Quantitative Spectroscopy

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Edvard Lauritsen
5 år siden
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1 Salón Jade 2, Instructor Wes Walker Quantitative Spectroscopy 1. Introduction 2. Algorithms 3. Software 1

Quantitative Spectroscopy Quantitative Spectroscopy 1 -

3 Chapter 1 Outline Instruments Chemometric literature Justification for using calibrated spectroscopic methods Calibration design Putting the calibration into service 3

4 Instruments DISCUSSION ON INSTRUMENTS 4

5 Literature C. Eckhart and G. Young, "The approximation of one matrix by another of lower rank, Psychometrika, 1(3), (1936). R. D. B. Fraser and E. Suzuki, "Resolution of overlapping absorption bands by least squares procedures," Anal. Chem., 38(12), (1966). P. T. Funke, E. R. Malinowski, D. E. Martire, and L. Z. Pollara, "Application of factor analysis to the prediction of activity coefficients of nonelectrolytes," Separation Science, 1(6), (1966). R. E. Bargmann, "Exploratory techniques involving artificial variables," in "Multivariate Analysis-II", Proc. Second International Symposium on Multivariate Analysis held at Wright State Univ., Dayton, OH, (June 1968). P. R. Krishnaiah, Ed., Academic Press, NY (1969). B. R. Kowalski and C. F. Bender, "The application of pattern recognition to screening prospective anticancer drugs. Adenocarcinoma 755 biological activity test," JACS, 96(3), 916 (1974). A. Hoskuldsson, PLS Regression Methods, Journal of Chemometrics 2 (1988). 5

6 Literature My favorites R. Kramer, Chemometric Techniques for Quantitative Analysis, Marcel Dekker, ISBN Chemometrics: A Practical Guide, K.R. Beebe, R.J. Pell, M.B. Seasholtz, Wiley-Interscience, ISBN Customer favorites R.G. Brereton, Chemometrics: Data Analysis for the Laboratory and Chemical Plant, John Wiley and Sons, Hoboken, NJ, (ISBN ). E.R. Malinowski, Factor Analysis in Chemistry, 3rd ed, Wiley-Interscience, New York, (ISBN ). H. Mark, Principles and Practice of Spectroscopic Calibration, John Wiley & Sons, New York, H. Martens and M. Martens, Multivariate Analysis of Quality: An Introduction, John Wiley & Sons, New York, H. Martens and T. Naes, Multivariate Calibration, John Wiley & Sons, New York, E. Morgan, Chemometrics: Experimental Design, John Wiley & Sons, New York,

7 Literature ReactIR user papers: Monitoring and Feedback Control of Supersaturation Using ATR-FTIR to produce an Active Pharmaceutical Ingredient of a Desired Crystal Size, Vincenzo Liotta, Vijay Sabesan, Organic Process Research and Development, 2004, 8, Influence of Solvent and Operating Conditions on the Crystallization of Racemic Mandelic Acid, Crystal Growth and Design, 2004, Vol. 4, No. 2, Veronica M. Profir, Ake C. Rasmuson. Determination of the End point of a Chemical Synthesis Process Using On- Line Measured Mid-Infrared Spectra, De Braekeleer, K., de Juan, F., Cuesta Sánchez, F., Hailey, P. A., Sharp, D. C. A., Dunn, P., Massart, D. L., Applied Spectroscopy, 54(4), 2000, pp Monitoring ph Swing Crystallization of Nicotinic Acid by the Use of Attenuated Total Reflection Fourier Transform Infrared Spectrometry. Fang Wang, Kris A. Berglund, Industrial and Engineering Chemistry Research, 2000, 39,

8 Justification for using quantitative spectroscopic models To put a calibrated spectroscopic method into service one must: 1. Design the calibration 2. Record calibration standard spectra 3. Validate (test) the calibration 4. Maintain the calibration Wouldn t it be easier to make a trend from a peak or use ConcIRT? Yes, but a trend based on one or two variables (for instance peak height to single point baseline) often does not give the accuracy required to satisfy an objective: DISCUSSION ON OBJECTIVES 8

9 Calibration design 1. Write down the objective. Be thorough and specific We want to determine the end point of a reaction so that we can replace the titration method which takes a lot of time and sample preparation. The endpoint is reached when the concentration of one of the staring materials benzyl ester CH 3 COOCH 2 C 6 H 5 reaches a concentration of 4% by weight with an accuracy of 0.5% by weight. 2. Decide how the calibration (training) standards and initial validation (evaluation) standards will be acquired. Each standard consists of a spectral data component (the spectrum) and a numerical data component DISCUSSION ON CALIBRATION STANDARDS 9

10 Calibration design 2. Decide how the calibration (training) standards and initial validation (evaluation) standards will be acquired. Each standard consists of a spectral data component (the spectrum) and a numerical data component It was decided that eight spectrum / titration number data points would be collected for each of three reaction runs for a total of 24 standard spectra. Twenty of these are to be used for calibration standards and four will be used for validation standards. DISCUSSION ON VALIDATION STANDARDS 10

11 Calibration design standard number / purpose reaction conc. wt/wt% from titration 1-Calibration Calibration Calibration Validation Calibration Calibration Calibration Calibration Calibration Calibration Calibration Calibration Calibration Validation Calibration Calibration Calibration Calibration Calibration Validation Calibration Validation Calibration Calibration

12 Putting the calibration into service 3. The calibration is validated and put into service. How does the calibration hold up to validation in the coming days and weeks. DISCUSSION ON PUTTING THE CALIBRATION INTO SERVICE 12

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