Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Determination of Coloring Substances in Cleaning Products by Chemometrics Methods(01. Izmir Institute of Technology, 2024) Töremen, Çetin; Özdemir, DurmuşBu tez çalışmasında yüzey temizleyici örnekleri incelenmiştir. Bu numunelerin içerisine çeşitli konsantrasyonlarda belirlenen boya miktarları eklenerek hazırlanan numunelere UV-Görünür Bölge Spektrofotometrisi uygulanmıştır. Kısmi en küçük kareler (PLS), basit en küçük kareler regresyonu (SLR) ve genetik ters en küçük kareler (GILS) yöntemleri, bu renklendirici maddelerin kantitatif tayini için hazırlanan numunelerin görünür spektrumlarına başarıyla uygulanmıştır. Bu boyaların ve tek boya içeren temizlik ürünlerinin ikili ve üçlü karışımları halinde toplam 35 adet numune hazırlandı. Bu 35 örnekten 29 tanesi kalibrasyon seti olarak seçilmiş, geri kalan 6 tanesi ise bağımsız validasyon seti olarak kullanılmıştır. Hazırlanan sete 400-700 nm aralığındaki absorpsiyon spektrumları kaydedilerek elde edilen spektral verilere SLR, PLS ve GILS yöntemleri uygulanarak ortaya çıkan tahminler gerçek değerlerle karşılaştırıldı. Bu yöntemlerin (PLS ve GILS) regresyon katsayıları (R²) ve standart hata çapraz doğrulama (SECV) değerleri ile tahminin standart hatası (SEP) bulunmuş, sonuçlar değerlendirilmiş, kemometrik modellemenin doğruluğu gözden geçirilmiş, tahminler ve referanslar karşılaştırıldı. Bu analiz yöntemleri ile kemometrik yöntemlerin UV-Görünür Spektroskopi ile birleştirilmesiyle temizlik ürünlerindeki boyaların konsantrasyonu belirlenebilmektedir.Master Thesis Development of Chemometrics Method Based on Infrared Spectroscopy for the Determination of Cement Composition and Process Optimization [master Thesis](01. Izmir Institute of Technology, 2021) Tepeli, Dilek; Özdemir, DurmuşCalcium, silicon, aluminum, iron oxide-containing raw materials are used in controlled portions to manufacture cement. (How cement Is Made, n.d.) This mixture is first converted to clinker, obtained by heating the mixture to 1500oC; some additives are added and ground to obtain cement. Depending on the purpose, various types are produced, and therefore, the determination of cement composition is an essential task for the quality consideration and the sustainability of the production processes. The quantitative analysis of cement is performed with X-ray fluorescence spectroscopy. However, XRF generally requires tedious and lengthy analysis times. In this study, quantitative determination of the raw materials, intermediate products, and types of cement by using Fourier transform infrared spectroscopy coupled with chemometrics multivariate calibration method is aimed, which could be an alternative for the current XRF technique. Samples were collected from a local cement factory that has been in the sector for several years. Reference analyses of the samples were performed at the quality control laboratory of the same factory. The same samples were analyzed by the FTIR-ATR spectrometer. The resulting FTIR spectra combined with XRF reference composition data were used to construct calibration models using the partial least squares method (PLS). Based on the obtained results, the proposed method could generate quite successful results for the quantitative determination of all types of products used to produce cement. The regression coefficients (R2) of the PLS models vary from 0.95 to 0.99. The standard errors of cross-validations were found as from 0.21 to 1.42 (w/w%).Master Thesis Development of Molecular Fluorescence Spectroscopy Based Multivariate Calibration Models for Quantitative Determination of Fatty Acids and Triacylglycerol Compositions of Olive Oils(01. Izmir Institute of Technology, 2020) Hedef, Onur; Özdemir, DurmuşThis study illustrates the quantitative determination of fatty acid and triacylglycerol composition of olive oils by using multivariate calibration methods namely partial least squares (PLS) and genetic inverse least squares (GILS) coupled with molecular fluorescence spectroscopy. The reference analysis of the olive oils was carried out with gas chromatography (GC) and high-performance liquid chromatography (HPLC) for the compositions, respectively. A total of 125 olive oil samples were collected from Marmara and Aegean olive growing regions in western Turkey, right after the olives oils are produced in the 2010 -2011 season. Chromatographic and fluorescence analyses were performed simultaneously on the samples and then collected spectra were combined with reference analysis results for the multivariate calibration step. Among the several components analyzed by both GC and HPLC, 10 components from fatty acids and 10 components from triacylglycerols were chosen for modeling. Multivariate calibration models were constructed by randomly selecting 100 samples as calibration set and assigning the remaining 25 samples to the independent validation set using PLS and GILS with leave one out cross-validation based on the fluorescence spectra of the olive oils. The results have demonstrated that the compositions could be successfully determined by using molecular fluorescence spectroscopy. The standard error of cross-validation (SECV) and standard error of prediction (SEP) values were acceptable for most of the components. The regression coefficients (R2) of reference values vs. predicted values ranged from 0.70 to 0.98, indicating that molecular fluorescence spectroscopy combined with multivariate calibration could potentially be used for quantitative determination.Master Thesis The Development of Chemometric Methods Based on Molecular Spectroscopy for the Standardization of Production Processes and Product Traceability of Personal Care and Cleaning Products(Izmir Institute of Technology, 2019) Çiftçi İlmek, Berfu; Özdemir, DurmuşPersonal care and cleaning products are the main consumer goods. Changes in our heath caused by all of the chemicals that we exposed to everyday if these products are not produced according to the regulations and determined formulations. Because of this reason, quality control of the product formulation quantitatively is very important. There are some analytical methods for the determination of anion active matter, nonionic matter and total active matter in the product mixture. However, these techniques are expensive and do not give accurate results. The purpose of this thesis principally based on development of rapid, accurate and practical infrared spectroscopic technique based on multivariate chemometrics data analysis methods for the standardization of production processes and product traceability of personal care and cleaning products. In this thesis, two different products are studied which are namely liquid soap and shower gel. Fourier Transform Infrared spectroscopy coupled with Attenuated Total Reflectance accessory based chemometrics multivariate calibration models were developed for the quantitative determination of liquid soap and shower gel compounds. Genetic Inverse Least Squares was used as the chemometrics method for the development of multivariate calibration models in the quantitative determination of liquid soap and shower gel compositions. Standard error of cross validation and standard error of prediction values for content of the liquid soap samples were found 0.26% and 0.21 % (w/w %), respectively. Standard error of cross validation and standard error of prediction values for content of the shower gel samples were found 0.27 % and 0.30 % (w/w %), respectively.Master Thesis Determination of Total Acid Number in the Optimization of Oleate Production by Using Fourier Transform Infrared Spectroscopy and Multivariate Calibration(Izmir Institute of Technology, 2019) Toygar Türkün, Nihan; Özdemir, DurmuşPolyethylene glycol oleate (PEG-Oleate) is a non-ionic surfactant, and is an important emulsifier for water-oil systems. It is produced by reacting oleic acid and polyethylene glycol (PEG) under vacuum for around 4 hours and at 160 °C, in the presence of acid catalyst which is para toluene sulfonic acid (PTSA). The quality and process control of this production is determination of total acid number (TAN) by the standard method ASTM D974 which is a color indicator titration. Although titration is a simple method, it is relatively time consuming and prone to human error. Besides, the solvents used in titration method, are significantly unhealthy for humans. The aim of this study is to develop fast and simple procedure for the determination of total acid number based on Fourier Transform Infrared Spectroscopy (FTIR) combined with multivariate calibration methods namely Genetic Inverse Least Squares (GILS) and Partial Least Squares (PLS). The reference total acid number of the samples collected during the esterification reaction, had been carried out by the ASTM D974 standart method and the Fourier Transform Infrared (FTIR) spectra of the same samples were also collected simultaneously with single reflection diamond Attenuated Total Reflectance (ATR) accessory. Univariate calibration was applied on a specific wavenumber corresponding to the ester peak around 1739 cm–1. Although the changes in the ester peak was showing an inrease associated to the esterification of the reactants, the results of the univariate calibration was unsucsesful. The best regression coefficient was found to be 0.997 by GILS method along with SECV and SEP as 2.295 and 2.694 mg KOH/g, respectively. The results of GILS showed that it is possible to monitor esterification process of PEG oleate.Master Thesis Development of Chemometric Calibration Toolbox and Its Application for Determination of Slep Adulteration(Izmir Institute of Technology, 2018) Akkoç, Gün Deniz; Özdemir, DurmuşA chemometric calibration toolbox, which contains Inverse Least Squares (ILS) regression, Principle Components Regression (PCR), Partial Least Squares Regression (PLSR), Genetic Inverse Least Squares (GILS) regression, and Ridge regression, was developed in MATLAB environment. During the development, multiple strategies to improve the calculation speed, namely vectorization and parallelization, were employed. Besides these programmatic strategies, efficient cross-validation (CV) procedures were implemented that are specifically tailored for parameter tuning of PCR and PLSR. For GILS, by constructing CV matrices in advance, the computational cost was further reduced. Additionally, a Graphical User Interface (GUI), which also includes baseline correction and variable range selection capabilities, was developed. For increased convenience, regardless of the chosen model, the toolbox returns a single vector of regression coefficients that accounts for centering and scaling of variables along with variable selection. Using the developed toolbox, quantitative determination of salep adulteration was carried out through chemometric calibration methods on Mid-IR data obtained from FTIRATR which is a fast and easy-to-use spectroscopic instrument. The main motivation was the lack of an established method for determination of adulteration of salep which can be quite common due to very high price of pure salep, despite the strict legal regulations. Using 365 samples covering a wide range of adulteration scenarios with 20 adulterants, calibration models were obtained and evaluated. Ensemble model, obtained by averaging GILS and Ridge, yielded the best RMSEP of 6.82 (w/w %). To cope with the unspecific adulterant problem, SIMCA was employed to provide an qualitative insight about the presence of such compounds.