Microreflectance-FTIR

Andrasko, J. "A Simple Method for Sampling Photocopy Toners for Examination by Microreflectance FTIR." Journal of Forensic Sciences 39 (1994), 226-230. 

Nondestructive Infrared and Supercritical Fluid Technologies. In studies that required nondestructive, in-situ anaiysis with specialty FTIR sampling capabilities, Figure 6 shows the microreflectance-FTIR spectra (1800-1500 cm-1 of a solid propellant at the (a) exterior extruded surface, (b) interior "bulk", (c) end surface and (d) interior "bulk" after exposure to solvent. The peaks labelled RDX and P2 refer to the absorbances due to the energetic component and plasticizer, respectively. 

Polymeric materials that are thermally sensitive require alternative analytical approaches. Again, processing and analysis of the representative sample "as is" can be achieved with varied SF instrumentation and methods. Figure 7 gives the off-line SFE microreflectance-FTIR spectrum of a contaminant removed from a rubber composite product by an SFE in-process treatment at 340 atm (5000 psi) and 100 C over a several hour period. The SFE method used both static (no flow of mobile fluid through the pressurized vessel) and dynamic exposure of the product to a flow of 4-5 mL liquid carbon dioxide mobile fluid at 340 atm (5000 psi). The extracted contaminant was identified as an oligomeric fluorocopolymer based on FTIR spectral library comparisons. Presence of the contaminant was shown to be detrimental to in-Tield performance of the product and efficient removal was needed with an environmentally acceptable process. 

FTIR instrumentation is mature. A typical routine mid-IR spectrometer has KBr optics, best resolution of around 1cm-1, and a room temperature DTGS detector. Noise levels below 0.1 % T peak-to-peak can be achieved in a few seconds. The sample compartment will accommodate a variety of sampling accessories such as those for ATR (attenuated total reflection) and diffuse reflection. At present, IR spectra can be obtained with fast and very fast FTIR interferometers with microscopes, in reflection and microreflection, in diffusion, at very low or very high temperatures, in dilute solutions, etc. Hyphenated IR techniques such as PyFTIR, TG-FTIR, GC-FTIR, HPLC-FTIR and SEC-FTIR (Chapter 7) can simplify many problems and streamline the selection process by doing multiple analyses with one sampling. Solvent absorbance limits flow-through IR spectroscopy cells so as to make them impractical for polymer analysis. Advanced FTIR... 

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