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Salón Jade 2, Instructor Wes Walker

Quantitative Spectroscopy1. Introduction2. Algorithms3. Software

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Quantitative Spectroscopy

Quantitative Spectroscopy1 - Introduction

Copyright 2006 Mettler-Toledo AutoChem, Inc.

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Chapter 1 Outline

InstrumentsChemometric literatureJustification for using calibrated spectroscopic methodsCalibration designPutting the calibration into service

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Instruments

DISCUSSION ON INSTRUMENTS

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Literature

C. Eckhart and G. Young, "The approximation of one matrix by another of lower rank,“ Psychometrika, 1(3), 211-218 (1936). R. D. B. Fraser and E. Suzuki, "Resolution of overlapping absorption bands by least squares procedures," Anal. Chem., 38(12), 1770-1773 (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), 661-676 (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, 17-22 (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).

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Literature

My favoritesR. Kramer, Chemometric Techniques for Quantitative Analysis, Marcel Dekker, ISBN 0-8247-0198-4. Chemometrics: A Practical Guide, K.R. Beebe, R.J. Pell, M.B. Seasholtz, Wiley-Interscience, ISBN 0-471-12451-6

Customer favoritesR.G. Brereton, Chemometrics: Data Analysis for the Laboratory and Chemical Plant, John Wiley and Sons, Hoboken, NJ, 2003. (ISBN 0-471-48978-6).

E.R. Malinowski, Factor Analysis in Chemistry, 3rd ed, Wiley-Interscience, New York, 2002. (ISBN 0-471-13479-1).

H. Mark, Principles and Practice of Spectroscopic Calibration, John Wiley & Sons, New York, 1991.

H. Martens and M. Martens, Multivariate Analysis of Quality: An Introduction, John Wiley & Sons, New York, 2001.

H. Martens and T. Naes, Multivariate Calibration, John Wiley & Sons, New York, 1989.

E. Morgan, Chemometrics: Experimental Design, John Wiley & Sons, New York, 1991.

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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, 488-494.“Influence of Solvent and Operating Conditions on the Crystallization of Racemic Mandelic Acid”, Crystal Growth and Design, 2004, Vol. 4, No. 2, 315-323. 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 601-607 “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, 39,2101-2104

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Justification for using quantitative spectroscopic models

To put a calibrated spectroscopic method into service one must:

1. Design the calibration2. Record calibration standard spectra3. Validate (test) the calibration4. 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

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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 CH3COOCH2C6H5reaches 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

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Calibration design

2. Decide how the calibration (training) standards and initial validation (evaluation) standards will be acquired. Each standard consistsof a spectral data component (the spectrum) and a numericaldata component…

It was decided that eight spectrum / titration number data points would becollected 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 willbe used for validation standards.

DISCUSSION ON VALIDATION STANDARDS

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Calibration design

standard number / purpose reaction conc. wt/wt% from titration

1-Calibration 1 5.62-Calibration 1 5.43-Calibration 1 4.94-Validation 1 4.45-Calibration 1 3.86-Calibration 1 3.17-Calibration 1 2.68-Calibration 1 2.5

9-Calibration 2 5.5 10-Calibration 2 5.011-Calibration 2 4.012-Calibration 2 3.613-Calibration 2 3.414-Validation 2 2.915-Calibration 2 2.716-Calibration 2 2.4

17-Calibration 3 5.818-Calibration 3 5.119-Calibration 3 4.220-Validation 3 3.721-Calibration 3 3.622-Validation 3 3.123-Calibration 3 2.824-Calibration 3 2.6

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Putting the calibration into service

3. The calibration is validated and put into service.

How does the calibration hold up to validation in the comingdays and weeks.

DISCUSSION ON PUTTING THE CALIBRATION INTO SERVICE