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.... 

A novel application of diazonium salts for grafting the sol-gel based sorbents was sucessfully introduced. Preparation of unbrekable sorbents has been on highly demand and sough after by many researches for several years. However, there are a few achivements in this regard, but it still remains as a big challenge.Regarding to this issue, diazonium salts were sucessfully applied for functionalizing the different substrates, in which there is no limitation in selection of substrates. Different substrates, metallic and non metallic, such as copper, brass, stailess steel and PTFE were chosen to be functionalized by chemical or electrochemical reduction of 4-Amino phenyl acetic acid. Then,... 

Considering principles of both micro-solid phase extraction (µ-SPE) and stir-bar sorptive extraction (SBSE) techniques, in this study a microextraction technique was developed using a polypropylene sheet as extracting device for isolation of fluoxetine from biological samples. Being rather inexpensive and simple to prepare extracting device, elimination of time consuming sorbent synthesis step and memory effect are some of the advantages of the proposed method. The extraction process was performed using a polypropylene sheet as extracting device. Solvent desorption was performed in a microvial and then extractant was injected into HPLC system. The effect of various parameters including pH,... 

Thiomersal is an organomercury compound. This compound is a well established antiseptic and antifungal agent. It has been used as a preservative in vaccines, immuno-globulin preparations, skin test antigens, antivenins, ophthalmic and nasal products, and tattoo inks. Thiomersal is very toxic by inhalation, ingestion, and in contact with skin, with a danger of cumulative effects. It is also very toxic to aquatic organisms and may cause long-term adverse effects in aquatic environments.
Thiomersal's main use is as an antiseptic and antifungal agent in vaccines. In multidose injectable drug delivery systems, it prevents serious adverse effects such as the Staphylococcus infection that,... 

Liquid-liquid-liquid microextraction (LLLME) is a new miniaturized liquid extraction to preconcentrate and purify for ionizable analytes. In LLLME firstly analytes extracted in an organic phase, and subsequently back-extracted into a second aqueous phase. Main advantages of LLME are their speed, simplicity, negligible volume of solvents, analytical precision, short sample preparation and low cost. This technique was shown to be an efficient preconcentration method for the extraction of estrone and estriol from biological samples. A basic microdrop in the tip of microsyringe was fixed in the organic layer over the sample solution. After extraction for a preset time, the microdrop was... 

One of the considerable issues in fullereneresearch is low yield of endohedral fullerene production.In this project, synthesis and optimization of endohedral metallofullereneproduction was undertaken byarc reactor applying vertical graphite electrodes, using vaporizing composite lanthanum-oxide-graphite-dopped rod. Increasing the efficiency of endohedral fullerrene production in sootwas followed applyingcarbide formation in electrode which was studied by X-ray diffraction(XRD), thermogravimetric analysis(TGA) and infrared (IR) spectroscopy. In addition, as a simple and fast method, the liquid column chromatography was applied in separation and purification of fullerenes as well as endohedral... 

An on-line solid phase extraction (SPE) method coupled with high performance liquid chromatography (HPLC) was developed using electrospun polyamide (PA) nanofibers as the extractin medium for trace determination of clodinafop propargyl herbicide in environmental aqueous samples. The sufficient numbers of disc sheets were cut from the electrospun PA mat and used as packing material in a cartridge. The homogeneity and the porosity of the prepared PA sheet were studied using the scanning electron microscopy (SEM) and the observed nanofiber diameters and lengths proved that the prepared sorbent possess a high aspect ratio. Major parameters affecting the extraction efficiency were optimized. The... 

A method for determination of estrogens in biological samples was developed. This method was based on high performance liquid chromatography using online micro-solid phase extraction with 25 mg sorbent synthesized by electrospining of silica/PVA nanofibers. Poly (vinyl alcohol) (PVA) is an easily electrospun polymer with unique properties such as biocompatibility, processability, and hydrophilicity. Silica is biocompatible, thermally stable, and comparatively inert. Incorporation of silica with PVA produces hybrids with enhanced thermal and chemical stability in sample media and elution solvents without relinquishing the biocompatibility of PVA. The sufficient numbers of disc sheets were cut... 

In this thesis, a new approach was developed to achieve mechanical and chemical resistant capillary microextraction (CME) in on-line combination with high performance liquid chromatography (HPLC) based on sol-gel technology. This thesis is divided into three chapters:
First chapter contains of two parts. Overcoming the lack of mechanical stability of the substrate of CME by replacing the fused silica by copper tubings was the main objective of the first part. Self-assembled monolayers technique was employed to functionalize the copper tube followed by chemical bonding of the sorbent on the inner surface of the copper tube by sol-gel technology. The prepared copper tube containing the... 

Several metal-organic frameworks based on chromium metal salt and terephthalic acid were synthesized by the solvo-thermal method and modified directly using amino acids or their imidazole derivatives. Suitable characteristics of the synthesized novel MOFs led to their use as novel extracting phases for sample preparation. The sorbent’s performance in extracting anti-hypertension drugs such as eprosartan, losartan and valsartan was tested using the magnetic solid phase extraction which is a form of μ-SPE, followed by HPLC analysis. Different parameters effecting the extraction and desorption procedures were optimized to achieve the highest performance of extraction and sensitivity. Said... 

Factor analysis based methods are one of the applied methods in the Chemometrics. In this regard, some modifications on one of the factor analysis based method named fixed size moving window evolving factor analysis were done and two new methods named variable size moving window evolving factor analysis and preselected variable size moving window evolving factor analysis were introduced. The performance of the new introduced methods were examined and compared by the fixed size moving window evolving factor analysis.
Pure variable selection methods are useful for curve resolution methods which need to define an initial estimate from chromatographic profile or spectra. In this aspect the...