Determination of copper in biological materials by sensitive absorption spectrophotometry (Doctoral thesis)

Calin, Alexandru

Copper is an essential trace element, which is an important catalyst for heme synthesis and iron absorption. Following zinc and iron, copper is the third most abundant trace element in the body. Copper is a noble metal, like silver and gold. Useful industrial properties include high thermal and electrical conductivity, low corrosion, alloying ability, and malleability. Most of the metallic copper appears in electrical applications. Copper is a constituent of intrauterine contraceptive devices and the release of copper is necessary for their contraceptive effects. The bioavailability of copper from the diet is about 65–70% depending on a variety of factors including chemical form, interaction with other metals, and dietary components. The biological half-life of copper from the diet is 13–33 days with bilary excretion being the major route of elimination. Chronic copper toxicity is rare and primarily affects the liver. Wilson’s disease and Indian childhood cirrhosis are examples of severe chronic liver disease that results from the genetic predisposition to the hepatic accumulation of copper. The serum copper concentration ranges up to approximately 1.5 mg/L in healthy persons. Gastrointestinal symptoms occur at whole blood concentrations near 3 mg Cu/L. Copper accumulation may increase the risk of neurological diseases as Parkinson’s or Wilson’s diseases. Therefore, the determination of copper levels in drinking water, food, and pharmaceutical formulations, biological and other samples is necessary for prevention of copper overload and has attracted considerable attention. For this purpose, several instrumental techniques have been employed, such as graphite furnace atomic-absorption spectrometry (GFAAS), electrothermal atomic-absorption spectrometry (ETAAS), instrumental neutron activation analysis (INAA), high-performance liquid chromatography (HPLC), ion chromatography (IC), voltametry (V), potentiometry (P), fluorimetry (F) and absorption spectrophotometry which was utilized in our laboratory. Our efforts were indeed proved fruitful by choosing di-2-pyridyl ketone(Dpk) as a potent coordination reagent, that gives a very strong absorbance reaction with copper(II). Some method essentials including concentration of ligand, reaction pH, temperature, time required for completion of the reaction, relative chemical affinity between metals and ligand, absorption spectra, slits width and lamp current were investigated in detail to establish the optimum conditions for the method. The most appropriate pH range, where the reaction of copper (II) and Dpk was investigated, was found to be between 3.0 and 6.0. Both acid and alkaline solutions were studied and the results showed that below pH 2.0 and above pH 6.0 the results are not satisfactory. Thus an acetates buffer solution of pH 3.4 was used throughout, to prevent undesirable deviations of measurements. As for any given reaction, among other external factors at room temperature the system was stable in time. Experimental data show that Dpk concentration substantially affects the sensitivity of the method. The optimum concentration of Dpk for a range of copper within 1 to 5 μM was found to be from 30 μM up to 200 μM. For the experiments the Dpk concentration of 30 μM was choose.
Institution and School/Department of submitter: Πανεπιστήμιο Ιωαννίνων Σχολή Θετικών Επιστημών Τμήμα Χημείας
Subject classification: Chemistry
Keywords: Προσδιορισμός Χαλκού,Απορρόφηση,Ευαισθησία,Φασματοσκοπία,Υπεριώδες - ορατό,Διαπερατότητα,Βιολογικά δείγματα,Παρεμπόδιση,Γεωμετρία μορίου
Appears in Collections:Διδακτορικές Διατριβές

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