Abstract

Attenuated total reflection (ATR) – Fourier transform infrared (FTIR) spectroscopy with the pretreatment of converting the absorption spectrum into angle spectrum (CASAS) and partial least squares (PLS) was employed to rapidly and simultaneously determine the ingredients of cellulose slurries and solutions during lyocell production. ATR was employed to rapidly and conveniently collect the spectra of the swollen slurries and viscous solutions during production. CASAS was used to eliminate the influence on modeling by the optical path differences due to uneven ingredient distributions in the samples. The PLS models for the cellulose, water, and N-methylmorpholine N-oxide (NMMO) concentrations of the cellulose slurry/solution were constructed using the raw spectra, pretreated spectra by CASAS, and common pretreatment methods, respectively. The results show that CASAS eliminates interferences due to the differences in optical path and improves the performance of PLS model for each analyte. The standard errors of prediction (SEP) of models using CASAS for cellulose, NMMO, and water concentration of cellulose slurry were 0.368, 0.196 and 0.171, while the values for the cellulose solution were 0.442, 0.353, and 0.066, respectively. The standard errors of prediction (SEPs) of CASAS models are significantly lower than the reproducibility requirement of the reference method, 0.5. The reported approach using ATR-FTIR spectroscopy combined with CASAS and PLS is rapid and accurate for determining the ingredients of the cellulose slurries and solutions and offers potential for identifying similar samples.

摘要

衰减全反射（ATR）-傅里叶变换红外（FTIR）光谱与吸收光谱转换为角光谱（CASAS）和偏最小二乘法（PLS）的预处理被用来快速同时测定纤维素浆料和溶液的成分。莱赛尔生产。ATR 用于在生产过程中快速方便地收集溶胀浆液和粘性溶液的光谱。CASAS用于消除由于样品中成分分布不均匀导致的光程差异对建模的影响。分别使用原始光谱、CASAS 预处理光谱和常用预处理方法构建了纤维素浆/溶液的纤维素、水和 N-甲基吗啉 N-氧化物 (NMMO) 浓度的 PLS 模型。结果表明，CASAS消除了由于光路差异造成的干扰，提高了PLS模型对每种分析物的性能。使用 CASAS 模型对纤维素、NMMO 和纤维素浆液浓度的预测标准误差 (SEP) 分别为 0.368、0.196 和 0.171，而纤维素溶液的值分别为 0.442、0.353 和 0.066。CASAS 模型的预测标准误差 (SEP) 显着低于参考方法的重现性要求，即 0.5。报告的使用 ATR-FTIR 光谱结合 CASAS 和 PLS 的方法可以快速准确地确定纤维素浆液和溶液的成分，并为识别类似样品提供了潜力。