FT-NIR

Figures 9.26(a) and (b) from FT-NIR Application Note (1998) by courtesy of the Perkin Elmer Corporation.

Ajayakumar P.V. Chanda D. Pal A. Singh M.P. Samad A. FT-NIR spectroscopy for rapid and simple determination of nimesulide in rabbit plasma for pharmacokinetic analysis. Journal of Pharmaceutical and Biomedical Analysis, 2012, 58 (1), 157-162. 

However, the most significant practical issue for the implementation of an FT-NIR device suitable for quantitative process analytical applications arises from the need to maintain a very high degree of alignment at the point of recombination of the divided interferometer beam paths -at the exit of the interferometer. 

We have seen that one of the key aspects of Fourier transform NIR analyzers is their control of frequency accuracy and long-term reproducibility of instrument line shape through the use of an internal optical reference, normally provided as a HeNe gas laser. Such lasers are reasonably compact, and have acceptable lifetimes of around 3 to 4 years before requiring replacement. However, we also saw how the reduction in overall interferometer dimensions can be one of the main drivers towards achieving the improved mechanical and thermal stability which allows FT-NIR devices to be deployed routinely and reliably in process applications. 

Figure 5.18 Compact FT-NIR device with integrated VECSL laser metrology.

Fibre-optic Flow Ceiis to Remote FT-NIR Anaiyser... 

Figure 5.34 shows the FT-NIR predictive models for total vol% paraffins, isoparaffins, naphthenes and aromatics and carbon number distribution for a typical naphtha dataset. Since NIRS can be demonstrated to have sufficient hydrocarbon speciation capability to reproduce the analyzis with the same precision as the GC method, but in a fraction of the time, then a useful process analytical goal has been achieved. 

Figure 5.35 Refinery hydrocarbon process analytical applications of FT-NIR.

A further example of process quality monitoring and reactor batch profiling using NIRS comes with oleo-chemical and biodiesel production. An established use of FT-NIR analysis (AOCS Method Cd le 01) is the determination of the key vegetable oil processing parameters - iodine value (IV) and percentage trans fat content (%Trans) (Figure 5.38). 

F.C. Clarke, M.J. Jamieson, D.A. Clark, S.V. Hammond, R.D. Jee and A.C. Moffat, Chemical image fusion the synergy of FT-NIR and Raman mapping microscopy to enable a more complete visualization of pharmaceutical formulations. Anal. Chem., 73(10), 2213-2220 (2001). 

Andersson M, Folestad S, Gottfires J, Johansson MO, Josefson M, Wahlund KG. Quantitative analysis of film coating in a fluidized-bed process by in-line NIR spectroscopy and multivariate batch calibration. Anal Chem 2000 72 2099-2108. Vazquz Elizabeth Rivera Master of Science Thesis, Optimization of Drying-end-points. Measurements for the automation of a fluidized-bed dryer using FT-NIR Spectroscopy, Univ of Puerto Rico, 2004. 

Several new methods and instruments based on infrared spectroscopy are being developed for food applications. Advances in spectroscopic instruments and data analysis have enabled the rapid and nondestructive analysis of cheese parameters in just a few seconds (e.g., Nicolet Antaris FT-NIR by Thermo Electron Corp.). Another recent development is the miniaturization of FTIR instrumentation, which would enable onsite analysis, while the cheese is being produced. The TruDefender FT handheld FTIR by Ahura Scientific, Inc. (Fig. 5.7) is a portable handheld spectrometer that could be applied to food analysis. With numerous developments in FTIR spectroscopy and several potential food analysis applications still unexplored, there is great research potential in this technique that could benefit the industry and research institutions. 

Clarke, F.C. Jamieson, M.J. Clark, D.A. Hammond, S.V. Jee, R.D. Moffat, A.C., Chemical Image Fusion. The Synergy of FT-NIR and Raman Mapping Microscopy to Enable a More Complete Visualization of Pharmaceutical Formulations Anal. Chem. 2001, 73( 10), 2213-2220. 

V(acac)3 has several applications, including its use as a component in olefin polymerization catalysts it is air sensitive, undergoing gradual oxidation in moist air to give VO(acac)2. Commercial V(acac)3 is allowed to contain not more than 2.0 wt% of VO(acac)2. Several spectroscopic techniques, such as IR, ESR and NMR, have been used to study the structure and properties of V(acac)3. IR and H NMR spectrometries were used effectively for determination of VO(acac)2 in V(acac)3 however, IR showed lower LOD . FT-NIR spectroscopy was used for the determination of calcium ascorbate in blister packs, tablets, plastic bottles etc.. ... 

In the late 1980s and early 1990s, interferometer-based instruments were introduced by companies already producing IR equipment Nicolet, Bomem, Perkin-Elmer, and others. Often, these FT-NIR instruments were merely adapted FT-IRs that were already in existence and were not suited for pharmaceutical samples pure raw materials, blends and granulations, tablets and capsules, and larger plastic containers. 

The popularity of interferometers in mid-range infrared has carried over to NIR. The FT-NIR instruments are becoming quite common in the field. Speed and high resolution spectra are the strengths of FT instrumentation. Since most spec-troscopists are familiar with FT-IR instrumentation, it is logical that they would lean toward an instrument that seems familiar. 

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