Spectroscopy process

In plastics processing temperature is a decisive process control parameter. Time dependent temperatures can be measured with high accuracy and short response time (msec) using IR sensors that detect the heat radiation from molten plastic [34]. 

Sensor systems (e-noses) for at-Une measurement, coated with various gas sensitive materials which react differently with the volatiles to be analysed, detect differences rather than absolute values. It is possible to verily quickly deviation from the standard. Process titrators are used today in many industrial fields of process control. The range of applications is extraordinary large [27,35]. 

In a broad sense, spectroscopic methods applied in process analytics comprise widely used techniques like UVA IS, mid-IR, NIR, NMR and XRF, and less frequently used ones, such as Raman spectroscopy, fluorescence, chemiluminescence, acoustic emission and dielectric specfloscopy. Upcoming in-process analysis techniques are 2D-fluorescence, and laser absorption specfloscopy (LAS) with tuneable lasers and ppm level sensitivity. The availability of mini-spectrometers (e.g. UVA IS/NIR) is not highly relevant in plant environments where safety is of primary concern. 

Temperature Relatively insensitive Needs to be controlled Small T changes affect band shapes/positions in NIR 

Flow-rate Requires control, or use of stopped-flow Insensitive  

---

Safety mnst be the first consideration of any process analytical installation. Electrical and weather enclosures and safe instrnment-process interfaces are expected for any process spectroscopy installation. The presence of a powerfnl laser, however, is nniqne to process Raman instruments and mnst be addressed due to its potential to injnre someone. Eye and skin injnries are the most common resnlts of improper laser exposure. Fortunately, being safe also is easy. Becanse so many people have seen pictnres of large industrial cutting lasers in operation, this is often what operations personnel erroneonsly first envision when a laser installation is discnssed. However, modem instmments nse small footprint, comparatively low power lasers, safely isolated in a variety of enclosures and armed with various interlocks to prevent accidental exposnre to the beam. 

However, process spectroscopy is, almost by definition, done to measure and control an industrial process. Most of the work is driven by business needs, such as improving profits or product quality. In competitive business environments, firms preserve every advantage possible by protecting valuable measurement systems... 

Figure 12.27 (A) Scatter plot of the Hotelling P and Q residual statistics associated with the samples in the process spectroscopy calibration data set, obtained from a PCA model built on the data after obvious outliers were removed. The dashed lines represent the 95% confidence limit of the respective statistic. (B) The spectra used to generate the plot in (A), denoting one of the outlier samples.

Figure 12.29 Time-series plot of the y-residuals obtained from a PLS model developed using the process spectroscopy calibration data set (solid line), after removal of sample and variable outliers as discussed earlier. The measured y-values (dashed line) are also provided for reference.

Figure 12.32 Sample selection scatter plots of the first two PCs obtained from a process spectroscopy dataset containing 200 samples, indicating the subset of 10 samples selected using the leverage-based method (A), the D-optimal method (B), and the ffCA-based method (C).

Process spectroscopy is, almost by definition, done to measure and control an industrial process. Almost all of the work is driven by business needs, such as improving profits or product quality. In competitive business environments, firms preserve every advantage possible by protecting valuable measurement systems as trade secrets. Thus, firms are often reluctant to reveal process spectroscopy applications, whether successful or not. Notable exceptions to this include the desire for positive publicity around improved safety or to direct the regulatory environment. Often, companies will patent the work and will not publish in a scientific journal until after the patent is filed, if ever. Many applications, such as the classic titanium oxide-monitoring paper, are revealed only years after implementation. As a consequence, the current state of the art in the literature is quite likely far out of date. 

Consider a process spectroscopy application where all three of the following conditions... 

Crocombe, R.A. and Flanders, D.C., Atia, W. (2004) Micro-optical instrumentation for process spectroscopy. Proc. SPIE, 5591, 11-25. 

Crocombe, R.A. (2004) MEMS technology moves process spectroscopy into a new dimension. Spectroscopy Europe, 16 (3), 16-19. 

Chemical transformation Physical transformation Electrochemical process Spectroscopy Other Physical... 

Miscellaneous other uses of emission spectroscopy should be mentioned. The cement and glass industries use spectroscopic methods for quality control. The food and beverage industries monitor trace element concentrations during processing. Spectroscopy is used for forensic purposes, usually to help identify samples as to source or origin. Meteorite composition also has been studied by spectroscopic methods, as have lunar samples returned to earth by astronauts. Emission spectroscopy also has served as a research tool in chemistry and physics by providing composition information on research samples. 

R. A. Crocombe, MEMS Spectroscopy Moves Process Spectroscopy into a New Dimension, Spectmsc. Eur., 16 16—19 (2004). 

This is the first handbook ever published on electronic and photonic materials, that summarizes the advances made over past the three decades. This handbook is a unique source of in-depth knowledge of molecular design, synthesis, processing, spectroscopy, physical properties and applications of electronic and photonic materials. This handbook contains 73 state-of-the-art review chapters written by more than 180 world leading experts from 25 different coimtries. With over 25,000 bibliographic citations and thousands of figures, tables, photographs, chemical structures, and equations, this handbook represents the work of the most renowned scientists in the international scientific community. It has been divided into 10 parts based on thematic topics ... 

Prior Informed Consent (PIC) Treaty 416 process spectroscopy 218 product composition 407 properties 311... 

Figure 14-7 Fiber-optic probes for process spectroscopy...

The study of food components has been an area of enormous growth for vibrational spectroscopy over the last 15 years. Spectroscopic measurement have provided information on the distribution of fats in certain crops, the percentage concentration of one component with respect to another in other foodstuffs (level of unsaturation), and the concentration of vitamins in mixtures, to name a few. The majority of interest has centered up to now around the use of NIR absorption spectroscopy. Process NIR absorption spectroscopy has been fairly heavily implemented in this area, as can be seen from a review of the Eastern Analytical Proceeding (EAS) proceedings. Ozaki [161] has recently reviewed the use of Raman spectroscopy in the area of food analysis. The reader is referred to this work for a complete review of the area. Only select examples relevant to process spectroscopy are discussed here. 

Current trends in process spectroscopy are (i) measurement techniques with non-invasive possibilities (acoustics, microwave, R, NMR) (ii) measurement techniques with high sensitivity (MS,... 

---