smund Rinnan KULIFE Denmark aarlife ku dk NIR

Åsmund Rinnan, KU-LIFE, Denmark, aar@life. ku. dk NIR Pre-processing of NIR Åsmund Rinnan

Introduction NIR Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR Fructose Glucose 25 75 50 50 75 25

Introduction NIR Nonlinearity Fructose Glucose 25 75 50 50 75 25 A “fat” baseline Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR Baseline with a slope/ curve

Introduction Techniques – O-PLS – OSC – OS – SIS • Reference independent – MSC/ ISC – EMSC/ EISC – SNV – Detrend – Normalization – Savitzky-Golay – Norris-Williams – Finite difference Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR • Reference dependent

Introduction Techniques – MSC – EMSC – Detrend – SNV • Derivation – Finite difference – Savitzky-Golay Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR • Correction of light scatter

Effect of pre-processing Before Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR Specular effect

Effect of pre-processing After Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR

MSC Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR Reference Raw

MSC Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR Reference Raw

MSC Raw spectrum b = Slope a = Intercept Reference 1. P Geladi, D Mac. Dougal, H Martens (1985): Linearization and scatter correction for near-infrared reflectance spectra of meat , Applied Spectroscopy, 39, 491 -500 Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR

MSC Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR

Extended MSC Slope & Intercept Known spectra = Detrend Basic MSC 1. H. Martens, E. Stark (1991): Extended multiplicative signal correction and spectral interference subtraction: new preprocessing methods for near infrared spectroscopy, Journal of Pharmaceutical and Biomedicinal Analysis , 9, 625 -635 Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR Wavelength correction

Extended MSC The correction Step 1: Step 2: 1. H. Martens, E. Stark (1991): Extended multiplicative signal correction and spectral interference subtraction: new preprocessing methods for near infrared spectroscopy, Journal of Pharmaceutical and Biomedicinal Analysis , 9, 625 -635 Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR Calculated

Extended MSC Summary 1. Parameter setting X MSC 2. Parameter setting 3. Paraemter setting Detrend Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR X

SNV 1. R. J. Barnes, M. S. Dhanoa, S. J. Lister (1989): Standard Normal Variate Transformation and De-trending of Near-Infrared Diffuse Reflectance Spectra, Applied Spectroscopy, 43, 772 -777 Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR

SNV vs MSC Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR SNV MSC

SNV vs. MSC Classification of barley Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR

SNV vs. MSC • Reference needed • Outlier sensitive • Only similar spectra • No normalization Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR SNV • Normalization • No reference

Derivation Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR

Derivation Finite difference Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR

Savitzky-Golay vs. Finite difference 1 2 3 4 1 st SG Finite difference 0. 38 (5) 0. 40 (5) 0. 47 (6) 0. 34 (5) 0. 58 (4) 0. 73 0. 46 (3) 0. 46 (4) (3) 2 nd SG 0. 34 0. 51 0. 67 0. 46 (6) (4) (5) (3) 0. 72 0. 88 0. 91 0. 42 Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR Derivative Method

Derivation Savitzky-Golay 1. A Savitsky, M J E Golay (1964): Smoothing and differentiation of data by simplified least squares procedures , Analytical Chemistry, 36 (8), 1627 -1639 Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR

Derivation Savitzky-Golay 1. A Savitsky, M J E Golay (1964): Smoothing and differentiation of data by simplified least squares procedures , Analytical Chemistry, 36 (8), 1627 -1639 Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR Smoothing 197531

Derivation Savitzky-Golay 1. Polynomial 42531 A Savitsky, M J E Golay (1964): Smoothing and differentiation of data by simplified least squares procedures , Analytical Chemistry, 36 (8), 1627 -1639 Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR Smoothing 7

Derivation Savitzky-Golay 15 point smoothing 2 nd order derivative Åsmund Rinnan, KU-LIFE: aar@life. ku. dk NIR 7 point smoothing

Summary Pre-processing of NIR • Run the following for near to optimal results – Only 1 st order reference correction or SNV – 1 st order reference correction and 2 nd order wavelength correction – Only 2 nd order wavelength correction • Savitzky-Golay derivation with – 2 nd order polynomial smoothing – 7 points smoothing for the 1 st derivative – 9 points smoothing for the 2 nd derivative Åsmund Rinnan, KU-LIFE: aar@life. ku. dk • MSC with