INFRARED SPECTROSCOPY

Author: AZZOUZ TARIK.
Year: 2003.
University: BARCELONA [www.ub.es].
Place of defense: QUÍMICA.
Place of preparation: FACULTAT DE QUÍMICA DE LA UNIVERSITAT DE BARCELONA.

Summary: Various techniques have been applied multivariate calibration, especially the method of partial least squares (PLSR) for the determination cuantitartiva individual different analytes in samples cereales.Se point made both experimental procedures for the quantitative determination of analytes from the measures espectrofotométricas NIR such as procedures for multivariate analysis of data espectrales.Se has standardized quimiometricamente spectra of feed grain measured in different NIR instruments with monocromados high resoluciónl.Se has implemented different methods of data on department data fodder to optimize the best for this type of pretreatment samples. It has used the concept of net analyte signal (NAS) to estimate the parameters of quality (selectivity, sensitivity, accuracy, signal-to-noise limit of determination) in the multivariate calibration reverse. It has extended the application of the method of multivariate curve resolution by alternating least squares (MCR-ALS) to the quantitative analysis of components in complex samples.

Author: Gómez Carracedo María Paz.
Year: 2004.
University: A CORUÑA [www.udc.es].
Place of defense: Facultad de Ciencias.
Place of preparation: Facultad de Ciencias.

Summary: The infrared spectroscopy is a technique used in most industrial environments of the area because of its chemical simplicity of use, low maintenance of equipment, little time spent on analysis and analyzes the sample with little or no manipulation of the same. This project will apply this technique to quality control of two types of industry, petrochemicals (analysis kerosenos) and food (analysis of apple juice). For the particular case of analyzing kerosenos, are going to predict the physicochemical properties of these productgos through direct measurement of the product in the infrared area middle and its combination with multivariate regression (PLS). Different systems will be used for measuring liquid and gaseous samples. The goal is to replace the conventional analytical methods for a faster method, but reliable, and easier to implement. In the case of fruit juices, has selected the apple juice because of the great importance it reaches in Galicia (approximately 59,000 metric tons of production). The main objectives of this project in this section are: 1 .- To develop a systematic analysis rapid, simple and reliable to decide whether the total content of juice declared by the manufacturer in the container label corresponds to the actual content in juice acquiring the consumer. 2 .- To determine whether the technique work provides information on the actual composition of the juice and if it is comparable to the composition of the product "true" or "typical". The methodology used to be: 1 .- infrared spectroscopy in the middle by Fourier transform coupled Reflectance Total Atenuada to measure aqueous samples (IR-FT-ATR). 2 .- Modeling and characterization of samples of samples juice "real" through mathematical models (which would apply statistical techniques typical of the Analytical Chemistry and included under the name of Quimiometría). The modeling was performed using advanced techniques classification: Curves Power, Soft modeling classes (SIMCA), Partial Least Squares (PLS), Networks of artificial neurons (RNA) and techniques for selecting variables (Genetic Algorithms and rotation Procustes) . 3 .- Analysis juice commercial and clasificacidon as models designed.

Author: PEREZ APARICIO JESUS.
Year: 2004.
University: CÓRDOBA [www.uco.es].
Place of defense: E.T.S.I. AGRONOMOS Y MONTES.
Place of preparation: E.T.S.I. AGRONOMOS Y MONTES.

Summary: The spectrophotometry in the near-infrared region has been widely used for determining the composition of many foods. The cause of such widespread use is its low cost, speed and the ability to implement it on production lines. Have a device capable of determining the composition of the product packaging enable numerous applications in the labeling of the product or services for quality control agrifood. This was the fundamental objective of this work. We used cured sausage prepared in a traditional industry of Córdoba (Camilo Rios SA) and the team DA 7000 of Perten Instruments to obtain spectra. The calculation of a model calibration using NIR technology is a process of successive operations whose objective is to relate the whole spectrum and the reference values of the samples. The number of variables (very high) and the characteristics of the NIR spectrum, hinder the development of calibration equations, being very important use of Quimiometría. The rapid development of computers has allowed the creation of almost constant new algorithms increasingly efficient. For the realization of the models are programmed with a caliper program using MATLAB algorithms known and a strategy that makes it possible to visualize if the model is sobreajustado or not by the subsequent validation of the model with previously extracted samples using a variety of criteria. Therefore facilitates obtaining accurate models and the selection of the number of latent variables most appropriate. The models found showed the possibility of developing this technology in the product cured and vacuum packaging which is a major breakthrough in the marketing of products derived from traditional Iberian pig.

Author: URBANO CUADRADO MANUEL.
Year: 2004.
University: CÓRDOBA [www.uco.es].
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: The investigation of this thesis has been dedicated to the use of the latest trends in computational analytical chemistry to improve the analytical process. It is divided into two parts: the first where they have developed aplícaciones software for the automation of the process and to analyze the data it generates, and a second where methods have been developed quimiométricos, both quantitative and qualitative data from spectroscopic . Applications software developed reduced problems in the relationship between analytical chemistry and computing, as are the specific nature of the problem analytical programs, the high degree of dependence on hardware and operating system, weak escalabilidady Finally, the limited involvement analytical chemist in its development. In automation, built platform enables the design and control of the analyzer via graphical interfaces. The design of analizadorse defines the structure and behavior, the latter is based on the value of parameters of state and time, which also specifies the user. The definition of the analyzer is stored in an XML file that is converted into computer commands at runtime. The analytical data management, has developed an information system open to any process and any laboratory, consisting of applications for managing data and for aid to decision making, the tools used (Javay Oracle) claim the independence of the plataformay of where they are accessing the information. Qualitative methods were models for SIMCA differentiation and classification of wines in response to several criteria. We used data UV-Vis and MIR. The ability to develop models from data MIR was possible only with a data processing proposed in this thesis based on fingerprints and calculating similarities. Quantitative methods were PLS equations for the determination of 15 parameters oenological data Vis-NIR. Moreover, compararonlos results obtained using the areas Vis, NIRy MIR.

Author: PEINADO AMORES ANTONIO CLODOALDO.
Year: 2005.
University: AUTÓNOMA DE BARCELONA [www.uab.es].
Place of defense: Facultad de Ciencias.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: The main objective of this thesis is to establish an analytical methodology to follow the process of alcoholic fermentation. The spectroscopy in the near-infrared (NIRS) has been used as a technical instrument to record information in continuous systems fermentativos. To extract useful analytical information, from the spectral information has been used different tools quimiométricas. To achieve the primary objective announced it has been necessary: 1_Establecer different methodologies for determining the main species involved in the fermentation process. The consumption of glucose and formation of ethanol were determined through a system FIA (Flow Injection Analysis) coupled to a UV-VIS detector. Biomass has been determined by the method of the weight of dry matter. The formation of glycerin was determined by gas chromatography and acidification was determined by titración. These methodologies provide analytical information that was used to construct models multivariables. 2_ correlate spectral and analytical information for the five species listed. The models were created through the tool PLS (Partial Least Squares) and validated externally. 3_ Studying the ability of extractive resolution techniques curves narrowly cadrados alternate (MCR-ALS). These techniques were found to be valid for tracking and alcoholic fermentations were applied in monitoring processes fermentativos made at different pH and temperature conditions. 4_ study the effect of temperature on polar liquids and propose a tool to correct the distortions. The combination PARAFAC (Paralell Factor Analysis) and MLR (Multivariate Linear Regression) has been successfully applied to two different sets of data and has corrected the effect of temperature on models created

Author: Valdes Calvino Damarih.
Year: 2005.
University: AUTÓNOMA DE BARCELONA [www.uab.es].
Place of defense: Departamento de Quimica.
Place of preparation: Departamento de Quimica.

Summary: In the last years there has been an increase in the use of near infrared spectroscopy, due to its multiple advantages: it is a non-invasive and non-destructive technique, it requires very little or no sample preparation, the ability to provide measurements and results in a highly expeditious manner, the low cost of analysis, an absence of reagents; as well as the possibility of making simultaneous determination of physical and chemical parameters. Nonetheless, the characteristic of the NIR signal requires the application of multivariate methods to obtain the desired information contained in the spectrum. The spectral variability produced by the insufficient control of physical parameters, gives rise to complex models of calibration as well as a poorer predictive capacity. In an industrial process experimental conditions can not always be strictly controlled and variations of the physical conditions of the system (temperature, pressure, moisture, etc.) often take place. The different arrangement from molecules in a crystalline structure gives rise to the polymorphism and this property complicate the models of calibration of samples in which this property is present. In the pharmaceutical industry is very common that active principles can exist in two or more different crystalline forms (polymorphs). We have taken advantage of these differences for the characterization and determination of different polymorphs of a substance. One of the objectives of this thesis is to develop new methodologies of analysis for the identification and characterization of polymorphs of azithromycin by means of NIR spectroscopy. Models of calibration were developed based on the algorithm of partial least-square (PLS) regression for the determination of a polymorphic form in the presence of another and were validated for their application in the pharmaceutical industry. In addition, a study of stability under high temperature and moisture conditions was carried out to establish the stability of different forms. Temperature changes alter the intensity of absorption bands and shift their position in the NIR spectra for liquid samples. The second objective is to study the effect of temperature on NIR spectra on the ingredients of an esterification reaction over the range 25-90 ºC and to construct calibration models to determine the concentration of the components of the mixtures within the temperature range with a correct predictive capacity. Two strategies were used; one consists of modeling and the other in eliminating the temperature effect. In order to model the temperature effect calibration models were constructed, that implicitly include the variable temperature in different ranges, using the partial least-square (PLS) regression and stepwise principal component regression (MLR stepwise). Another strategy is to eliminate the temperature effect by means of the variable filtering method known as orthogonal signal correction (OSC). Once the spurious spectral information that is unrelated to the concentration of the components of the mixtures was removed, models of calibration are constructed based on the partial least-square (PLS) regression. In conclusion, this thesis provides analytical tools of interest applicable to the pharmaceutical industry for the characterization of polymorphs of azithromycin and the determination of polymorphs mixtures as well as providing a suitable method for the correction of the temperature effect in liquid samples.

Author: Armenta Estrela Sergio.
Year: 2006.
University: VALENCIA [www.uv.es].
Place of defense: FACULTAT DE QUÍMICA.
Place of preparation: FACULTAT DE QUÍMICA.

Summary: One of the main concerns of the Analytical Chemistry today is the development of analytical methods that are environmentally sustainable. Procedures that, without sacrificing features and analytical precision and accuracy, reduce the amount of waste generated in laboratories, methods for other features such as speed and reagent consumption are as important as the previous ones. Here in this thesis has been developed, validated and evaluated analytical tools based on the use of techniques that allow vibrational control products manufactured with different physicochemical characteristics. This has been designed and developed simple point-based direct action and non-destructive of solid samples, thus eliminating altogether the use of solvents and reagents and minimizing the pretreatment of the sample. In the event that direct analysis is not feasible, it has sought to reduce the quantity of solvents used in the extraction process of analyte and the use of less toxic solvents. In the same way automated methods have been developed based on measurements in line may also include stages of sample preparation and / or extraction of the analytes, in a manner that is conducive to the reduction of solvent consumption and also minimizes the contact operator with toxic substances. Also, procedures have been developed based on vibrational spectroscopy allowing the simultaneous determination of more than one active ingredient. It has also demonstrated the usefulness of vibrational spectroscopy for monitoring reactions where it is necessary to control the parameters of quality of raw materials and final products as well as the intermediate stages of the process, so that they can be corrected errors in almost real time while minimizing economic losses.

Author: GARRIDO MARIANO ENRIQUE.
Year: 2006.
University: ROVIRA I VIRGILI [www.urv.cat].
Place of defense: FACULTAT DE QUIMICA.
Place of preparation: FACULTAT DE QUIMICA. URV.

Summary: In this PhD thesis which is entitled: "Monitoring quantitative reactions curing epoxy resins using near infrared spectroscopy and methods of resolution of corners" have raised two broad objectives. The first goal has been proposed to assess the ability of the espectrosocopía of near infrared, assisted by Resolution Multivariante of curves based on the optimization of Minimum Squares Alternados, to track quantitative reactions curing epoxy resins. This objective arises in the first instance, the need to verify whether such a combination of techniques (instrumental and quimiométricas) can detect all sources of variation present in the system under study. Also, in a second step involves the quantitative determination of the evolution of the species involved in the reaction over time, as well as obtain spectral information of all compounds (including intermediate reaction). This is also a study of the uncertainty of the results and validate them. The second objective has been raised to estimate the kinetic constants associated with the reactions of epoxy resins. This implies more about the mechanism of curing process and understand the implications of the same properties of the final product of the polymerization. Epoxy resins are among the most important compounds within the group of polymeric materials. Under the name epoxy resin is often designate both the prepolímero as the final product of the process of curing or polymerization, since both contain its structure epoxide groups. The attraction of epoxy resins is due to the extremely wide range of chemical reactions in which they can take part, and the large amount of material that can be used as a curing agent, which gives rise to different properties in the polymer end . The process of curing epoxy resin directly affects the properties of the final polymer [2-3], which is why there is a need to develop analytical methods capable of monitoring reactions that occur during the process of curing. The Near Infrared spectroscopy is a particularly attractive tool for monitoring reactions cured because, thanks to the low absortividad molar of their signals, allows the study of the process on the spot, without the need for pre-treatment sample [13 , 15.18]. This enables as well as quality control of the proceeds of polymerization in real time, extracting information about the curing reaction. The use of so-called Resolution Methods Curves [19-23] enables a multivariate analysis of the spectral data, obtaining more information about the system under study. A necessary condition in order to apply these methods, also called soft methods of modeling is that the data must have a structure bilinear or tending to the bilinealidad. That is, the matrix of experimental data (matrix intensities response) can be expressed as the product of an array of concentrations by another array containing the signal pure species [24]. Thus, by the decomposition of a matrix of data, resulting in the monitoring of a chemical reaction (eg, a reaction curing), it is possible to know the evolution of each species involved in the process, as well as their for pure spectra. In this Doctoral Thesis, these techniques are applied to data obtained from monitoring reactions of epoxy resins, using near-infrared spectroscopy, for the purpose of obtaining informed 8-úti c49 l both qualitative and quantitative, not only the concentration of the species in the study, but also referring to the reaction mechanism and kinetic parameters. Despite the advantages that involves the treatment of multivariate data spectral there are some typical problems of the structure of the data recorded, as is the case with the rank deficiency [30]. When data systems come spectroscopic chemical evolution, it is common to find this deficiency range, which occurs when the number of sources of variability observed is less than the number of species that absorb in this spectral region [31]. During the development of this thesis apply two different strategies for solving this problem. Another characteristic that occurs when the decomposition of matrices bilinear data is the presence of so-called ambigà ¼ ages rotational and intensity [21]. This means that, instead of obtaining unique solutions for the resolution of a given data set, you get a set of solutions, which in accordance with the experimental data with a single minimum residual. Part of the work is involved in estimating these ambigà ¼ ages solutions and minimization of the same. The results obtained by combining near-infrared spectroscopy and modeling methods have been soft contrasted with reference techniques already in place for monitoring this type of reactions, such as high efficiency liquid chromatography (HPLC) [5.10] and with other techniques for use in the quantitative monitoring reactions of epoxy resins is unprecedented, as is the case with the Nuclear Magnetic Resonance of 13C. It has also conducted a study of kinetic reactions studied, which involves the identification of the reaction mechanism and the proper delivery of kinetic parameters partners, namely the constant speed of reaction. The kinetic study has been carried out by applying different combinations of soft modeling techniques and modeling drive. In implementing these strategies have earned the kinetic constants for reactions of various epoxy resins. In addition, it includes a brief discussion about the possibility of extrapolating the techniques used to model systems to systems epoxy-amina that react to form a dense network interwoven.

Author: GONZÁLEZ ALONSO CRISTINA.
Year: 2006.
University: COMPLUTENSE DE MADRID [www.ucm.es].
Place of preparation: INSTITUTO PLURIDISCIPLINAR.

Summary: Air pollution, today, is responsible for some purpose in nature that have the greatest impact for life on Earth. Understanding the dynamics of the pollutants responsible for such purposes, it could pose measures to help control and reduce air pollution. The technique of remote sensing laser radiation, lidar, enables the determination of atmospheric constituents. The differential absorption lidar (DIAL) is a selective and sensitive methods to carry out such determinations. The ozone and ethylene are two constituent tropospheric that in certain concentrations, cause damage to living organisms and materials present in the earth. Both pollutants are linked to activities typically attributable to humans, as is the intensity of traffic. A lidar system that emits Dial-in the region of the IR remote has been conducted actions of these two species. Based on the results obtained a correlation between the number of vehicles per hour and the temporal evolution of these two pollutants. The development of a kinetic model allows corroborates the existence of a direct correlation between ozone and ethylene; species that are correlated between iya turn correlated with another group of compounds also very important for the whole atmospheric chemistry: nitrogen oxides. The correlation between these three parties is verified using a linear model of disturbance.

Author: Castillo Martínez Miguel Jorge.
Year: 2006.
University: AUTÓNOMA DE BARCELONA [www.uab.es].
Place of defense: Universidad Autónoma de Barcelona.
Place of preparation: Universidad Autónoma de Barcelona.

Summary: The thesis is dedicated to the study of the application of spectroscopy in the near-infrared (NIR) in the monitoring and control of chemical processes, proposing appropriate methods for the control analytical parameters of reaction and / or monitoring of species involved in the reaction, quickly, without sample pretreatment and without the use of toxic reagents or solvents. Different models have been developed for monitoring calibration of the components involved in the reaction of esterification between glycerine or other alcohols and acids long chain. The reaction between industrial esterification mixture of glycerin and caprylic acid and cáprico for obtaining controlling triglyceride often starting with the index acid (IA) and the rate of hydroxyl (IOH), and slow methods that require the use of toxic reagents and solvents. These two parameters have been determined by applying multivariate calibration models built from samples extracted from the process, which saw its spectrum NIR at-line and identified by the relevant reference methods. Models have been constructed calibration PLS1 for IOH, IA and water, which can be used in controlling these three parameters quickly and without consumption of reagents. When this reaction is carried out with excess glycerin, the product obtained is a mixture of mono-, di-and triglycerides, which requires the development of model calibration for each of these species. From samples of the process, samples prepared in the laboratory and associated reference values obtained by gas chromatography were prepared models PLS1 each component, which allows the determination of the species involved in the reaction from a single NIR spectrum, reducing considerably the time of analysis in comparison to other instrumental techniques. The reaction with excess glycerin was studied later by Resolution Multivariante of Curves (MCR-ALS). Using the profiles of the species concentration obtained by gas chromatography as restrictions on equality were obtained pure spectra of the species involved in the reaction to the species of which was not available patterns for a proper level of purity. These spectra were subsequently used for the estimation of concentration profiles in new processes in this way requires little reference information, which is an advantage for the development of model calibration and for the study of evolutionary processes. Subsequently, we studied the process for obtaining triglyceride. In this case, they used pure spectra of the system components as initial estimates in the iterative process, and include a minimum of quantitative information as a restriction of equality. The concentration profiles obtained allow to establish the evolution of individual species and also calculate the values of AI and IOH. The results obtained by MCR-ALS for predicting external samples are comparable to those obtained by PLS in terms of RSEC / P (%), with the important advantage that CFR requires less data to develop models. A similar methodology of work followed in the study using in-line NIR spectroscopy of the reaction of esterification between Myristic acid and isopropanol. We studied the application of this technique to obtain the concentration profiles without the need to use analytical techniques reference profiles obtained concentration of the species involved in the reaction after only NIR spectral information. The profiles obtained were used to calculate constant speed, stating that the reaction follows a kinetics pseudo-primer order and that depends on the speed of addition of isopropanol and the water content of it. The method NIR-MCR proposed to determine the influence of experimental parameters, quickly and efficiently, without the need for reference analysis. Finally, we studied the effect of two pretratamientos spectral, the CSO (8 Orthogon 671 to Signal Correction) and NAS (Net Analyte Signal) for the construction of model calibration PLS at concentrations close to the detection limit, concluding that both have a high ability to eliminate signal not related to the analyte studied, but do not improve the predictive power of external samples. This study has been completed with the calculation of the limit of detection of PLS model developed using two methodologies. Both allow the estimated detection limit in multivariable models calibration easily, and the results confirm previously commented. This thesis provides analytical tools rapid, economic and robust for use in the chemical industry in the control of chemical processes and conducts a study of the application of new techniques quimiométricas to control processes through the application of NIR spectroscopy and techniques of Multivariate spectral data handling.