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Assessment of Multivariate Chemometric Methods Combined with Comprehensive Two-dimensional Gas Chromatography Towards Determination of Aromatic Compounds in Complex Samples

Eftekhari, Ali | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48798 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Parastar Shahri, Hadi
  7. Abstract:
  8. In recent years, comprehensive two-dimensional gas chromatography (GC×GC) have emerged as a powerful technique suitable for the separation of complex mixtures because of their higher resolution and higher peak capacity. The invention of GC×GC is a milestone development in chromatographic history. However, one of the main challenges in chromatography and especially in GC×GC is related to the difficulty on the analysis and interpretation of the enormous amount of data obtained in these cases. In this context, resolution, identification and quantification of target compounds in the presence of interferences are issues which have a great importance and not totally solved yet. The present contribution is devoted to develop multivariate analytical figures of merit (AFOMs) as a new metric for evaluation of quantitative measurements using GC×GC. In this regard, new definition of sensitivity (SEN) is extended to GC×GC data and then, other multivariate AFOMs including analytical SEN (γ), selectivity (SEL) and limit of detection (LOD) are developed. Also, two frequently used second-order calibration (SOC) algorithms of multivariate curve resolution-alternating least squares (MCR-ALS) as representative of multi-set methods and parallel factor analysis (PARAFAC) as representative of multi-way methods are discussed to exploit pure component profiles to calculate multivariate AFOMs. Different GC×GC-MS data sets with different number of components along with various levels of artifacts are simulated and analyzed. Noise, elution time shifts in both chromatographic dimensions, peak overlap and interferences are considered as the main artifacts in this work. Additionally, a new strategy is developed to estimate the noise level using variance-covariance matrix of residuals which is very important to calculate multivariate AFOMs. Finally, determination of polycyclic aromatic hydrocarbons (PAHs) in aromatic fraction of heavy fuel oil (HFO) analyzed by GC×GC-MS is considered as real case to confirm applicability of the proposed metric in real samples. It should be pointed out that the proposed strategy in this work can be used for other types of comprehensive two-dimensional chromatographic techniques like comprehensive two dimensional liquid chromatography (LC×LC)
  9. Keywords:
  10. Chemometrics Method ; Multivariate Curve Resolution-Alternative Least Square (MCR-ALS) ; Merit Matherials Figure ; Aromatic Compounds ; Comprehensive Two Dimensional Gas Chromatography ; Parallel Factors Analysis

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