NIR spectroscopy on moving solids using a scanning grating spectrometer - impact on multivariate process analysis

被引:35
作者
Andersson, M
Svensson, O
Folestad, S [1 ]
Josefson, M
Wahlund, KG
机构
[1] AstraZeneca R&D Molndal, AstraZeneca Ctr Excellence Proc Analyt Technol, S-43183 Molndal, Sweden
[2] Lund Univ, Ctr Chem & Chem Engn, Dept Tech Analyt Chem, S-22100 Lund, Sweden
关键词
near-infrared; scanning spectrometer; moving solids; multivariate analysis; fiber probe sampling; process analysis;
D O I
10.1016/j.chemolab.2003.10.007
中图分类号
TP [自动化技术、计算机技术];
学科分类号
0812 ;
摘要
The effect of sample movement on spectral response during fiber probe diffuse reflectance near-infrared spectrometry (NIR) sampling was characterized. This is of central importance in Process Analytical Chemistry (PAC) and Process Analytical Technology (PAT). The incitement to this study was the observation of spectral artifacts during measurements of powder samples in process streams when using a mechanically scanning spectrometer. Artifacts appeared as momentary changes in the spectral response during acquisition of a scan. These transitions emanate from continuous replacement of the sample subfraction seen by the probe and are typical for turbid media where sample properties may vary locally with respect to scattering and/or absorption. The impact on qualitative and quantitative analysis using chemometric methods such as principal component analysis (PCA) and partial least squares (PLS) regression was evaluated through experimental and theoretical simulations. It was generally found that spectra with the smallest residuals after projection onto the models came from non-moving samples or samples moving only slowly. It is shown that the magnitude of the spectral residuals is directly connected to the effective sample size, which relates both to sample speed as well as to the sample area presented to the probe. Implications for in-line/on-line process analysis of solids are discussed. (C) 2004 Elsevier B.V. All rights reserved.
引用
收藏
页码:1 / 11
页数:11
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