Real Time Infrared Spectroscopic Monitoring

Introduction to Real Time Infrared Spectroscopic Monitoring... 

M.J. Barajas, A.R. Cassiana, W. Vargas, C. Conde, J. Ropero, J. Figueroa and R.J. Romanach, Near-infrared spectroscopic method for real-time monitoring of pharmaceutical powders during voiding, Appl Spectrosc., 61(5), 490-496 (2007). 

Photo-acoustic spectroscopy (PAS) is a kind of infrared (IR) spectroscopy which is a popular choice for real-time monitoring of VOCs at ppbv levels. Recently there has been a great revival of interest in PAS because it offers much greater sensitivity than conventional spectroscopic techniques. All spectroscopic methods yield quantitative and qualitative information by measuring the amount of light a substance absorbs PAS simply measures this in a more sensitive way. 

Analytical interfaces are integrated into the AuMpRes set-up for at-line analysis by sampling and subsequent chromatography (HPLC) [108], Moreover, this allows online analysis by infrared or Raman spectroscopy. Real-time monitoring of the chemical processes can be achieved via spectroscopic measurements, for which suitable optical flow-through cells have to be installed at selected positions of the micro reaction system. 

Alternatively, samples can be withdrawn from the reactor and analyzed for residual monomer in solution at various times by chromatographic or spectroscopic techniques. Sample removal techniques can be very difficult, especially since many reactions are extremely sensitive to oxygen and other impurities that can be introduced during sampling. In situ infrared spectroscopy is a state-of-the-art, real-time, monitoring technique that is well suited to obtain real-time structural and kinetic information of polymerization processes without sampling. In addition, reactions are analyzed without complicated reactor modifications or expensive deuterated monomers. 

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