Chen Yi-Chieh, Foo David, Dehanov Nicolau, Thennadil Suresh N
Department of Chemical and Process Engineering, University of Strathclyde, 75 Montrose Street, Glasgow, G1 1XJ, UK.
School of Engineering and Information Technology, Charles Darwin University, Darwin, NT, 0909, Australia.
Anal Bioanal Chem. 2017 Dec;409(30):6975-6988. doi: 10.1007/s00216-017-0672-4. Epub 2017 Oct 12.
Successful implementation of process analytical technology (PAT) hinges on the ability to make continuous or frequent measurements in-line or at-line of critical product attributes such as composition and particle size, the latter being an important parameter for particulate processes such as suspensions and emulsions. A novel probe-based spatially and angularly-resolved diffuse reflectance measurement (SAR-DRM) system is proposed. This instrument, along with appropriate calibration models, is designed for online monitoring of concentration of chemical species and particle size of the particulate species in process systems involving colloidal suspensions. This measurement system was investigated using polystyrene suspensions of various particle radius and concentration to evaluate its performance in terms of the information obtained from the novel configuration which allows the measurement of a combination of incident light at different angles and collection fibres at different distances from the source fibres. Different strategies of processing and combining the SAR-DRM measurements were considered in terms of the impact on partial least squares (PLS) model performance. The results were compared with those obtained using a bench-top instrument which was used as the reference (off-line) instrument for comparison purposes. The SAR-DRM system showed similar performance to the bench top reference instrument for estimation of particle radius, and outperforms the reference instrument in estimating particle concentration. The investigation shows that the improvement in PLS regression model performance using the SAR-DRM system is related to the extra information captured by the SAR-DRM configuration. The differences in SAR-DRM spectra collected by the different collection fibres from different angular source fibres are the dominant reason for the significant improvement in the model performance. The promising results from this study suggest the potential of the SAR-DRM system as an online monitoring tool for processes involving suspensions. Graphical abstract A probe designed to acquire diffuse reflectance measurements at different source-detector distances for three incidence angles 0°, 30° and 45° was used to estimate particle size and concentration of polystyrene beads in aqueous suspension using partial least squares calibration models.
过程分析技术（PAT）的成功实施取决于能否对关键产品属性（如成分和粒径）进行在线或近线的连续或频繁测量，粒径对于悬浮液和乳液等颗粒过程而言是一个重要参数。本文提出了一种基于新型探头的空间和角度分辨漫反射测量（SAR-DRM）系统。该仪器与适当的校准模型一起，旨在对涉及胶体悬浮液的过程系统中的化学物质浓度和颗粒物质的粒径进行在线监测。使用具有不同颗粒半径和浓度的聚苯乙烯悬浮液对该测量系统进行了研究，以根据从新型配置获得的信息评估其性能，该配置允许在不同角度测量入射光并在距源光纤不同距离处收集光纤。考虑了不同的处理和组合SAR-DRM测量的策略对偏最小二乘（PLS）模型性能的影响。将结果与使用台式仪器获得的结果进行比较，该台式仪器用作参考（离线）仪器以作比较。对于颗粒半径的估计，SAR-DRM系统表现出与台式参考仪器相似的性能，并且在估计颗粒浓度方面优于参考仪器。研究表明，使用SAR-DRM系统时PLS回归模型性能的提高与SAR-DRM配置捕获的额外信息有关。不同收集光纤从不同角度源光纤收集的SAR-DRM光谱差异是模型性能显著提高的主要原因。这项研究的良好结果表明了SAR-DRM系统作为涉及悬浮液过程的在线监测工具的潜力。图形摘要 使用一个设计用于在三个入射角0°、30°和45°下在不同源 - 探测器距离处获取漫反射测量的探头，通过偏最小二乘校准模型来估计水悬浮液中聚苯乙烯珠的粒径和浓度。
