At present, FT-IR spectroscopy is mostly used to track relative changes in essental oil, the baseline being the fresh or new oil. By subtracting the spectrum of the fresh oil from its used or in-service oil counterpart, one can spectrally visualize what has changed at a molecular level, including moisture ingression, additive depletion, oxidation, soot buildup etc. Hence the JOAP protocols attempt to standardize the measurement of these changes in terms of absorbance or arbitrary units that can be correlated with machine faults, wear or failure.
This type of spectral information can be rapidly collected on an ongoing basis and via trending can be associated with specific lubricant changes oxidation, soot buildup. With the correct interpretation, lubricant replacement or additive replenishment can be made on the basis of oil condition monitoring rather than simply on the basis of time, thereby reducing oil consumption and machine wear caused by the use of oils which have exceeded their useful life. One of the main limitations of this approach is that the results may be completely off-track if the base oil formulation changes or the reservoir has been topped up with another oil formulation.
Chemometric data analysis is therefore required to extract the information about quality attributes which is hidden in near infrared spectrum. Chemometrcs age of met cover quit a broad range of methods such as exploratory data analysis, patterns reorganization and statistical experiments. The most common used multivariate data analysis techniques applied to principal component analysis.
Advantages and disadvantages of fourier transform spectrometric techniques compared to traditional analytical methods: The advantages of Fourier transform techniques over dispersive instruments have resulted in almost total replacement of the dispersive instruments in spectroscopy. The multiplex or fellgett advantage: In a dispersive spectrometer, wave numbers are observed sequentially. The throughput or jacquinot advantage: In FT-IR instruments there is no need to limit the beam width in order to obtain an adequate resolution. In fact, a circular optical aperture is used in Fourier transform instruments and the beam area is 75 to times larger than the slit area of dispersive instruments.
As a consequence, there is an advantage of increased beam intensity going through the sample and therefore a much higher throughput with a FT-IR than with a dispersive instrument Jacquinot, This difference is due to the fact that the frequency-stabilised helium. Neon laser is used as internal wavelength standard. Therefore the frequency precision is 18 determined by the frequency stability of the laser, which leads to precise and reproducible wavelengths Perkins, ; Frost et al. High and constant resolution: Spectral resolution is a measure of how well a spectrometer can distinguish closely spaced spectral features.
Filter instruments cannot offer high resolution because, in dispersive instruments, resolution decreases as lower frequencies are scanned. Thus it is constant across the scanning range Wilks, Additionally, the instrument computer uses software that can perform data processing such as baseline correction, smoothing, derivatisation or library searching and therefore improve data information. The most attractive advantage of FT-NIR spectroscopy over traditional analytical tools and any other spectroscopic method is probably that the measurements are non destructive and non invasive and that it is possible to use solid.
Samples without pre treatment and therefore without solvents.http://erugasiwun.tk
Fourier Transform Infrared Spectroscopy
This leads to a large increase in the analysis speed compared to traditional analysis methods and decreases the risk of errors due to weighing and dilution operations Trafford et al. The variety in sampling technologies is another attractive feature of NIR spectroscopy. Several accessories are adaptable to a number of situations and can be used with different scanning modes. For instance, fibre optic probes were used already ten years ago for real time analysis Williams and Mac-Peters, and are nowadays often used in the diffuse reflectance mode for routine qualitative and quantitative applications Blanco et al.
Diffuse reflectance is also easily used for off-line analysis for samples contained in simple glass vials Wargo and Drennen, ; Frarake et al. The transmittance mode is more and more widely used for recording spectra from intact 19 tablets Schilling et al. It gives results with a better repeatability and a smaller prediction error than reflectance measurements Corti et al. The transflectance mode, which is a variant of the diffuse reflectance mode, has also been investigated recently. In this case, incident light crosses the sample, is reflected by a reflectance material such as stainless steel or PTFE Polytetrafluoroethylene located on the opposite side and travels back through the sample before reaching the detector Blanco and Villarroya, An important property of the NIR signal is that, because it depends on both the chemical composition and the physical properties of the sample, analysis of these two characteristics can be performed by the same technique Chen and Sqrensen, NIR also has the potential to be used for developing on.
This advantage can be well used in the pharmaceutical or chemical industry to give real time information about processes. On the other hand, there are three main disadvantages of NIR spectroscopy over traditional techniques. First, the development of a NIR method is time.
Fourier Transform Infrared Spectrometry, 2nd Edition
Consuming because it is necessary to analyse several representative samples by a time. Secondly, NIR methods lack robustness: calibrations often need to be updated, e. This is especially problematic with raw material whose quality may vary from time to time leading to false identification of the material. Furthermore, NIR spectroscopy is not very sensitive and it can usually be satisfactorily applied to major components Blanco and Romero, but not to impurities or low dose substances. Other minor disadvantages are the following: First, in contrast to IR spectra, NIR raw spectra exhibit low specificity.
They do not show clear peaks characteristic to a specific compound of interest. Thus, extensive statistical calculations are required to extract useful qualitative or quantitative information Lowry et al. Second, NIR spectroscopy methods are developed using the reference analysis results of the calibration samples.
Thus, the accuracy of the NIR method cannot be better than the accuracy of the 20 reference method. Furthermore, the transferability of NIR methods from one instrument to another is limited due to the frequent need for updating calibrations after routine maintenance or repair of the instrument Wang et al. Finally, the absence of NIR training in pharmacy schools is one of the major obstacles to the acceptance of NIR spectroscopy by pharmacists.
The specialized vocabulary used in the chemometrics world makes things even less accessible for pharmacists. The quality control of natural products such as essential oils, alkaloids phenolic and other biological samples is one of the most challenging tasks in modern analytics. Recent advacesment in analytical instrumentation of NIR principal components analysis and multivariate data processing open new area of application in biological samples.
The ability to monitor rapidly various essential oils, biological samples it possible to efficiently select high-quality single plants from wild populations as well as progenies of crossing experiments. It is very clear that FT-IR routinely used in quality control of food, nutracetical, cosmocetucial pharmaceutical microbiological samples in order to perform fast quality checks of incoming raw materials and continuous controlling of rapid quality parameters. Baranska, M. Schulz, H.
Tips for Preparing Liquid Samples for Fourier Transform Infrared Spectroscopy
Kruger and R. Quilitzsch, Chemotaxonomy of aromatic plants of the genus Origanum via vibrational spectroscopy.
Schulz, P. Rosch, M. Strehle and J. Popp, Analyst, Villarroya, NIR spectroscopy: A rapid-response analytical tool. Trends Anal. Romero, Near infrared transflectance spectroscopy determination of dexketoprofen in a hydrogel. Eustaqutio, J. Gonzalez and D. Serrano, Development and validation of a near.
Infrared method for the analytical control of a pharmaceutical preparation in three steps of the manufacturing process. Blanco, M. Coello, A. Eustaqutio, H. Iturriaga, S. Maspoch and N. Pou, Fresenius identification and quantitation assays for intact tablets of two related pharmaceutical preparations by reflectance near.
Infrared spectroscopy: Validation of the procedure. Oello, A. Iturriaga and S. Maspoch, Development and validation of a method for the analysis of a pharmaceutical preparation by near. Infrared diffuse reflectance spectroscopy. Jager, L. Jirovetz, J. Imberger and H. Dietrich, Therapeutic Properties of Essential Oils and Fragrances. Buttery and H. Sugisawa Eds. Candolfi, A. Massart, Model updating for the identification of NIR spectra from a pharmaceutical excipient.
Applied Spectroscopy, Sqrensen, Determination of marker constituents in radix Glycyrrhizae and radix Notoginseng by near infrared spectroscopy. Fresenius J. Ceramelli, E. Dreassi and S. Matti, Near infrared transmittance analysis for the assay of solid pharmaceutical dosage forms. Gill, C. Luscombe, D. Rudd, J. Waterhouse and U. Jayasooriya, Near infrared mass median particle size determination of lactose monohydrate, evaluating several chemometric approaches.
Fredericks and J. Article Views Altmetric -. Citations Abstract We describe a new Fourier transform infrared FT-IR spectroscopy-based diagnostic approach, which may provide for the first time a rapid, reliable, and inexpensive blood test for scrapie and related transmissible spongiform encephalopathies TSE.
Cited By. This article is cited by 47 publications. Anthony Shaw.
Analytical Chemistry , 83 2 , DOI: Baena, and, Bernhard Lendl. Analytical Chemistry , 76 21 , Janie Dubois and R. Analytical Chemistry , 76 19 , A A. Analytical Chemistry , 75 23 , Renuka Ranjan, Neeraj Sinha. Nuclear magnetic resonance NMR -based metabolomics for cancer research. NMR in Biomedicine , 12 , e A new way of quantifying the production of poly hydroxyalkanoate s using FTIR. Analytical Sciences , 32 , Matthew J. Baker, Shawn R. Developing and understanding biofluid vibrational spectroscopy: a critical review. Chemical Society Reviews , 45 7 , Zimmerman, Igor K.
Raman spectroscopy of blood serum for Alzheimer's disease diagnostics: specificity relative to other types of dementia. Journal of Biophotonics , 8 Lisa M. Miller, Megan W. Bourassa, Randy J. FTIR spectroscopic imaging of protein aggregation in living cells. Scott, W.
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Beale, D. Corol, J. Baker, R. Merits of random forests emerge in evaluation of chemometric classifiers by external validation. Mohammadreza Khanmohammadi, Amir Bagheri Garmarudi. Elodie Scaglia, Ganesh D. Noninvasive assessment of hepatic fibrosis in patients with chronic hepatitis C using serum Fourier transform infrared spectroscopy. Analytical and Bioanalytical Chemistry , 9 , Bio-Raman spectroscopy: a potential clinical analytical method assisting in disease diagnosis.
Analytical Methods , 3 6 , Diagnosis of breast cancer with infrared spectroscopy from serum samples. Vibrational Spectroscopy , 52 2 , Miller, Paul Davies, David R. Brown, Daniel R. As such it was a very exciting time for infrared spectroscopy. Griffiths, Anal. As an editor of the journal, Laitinen must have been aware of the revolution taking place in infrared spectroscopy.
The widespread availability of FT instruments and the use of computers for recording and analysis of infrared spectra, heralded a new era in infrared spectroscopy. Now it was possible to analyse biological molecules, in aqueous media, at fast speeds and at high resolutions that was virtually impossible with dispersive instruments. For example, Stanley Prusiner was awarded the Nobel Prize for Physiology or Medicine in and infrared spectroscopy played an important role in his work. In a section of his Nobel lecture S. Prusiner, Proc. USA, 95 , he states the following:.
Yet in scrapie we were faced with the possibility that one primary structure for PrP might adopt at least two different conformations to explain the existence of both PrPC and PrPSc. When the secondary structures of the PrP isoforms were compared by optical spectroscopy, they were found to be markedly different….
Nevertheless, these two proteins have the same amino acid sequence! It is noteworthy that the abnormal form of the prion protein PrPSc misfolds and forms aggregates that are virtually impossible for characterisation using X-ray crystallography, NMR and CD spectroscopy. In order to overcome this problem, Prusiner and coworkers used infrared spectroscopy to obtain direct evidence for an increase in betasheet structure in the PrPSc aggregates. In recent years infrared spectroscopy is going through a renaissance catalysed by some exciting developments in technology.
This includes the use of the bright synchrotron radiation for recording infrared spectra. Latest breakthroughs also include the development of two-dimensional infrared spectroscopy and the ability to record infrared spectra at ultrafast speeds. There are also some major advances in theoretical analysis that is enabling a better interpretation of the infrared spectra of biological molecules.
Considering these advances, we felt it would be timely to produce a book that brings together some of the key developments in the field. The book is intended for both experts and those who are new to the field of biological infrared spectroscopy. It would be particularly beneficial for graduate students and research scientists in both industry and academia.
Finally, we would like to thank all the authors who have contributed in this volume. Without their cooperation it would not have been possible to accomplish this task. Reaction-induced infrared difference spectroscopy of proteins is reviewed. This technique enables detailed characterization of enzyme function on the level of single bonds of proteins, cofactors or substrates. The investigation of protein structural dynamics on short time scales fs to ps using ultrafast two dimensional 2D-IR vibrational echo spectroscopy is presented.
Under thermal equilibrium conditions, a protein's structure is constantly fluctuating among conformations associated with different positions on the broad rough minimum on the free energy landscape. Although different conformational substates may be apparent in a vibrational absorption spectrum, linear IR absorption spectra cannot provide information on structural dynamics because dynamical information is masked by inhomogeneous broadening of the lineshapes.
Changes in structure manifest themselves through the time evolution of the 2D-IR line shape spectral diffusion. Here details of the experimental method including the pulse sequence, heterodyne detection to provide full phase information, and the extraction of the molecular dynamics from 2D-IR spectra are outlined. The method and the nature of the information that can be obtained are illustrated with four examples: the influence of mutations on myoglobin dynamics, differences between the dynamics of neuroglobin and myoglobin, the effect of the disulfide bond in neuroglobin on its structural dynamics, and how substrate binding to the enzyme horseradish peroxidase influences its structural fluctuations.
The information retrieved from FTIR spectra largely depends on both the quality of the original spectra and on the correction and processing methods. This contribution reviews the entire process driving to a fine and reliable interpretation of the data. One of the major challenges of the post-genomic era is the rapid characterisation of protein structure.
High-throughput structural genomic projects involving X-ray crystallography and NMR spectroscopy are in progress to solve the three-dimensional structures of a large of number of proteins. These techniques have their advantages and disadvantages and cannot be applied to study all proteins, giving sufficient opportunity for other techniques to also a play significant role in proteomics research.
Fourier transform infrared FTIR spectroscopy is one of the techniques that has gained popularity in this area since measurements on small quantities of proteins can be carried out very rapidly in various environments. However, there is a need for improvements in the interpretation of protein FTIR infrared spectra and development of methods for accurately quantifying protein secondary structure from infrared spectra of proteins. Over the years, much progress has been made in this area and here we provide an overview of the major progress made so far, along with their strengths and weaknesses.
The particular focus of the Chapter is on methods used for quantitative prediction of secondary structure from infrared spectra. Vibrational spectra are frequently used for studies of the structure and dynamics of peptides and proteins. Structural interpretation of the experimental data, however, requires theoretical simulation of the spectra for model peptide geometries.