FT-IR spectrometry

The aim of this work is the determination of several nutritional parameters, such as Energetic Value, Protein, Fat, and Carbohydrates content, in commercially available yoghurt samples by using Attenuated Total Reflectance Fourier Transform Infrared (ATR-FT-IR) spectrometry and a partial least square approach. 

Fourier transform infrared (FT IR) spectrometry has been extensively developed over the past decade and provides a number of advantages. Radiation containing all IR wavelengths (e.g., 5000-400 cm1) is split into two beams (Fig. 3.5). One beam is of fixed length, the other of variable length (movable mirror). 

II) Chemical characteristics of the oil condition monitoring IR and FT-IR spectrometry by specified chemical groups (oxidation, soot, nitration, sulfation, additives). 

The particle beam LC/FT-IR spectrometry interface can also be used for peptide and protein HPLC experiments to provide another degree of structural characterization that is not possible with other detection techniques. Infrared absorption is sensitive to both specific amino acid functionalities and secondary structure. (5, 6) Secondary structure information is contained in the amide I, II, and III absorption bands which arise from delocalized vibrations of the peptide backbone. (7) The amide I band is recognized as the most structurally sensitive of the amide bands. The amide I band in proteins is intrinsically broad as it is composed of multiple underlying absorption bands due to the presence of multiple secondary structure elements. Infrared analysis provides secondary structure details for proteins, while for peptides, residual secondary structure details and amino acid functionalities can be observed. The particle beam (PB) LC/FT-IR spectrometry interface is a low temperature and pressure solvent elimination apparatus which serves to restrict the conformational motions of a protein while in flight. (8,12) The desolvated protein is deposited on an infrared transparent substrate and analyzed with the use of an FT-IR microscope. The PB LC/FT-IR spectrometric technique is an off-line method in that the spectral analysis is conducted after chromatographic analysis. It has been demonstrated that desolvated proteins retain the conformation that they possessed prior to introduction into the PB interface. (8) The ability of the particle beam to determine the conformational state of chromatographically analyzed proteins has recently been demonstrated. (9, 10) As with the ESI interface, the low flow rates required with the use of narrow- or microbore HPLC columns are compatible with the PB interface. 

Figure 1. Chromatogram of Cytochrome C tryptic digestion mixture. Lettered peaks were analyzed with the use of both PB LC/FT-IR spectrometry and LC/MS.

Particle beam LC/FT-IR and LC/MS spectrometries provide both different and complementary information. LC/MS measurements provide fragment identity and sequence information through an accurate determination of molecular mass. PB LC/FT-IR spectrometry measurements provide information on the solution structure of the peptide that includes residual or chromatographically induced secondary stmcture and aggregation, as well as information on the presence of some amino acid functionalities. The PB technique is especially useful with larger peptides which posses formal secondary structure. 

Bishop, R.T., Turula, V.E., and de Haseth, J.A. Study of Conformational Effects on Reversed-Phase Chromatography of Proteins with Particle Beam LC/FT-IR Spectrometry and Free Solution Capillary Electrophoresis (1996) Anal. Chem., in press. 

Turula, V.E. (1995) Dynamic Solution Conformation of Biopolymers by Particle Beam LC/FT-IR Spectrometry , Dissertation (Ph.D.), University of Georgia, Athens, GA. 

R. Fuoco, P. R. Griffiths, Analysis of polychlorobyphenyls (PCBs) in contaminated soil samples by supercritical fluid extraction/supercritical fluid chromatography coupled with FT-IR spectrometry, Ann. Chim. (Rome), 82 (1992), p. 235. 

Kaiser G., Mayer A., Friess M., Riedel R., Harris M., Jacob E. and Toelg G. (1995) Critical comparison of ICP-OES, XRF and fluorine volatilization—FT-IR spectrometry for the reliable determination of the silicon main constituent in ceramic materials, Fresenius J Anal Chem 352 318-326. 

Crutcher, D., Gervais, R. and Toms, L., Use of FT-IR Spectrometry as a Replacement for Physical Property Testing of Railway Lubricants , Proceedings of the Technology Showcase-Integrated Monitoring, Diagnostics and Failure Prevention Conference, Ed. G. Humphrey, Mobile, AL, pp. 207-216, 1996. 

At the end of a 30-min reaction period, the plasma was switched off and the feed of anhydrous ammonia gas was stopped. The propylene beads were evacuated for am additional 30 min to remove the unreacted species. The beads exposed to ammonia gaseous plasma are referred to as PPB-NH2. To characterize the surfaces of the control and the modified membranes, the FT-IR spectrometry ( Nicolet 7000 Series) with an ATR attachment was used. KRS-5 reflection plate at an incident angle of 45° was employed for FT-IR-ATR work. Control or modified membrane samples were applied on both sides of the reflection plate. Thi allowed spectra of only few micron thick layer of the surfaces contacting the KRS-5 reflection plate to be obtained. Immobilization of albumin onto membrane having surface amino groups has been described (2,3). 

Different apparati with different characteristics can be used for the same analytical method. Sometimes apparati manufactured in the same factory register differences in characteristics. The differences can be due to construction modifications and to the ambient conditions where the apparatus functions, which explains the differences between results obtained using the same apparatus in different laboratories. An example was demonstrated for the Fourier transform infrared (FT-IR) spectrometry technique that was applied for the analysis of aqueous solution.209 After the same aqueous solution determination in various laboratories by different workers with different instruments was produced by FT-IR technique, similar quality analytical information resulted using the same data processing simple linear method calibration. The conclusion is that the FT-IR spectrometer can be unstable... 

U.S. Environmental Protection Agency Test Method 8410 Gas chromatographic/Fourier transform infrared (GC/FT-IR) spectrometry for semivolatile organics capillary column, U.S. Government Printing Office, Washington, pp. 1-18, 1994. 

FT-IR spectrometry is an instrumental technique of analysis that presents significant advantages over other analytical... 

Fig. 8.27 Schematic representation of step-scan time-resolved FT-IR spectrometry.

Jarute G, Kainz A, SchroU G, Baena JR, Lendl B (2004) On-line determination of the intracellular poly(P-hydroxybutyric acid) content in transformed Escherichia coli and glucose during PHB production using stopped-flow attenuated total reflection FT-IR spectrometry. Anal Chem 76 6353-6358... 

Fourier Transform Infrared (FT-IR) Spectrometry has evolved during the last quarter century from a limited and specialized technology to a widely accepted and powerful tool. Although FT-IR was originally the province of astronomers it quickly found application in high-resolution spectroscopy and analytical chemistry. 

FT-IR) spectrometry may be used routinely for the analysis of samples such as synthetic polymers, biopolymers, composites, and complex industrial materials. 

Z. Zhang, Use of FT-IR spectrometry for on-line detection in temperature rising elution liaction-ation. Macromol. Symp. 282, 111-127 (2009)... 

H. Yang and P. R. Griffiths, Anal. Chem., 71, 751 (1999). Application of Multilayer Feed-Forward Neural Networks to Automated Compound Identification in Low-Resolution Open-Path FT-IR Spectrometry. 

Fig. 18. Schematic of the chemical mapping instrumentation in the Mid- and Near-IR Spectral Regions by Hadamard Transform/FT-IR Spectrometry. (Reproduced from [ 126])...

The mono- and binuclear complexes have been analyzed by FT-IR spectrometry (figure 1). The typical bands of each kind of complex are given in table II with their interpretation. 

Due to unsaturation or strain, equilibrium of the interatomic forces on a sur ce is reached by adsorption of surrounding molecules. Therefore, the chemical composition of the fost atomic layer may be different from that of the bulk. The importance of the sur ce with respect to the bulk in nanostructured powders makes the exact knowledge of the sur ce composition critical. Fourier transform infrared (FT-IR) spectrometry is a powerful tool to determine the nature of the chemical sur ce species as well as the reactive sites. As an example of an FT-IR sur ce study, a nanostructured aluminum nitride powder was analyzed and its sur ce was coiiq)ared with the y-alumina sur ce. 

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