Knorr, A.; Stueber, M.; Arndt, D.; Stratmann, A.; Martin, E.; Peitsch, M. C.; Ivanov, N. V.; Pospisil, P.
      Conference date
      Jun 27, 2011
      Conference name
      Metabolomics 2011
      Link to more information
      Link to more information
      Topic
      Summary

      The CASI (Computer-Assisted Structure Identification) approach is used at Philip Morris International R&D to identify small molecules in complex matrices analyzed with GCxGC-TOF-MS. In the CASI approach, structure candidates and associated match factors for a mass spectrum are obtained using NIST MS search. In order to refine the results of NIST MS search, we developed quantitative structure−property relationship models to predict values of the two retention times of a GCxGC-TOF-MS instrument. A Kovats indices model was built for the first dimension and a model developed for the second dimension using relative retention times that are specific for the GCxGC-TOF-MS instrument: non-polar (1st dimension) x polar (2nd dimension). The models can be adapted for different column combinations. Results obtained by k-nearest neighbors, multiple linear regression, and support vector machines for each type of model were compared. For each algorithm, the best sets of descriptors were chosen using genetic algorithms. The process is fully automated using java and several other standard tools, such as NIST MS search for searches in a mass spectral database, dragon for computing molecular descriptors, RapidMiner to apply predictive retention models, pipeline pilot to normalize chemical structures, and ACD/labs PhysChem batch to compute boiling points. CASI web interface proposes a list of the best matched structure candidates allowing users to easily check and correct structure assignments. CASI also enables the user to easily add new instruments, analytical columns, and retention models to the platform.

      PMIScience.com is operated by Philip Morris International for the purpose of publishing and disseminating scientific information about Philip Morris International’s efforts in support of its smoke-free product portfolio. This site is a global site for use by scientists, the public health and regulatory communities, and other stakeholders with an interest in tobacco policy. The purpose of this site is not advertising or marketing, nor is it directed at any specific market. It is not intended for use by consumers. New tobacco products sold in the United States are subject to FDA regulation; therefore the content of this site is not intended to make, and nor should it be construed as making, any product related claims in the United States without proper FDA authorization. ​
      ​
      Reduced Risk Products ("RRPs”) is the term we use to refer to products that present, are likely to present, or have the potential to present less risk of harm to smokers who switch to these products versus continuing smoking. PMI has a range of RRPs in various stages of development, scientific assessment and commercialization. All of our RRPs are smoke-free products that deliver nicotine with far lower quantities of harmful and potentially harmful constituents than found in cigarette smoke.