Process analysis infrared spectrometry

The environmental appHcations of infrared spectrometry are many and varied. Many appHcations at industrial sites are analogous to those for on-line process analysis waste streams and recycling processes can be monitored in the same way. Commercial infrared stack-gas monitors are based on either an extractive probe attached to a long-path gas ceU or an open-path (across stack) configuration (69). Stack plume and flare monitoring can be done externally... 

Mass Spectrometers as Process Analyzers. The use of mass spectrometers in process analysis lias not been widespread because nl its perceived complexity and high cost. Technological advancements over the past decade or two have reduced costs and simplified mass spectrometry to the point where it is suitable lor a number of process analytical applications in place of infrared absorption or gas chromatography mass spectrometer is well accepted in such applications hecause of low cosi. good reliability, and ease of cnmpuicr-controllcd interfaces. 

One indication of the developing interest in PATs in the pharmaceutical area is the number of book chapters and review articles in this field that have appeared in the last few years. Several chapters in The Handbook of Vibrational Spectroscopy3 are related to the use of various optical spectroscopies in pharmaceutical development and manufacturing. Warman and Hammond also cover spectroscopic techniques extensively in their chapter titled Process Analysis in the Pharmaceutical Industry in the text Pharmaceutical Analysis.4 Pharmaceutical applications are included in an exhaustive review of near-infrared (NIR) and mid-infrared (mid-IR) by Workman,5 as well as the periodic applications reviews of Process Analytical Chemistry and Pharmaceutical Science in the journal Analytical Chemistry. The Encyclopedia of Pharmaceutical Technology has several chapters on spectroscopic methods of analysis, with the chapters on Diffuse Reflectance and Near-Infrared Spectrometry particularly highlighting on-line applications. There are an ever-expanding number of recent reviews on pharmaceutical applications, and a few examples are cited for Raman,7 8 NIR,9-11 and mid-IR.12... 

Due to the absorption bands in NIR being weaker than in UV-Vis absorption, NIR spectrometry is not as useful for quantitative measurements but offers better qualitative analysis because of improved selectivity. NIR techniques can handle both liquid and solid samples. Near infrared reflectance analysis (NIRA) has found wide application in process analysis, especially for highly absorbing compounds such as foodstuffs Coal, grain, pulp and paper products and some pharmaceuticals can also be determined by NIRA ". The reflectance from the sample is reported relative to reflectance from a standard reference surface. 

Infrared spectrometry is currently exploited in process analysis but less so than near IR and Raman spectrometry. The reasons for this are the strong absorbances of most mid IR bands and the sensitivity of mid IR optical materials to chemical erosion. There is also a relative lack of practical hbre optic options for use in the mid IR range since silver halide and chalcogenide glasses, which cover the whole of the mid IR region, can attenuate the radiation by as much as 95%, even over short distances. Other hbres such as zirconium fluoride cut off below 2500 cm and so the fingerprint region information is lost. 

See also Activation Analysis Neutron Activation. Atomic Absorption Spectrometry Principles and Instrumentation. Atomic Emission Spectrometry Principles and Instrumentation. Chromatography Overview Principles. Gas Chromatography Pyrolysis Mass Spectrometry. Headspace Analysis Static Purge and Trap. Infrared Spectroscopy Near-Infrared Industrial Applications. Liquid Chromatography Normal Phase Reversed Phase Size-Exclusion. Microscopy Techniques Scanning Electron Microscopy. Polymers Natural Rubber Synthetic. Process Analysis Chromatography. Sample Dissolution for Elemental Analysis Dry... 

Ultraviolet (UV)-visible spectrometry, near-infrared spectrometry, mid-infrared spectrometry, and Raman spectrometry have all been used for online process analysis (including inline and noninvasive applications). 

Near-infrared spectrometry This is an alternative for the process analysis of bulk sweeteners, e.g., raw... 

Installing additional accessories in front of the ion source can render analytes amenable to ionization and subsequent mass spectrometric analysis. On-line sample treatment is especially important when analyzing liquid-phase, complex, and/or concentrated samples. For example a thermal vaporizer was used to enable analysis of liquid samples by a process mass spectrometer designed for gas analysis [196], This system has been successfully implemented in the monitoring of an esterification reaction [197]. The obtained data were in a good agreement with those recorded by in-line mid-infrared spectrometry. The setup incorporated a magnetic sector analyzer with two detectors an electron multiplier detector... 

A two-step degradation mechanism for pofycaprolactone has been proposed by Persenaire et al. [42], They studied thermal degradation of PCL by high resolution thermogravimetric analysis (TGA) simultaneously coupled with mass spectrometry (MS) arrd Forrrier transform infrared spectrometry (FTIR). Based on evolved gas analysis by both MS and FTIR it was concluded that the first step was a random rupture of polyester chains via cw-elimination reaction which produced H2O, CO2, and 5-hexanoic acid. The second step is an unzipping depolymerization process at the chain ends with hydroxyl end groups to form e-caprolactone (see Fig. 4.2). 

Cassidy and Niro [13] have applied high-speed liquid chromatography combined with infrared spectroscopy to the analysis of polyoxyeihylene surfactants and their decomposition products in industrial process waters. Molecular sieve chromatography combined with infrared spectrometry give a selective method for the analysis of trace concentrations of these surfactants. These workers foimd that liquid-solid chromatography and reversed phase chromatography are useful for the characterisation and analysis of free fatty acids. 

Multidimensional gas chromatography has also been used in the qualitative analysis of contaminated environmental extracts by using spectral detection techniques Such as infrared (IR) spectroscopy and mass spectrometry (MS) (20). These techniques produce the most reliable identification only when they are dealing with pure substances this means that the chromatographic process should avoid overlapping of the peaks. 

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