Sharif Digital Repository

Progress in analysis of multicomponent mixtures and processes focused on the interpretation of the multivariate responses, rely on the combination of sophisticated instrumental techniques and suitable chemometric methods. Among the present chemometric method, curve resolution techniques have a wide application in the analysis of multicomponent mixtures and processes. Chemometric resolution techniques are used in the present work. At the first, Essential oil of green and black cardamoms was extracted by hydrodistillation and was analyzed by gas chromatography–mass spectrometry (GC-MS). Due to the fact that the essential oils are complex mixtures, strong overlap is observed between the peaks.... 

Regarding the importance of biological systems in daily life and the complexity of these systems, this project is concerned with this problem and especially with applications of chemometrics in proteomics. In this respect, specific importance of peptides has been taken into account in the process of construction of especial and necessary proteins for human body. Due to the risks involved in some experimental investigations, it is quite preferable to utilize modeling approaches using different sets of data. Achieving a number of specific descriptors, a powerful can be established. This model could be quiet comprehensive for the prediction of the electrophoretic mobility of peptides. This... 

Recently, the use of mass spectrometry imaging (MSI) has been introduced as a powerful tool to study the compounds in biological and environmental samples. The lack of need to sample preparation have made it possible to quantify and qualify these compounds in complex matrix such as biological matrices. This technique will also allow analyzing the compounds in a very wide mass range and precise structural information this method gives leads to employ this method widely for quantification and qualification of wide variety compounds. Accuracy and precision of results obtained by this method beside unique information it gives about system lead to wide use of this method in scientific... 

The main aim of this study is developing a robust QSAR model for describing and predicting the inhibitory activities of O-(2-phthalimidoethyl)-N-substituted thiocarbamates derivatives as novel HIV-1 non-nucleoside reverse transcriptase (HIV-1 NNRTIs) inhibitors. These drugs change the active site of the reverse transcriptase enzyme, and finally halter the HIV reproduction cycle. As the first step of this study, a multiple linear regression (MLR) model was built but it has no satisfied prediction ability. As a next step, the nonlinear correlation of the molecular descriptors and activities has been investigated by using artificial neural networks (ANN). In this section the effects of variable... 

In this study, a new strategy based on chemometrics and extraction method of Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) combined with dispersive liquid–liquid micro-extraction (DLLME) in addition gas chromatography-flame ion detector (GC-FID) has been developed for the determination of ten pesticides in complex samples (such as tap water and milk).In this regard, experiments were designed, modeled and optimum condition was achieved by using central composite design (CCD), backward multiple linear regression (MLR) and Nelder-Mead simplex optimization. On this matter, 36 experiments for 5 extraction factors in 5 levels were generated. Also, multi-response optimization using... 

The present research devoted to the application, development and implementation of clustering, classification and regression techniques for modeling of the biological activity of different drug and drug-like molecules. At first, the prediction ability of Bayesian regression techniques was evaluated for describing and predicting the inhibition behavior of Integrin antagonists. As a next step, the complementary local search techniques have been used for improving the performances of Bayesian regularized genetic neural network (BRGNN) algorithm. The results indicated that the pattern search algorithm has a great potential to be used as a feature selection method in Chemoinformatics. In line... 

In recent years, comprehensive two-dimensional gas chromatography (GC×GC) have emerged as a powerful technique suitable for the separation of complex mixtures because of their higher resolution and higher peak capacity. The invention of GC×GC is a milestone development in chromatographic history. However, one of the main challenges in chromatography and especially in GC×GC is related to the difficulty on the analysis and interpretation of the enormous amount of data obtained in these cases. In this context, resolution, identification and quantification of target compounds in the presence of interferences are issues which have a great importance and not totally solved yet. The present... 

Ionic liquids due to their unique physical and chemical properties are widely used in various fields of chemistry and chemical engineering. Determining properties of ionic liquids can be difficult, time consuming or even impossible. In first step of this study the IL thermo database was chosen as source of experimental data of ionic liquids. Viscosity, density, surface tension and melting temperature of ionic liquids based on bis(trifluoromethylsulfonyl)imide anion with cations imidazolium, pyridinium, pyrrolidinium, piperidinium and ammonium were modeled using QSPR approach. Linear and nonlinear models were built by means of multiple linear regression (MLR), multilayer perceptron neural... 

In recent years, with increasing spills of oil and related petroleum products in the marine environment , the need for source identification of crude oil is increasing rapidly. Oil spill can have serious biological and economic impacts. There are many oil tankers on the surface of the sea and 0.68х109 kg crude oil spilled into soil per year . The source identification of oil spills can be a considerable challenge so these studies analytically and environmentally are important. The purpose of this study was to provide an update of the state-of-the-art of oil fingerprinting techniques to demonstrate the use of a rapid, inexpensive and useful technique for distinguishing between crude oils. In... 

Chemometrics is an interdisciplinary subject which has many applications among science and industrial process. Environmental chemist, Food chemist, biologist and so on depend on good analytical chemistry measurement and so need chemometrics to interpret their data. In this project, we have developed different chemometrics and machine learning methods for considering the quantitative structure-activity relationship between different drug-like molecules. Also some chemometrics techniques were applied for the pattern recognition of NIR data on human plasma for discriminating between healthy and infected HIV-1 patients. At first, Quantitative structure-activity relationship (QSAR) models for... 

The purpose of this study was to investigate the capability of Isotopic Ratio Mass Spectrometry (IRMS) in the detection of four common natural plant frauds in saffron, namely Marigold flower, Safflower, Rubia and Saffron Style. For this purpose, first natural saffron isotopes were analyzed and used to investigate fingerprints of carbon-13 and nitrogen-15 isotopes by Elemental Analyzer Isotopic Ratio Mass Spectrometry (EA-IRMS) and carbon-13 isotopic ratio of saffron components by Gas Chromatography Isotopic Ratio Mass Spectrometry (GC-C-IRMS). Then, according to the isotopic behavior of the original saffron, they were sampled to form a mixture of saffron that is representative of the... 

Nowadays, with increasing concerns about health of food and its influence on human health,food authenticity has become a vital issue and a major challenge for consumers and regulatory agencies. It's especially remarkable about food with high nutritional and economical value. On the other hand, solving these challenges necessitates the use of fast and reliable techniques.Among the various foods, saffron is the main candidate for food adulteration due to its low production and high economic value and from this viewpoint it's in fourth place. Since the scope of fraud in this food is vast and also Iran is the major producer of saffron in the world,the present project has highlighted the... 

The emerging field of “metabolomics” focuses on investigating into the changes of low-molecular-weight – less than 1500 Daltons – molecules, or metabolites, and it has significantly developed in the field of detecting diseases, particularly cancer in recent years. Regarding the importance of breast cancer (BC), especially among women, developing simple, trusted metabolic approaches are crucial. In the present work, utilizing multivariate class-modelling techniques combined to nuclear magnetic resonance (NMR) in order to predict breast cancer based on analyzing the blood serum of healthy and BC patients is presented. To do so, using 42 blood samples, 18 BC patients and 24 healthy individuals,... 

These days, food authenticity has become a major challenge because food health directly affects human health. The importance of authenticity is highlighted when we are faced with foods with higher nutritional and economic value. Saffron is an important example of spices because in addition to having food coloring and flavoring properties, it also has numerous health benefits, but it has limited production and high price. Therefore, with the options available and cheaper to be replaced. Thus, among the various spices, cheating in saffron has the fourth place. Hyperspectral Imaging (HSI) has been developed for food safety industrial applications. This technique combines spectroscopy and... 

Breast cancer is one of the most known types of cancer. About every eight women, one woman will suffer from one of the types of malignant tissues during her life. Diagnosing this type of cancer in the early stages is an important matter and can lead to full recovery. Therefore, one of the challenges in this field is the emergence of a fast method with high sensitivity to diagnose this disease in its early stages. Currently, biopsy is the standard method for breast cancer diagnosis. However, there are some drawbacks to this method. For instance, in order to detect the tumor margin, all breast tissue must be removed, which causes all breast tissue, including healthy tissues, to be removed.... 

Today, with increasing concerns about the health of food and its effects on human health, ensuring the quality of food has become a big challenge for regulatory institutions. This issue is more important in the case of foods that have high nutritional and economic value. Among different food items, saffron is especially important due to its low production rate and high economic value. In this research, a new approach based on the diffusion liquid-liquid microextraction method (DLLME) along with gas chromatography-flame ionization detector (GC-FID) combined with chemometrics techniques has been developed to measure the amount of two pesticides in saffron. In this regard, in the extraction... 

The use of hyperspectral images to detect food fraud has become popular and it is necessary to develop chemometrics methods for analyzing the data from these images. Additionally, food authenticity has become a major challenge, and the focus of this thesis is on developing multivariate methods in chemometrics to extract useful information from data obtained from food authenticity verification using hyperspectral imaging (HSI). This thesis consists of six chapters. In the first chapter, a brief introduction to the fundamentals of hyperspectral imaging and food authenticity verification is presented. In the second chapter, the data structure of these images and chemometric methods including... 

In recent years, studying of biological tissues by mass spectrometry imaging (MSI) has been considered due to its selectivity in identifying different compounds in biological tissues, no need for sample preparation, and the possibility of creating the distribution map of these compounds. The complexity of biological tissues due to their heterogeneity, the large volume of data generated, and the effects of competition of other species for ionization in MSI experiments have doubled the importance of using chemometrics to interpret these data. The aim of this work is to quantitatively study Chlordcone as a carcinogenic pesticide and to extract its spatial distribution pattern in mouse liver... 

In recent years, comprehensive two-dimensional gas chromatography (GC×GC) has been widely used, especially in the separation and measurement of complex mixtures, due to its features such as higher peak capacity and better resolution in separation than usual chromatography methods, which the mixture analysis of polycyclic aromatic hydroarbons (PAHs) compounds have been targeted in this study. One of the main challenges in this field is the large amount of data and the qualitative and quantitative interpretation of the resulting data. Therefore, the identification, separation and quantitative measurement of species in this field is important, especially in the presence of interference in the... 

The need to measure the authenticity of food has always been an important concern of many countries. Since food fraud can cause serious problems, every year, much research is conducted in the field of food authenticity all over the world. Milk among dairy products and orange juice among fruit juices are two categories of widely consumed beverages all over the world, therefore they are exposed to various frauds from the manufacturers. Frauds such as adding water to milk and preservatives such as hydrogen peroxide, formaldehyde, and sodium hypochlorite are common frauds that are added to milk to increase its volume and storage time. Among the common cases of adulteration in orange juice, we...