Light Scattering and Light Absorbance Separated by Extended Multiplicative Signal Correction. Application to Near-Infrared Transmission Analysis of Powder Mixtures

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• 作者：Harald Martens ; Jesper Pram Nielsen ; and S//pubs.acs.org/images/gifchars/oslash.gif" border="0">ren Balling Engelsen
• 刊名：Analytical Chemistry
• 出版年：2003
• 出版时间：February 1, 2003
• 年：2003
• 卷：75
• 期：3
• 页码：394 - 404
• 全文大小：361K
• 年卷期：v.75,no.3(February 1, 2003)
• ISSN：1520-6882

文摘

The extended multiplicative signal correction (EMSC)preprocessing method allows a separation of physicallight-scattering effects from chemical (vibrational) lightabsorbance effects in spectra from, for example, powdersor turbid solutions. It is here applied to diffuse nearinfrared transmission (NIT) spectra of mixtures of wheatgluten (protein) and starch (carbohydrate) powders, linearized by conventional log(1/T). Without any correctionfor uncontrolled light scattering variation between thepowder samples, these absorbance spectra could givereasonable predictions of the analyte (gluten), but onlywhen using multivariate calibration with a much morecomplex model than expected. Standard MSC preprocessing did not work for these data at all; it removed too muchanalyte information. However, the EMSC preprocessingyielded powder spectra that obeyed Beer's Law more orless as if they had been obtained from transparent liquidsolutions, apparently by isolating the chemical lightabsorption from additive, multiplicative, and wavelength-dependent effects of uncontrolled light-scattering variations. The model-based EMSC and its converse, theextended inverted signal correction (EISC), gave rathercomplete descriptions of the diffuse absorbance spectraand virtually indistinguishable performance in the calibration set and the test set of samples.