| Abstract | Željezo je prijelazni metal s vrlo važnom ulogom u ljudskom organizmu. Jedna od glavnih uloga željeza je prijenos kisika iz pluća do tkiva putem krvi i to kao sastavni dio hemoglobina u eritrocitima te je sastavni dio enzima u različitim tkivima. Većina željeza u ljudskom tijelu nalazi se u eritrocitima kao hemoglobin (Hb), odnosno kao fero oblik željeza (Fe2+) u hemu (slika 1). U jednoj molekuli hemoglobina prisutne su četiri polipeptidne jedinice od kojih svaka veže prostetičnu skupinu koja sadrži hem. Hem se sastoji od tetrapirolonskog porfirinskog prstena koji sadrži željezo kao Fe2+. Svaki hem može nositi jednu molekulu kisika. Mioglobin je također važan protein u mišićima koji prenosi kisik jer u svojoj strukturi sadrži jednu hemsku skupinu u kojoj je prisutno željezo. Enzimi koji sadrže željezo u svojoj strukturi ponašaju se kao prenositelji elektrona te maju ulogu u oksidativnom metabolizmu da prenose energiju unutar stanice, posebno u mitohondriju. Tijelo ne može samo sintetizirati željezo pa ga je neophodno unositi hranom i suplementirati dodacima prehrani. Dodaci prehrane koji sadrže željezo često su u kombinaciji s askorbinskom kiselinom (vitamin C) koja povećava apsorpciju željeza ili u multivitaminskim kombinacijama. Fitati, oksalati, kofein, tanin i neki lijekovi (tetraciklini, penicilamin, fluorokinoloni i teobromin) smanjuju apsorpciju željeza. Preporučeni dnevni unos (engl. Recommended Daily Intake, RDI) željeza je 15 mg, a kod trudnice je povećana potreba.
Današnje tržište sadrži mnogobrojne vitaminske dodatke prehrani koji uglavnom ne podliježu strogim kontrolama kvalitete kao lijekovi. Zbog zdravstvene ispravnosti takvih pripravaka važno je provoditi i kontrolu takvih pripravaka.
Prvi cilj ovog rada bio je validacija dvije analitičke metode, atomske apsorpcijske spektroskopije i UV-Vis spektroskopije za kvantitativnu analizu dodataka prehrani koji u sebi sadrže željezo. Drugi cilj bio je primjena validiranih metoda za određivanje sadržaja željeza u ispitivanim uzorcima dodataka prehrani. Usporedbom dobivenih rezultata zaključilo se o preciznosti i točnosti primijenjenih metoda u svrhu određivanja sadržaja željeza. |
| Abstract (english) | Iron is an essential trace element. It has several vital functions in the body. It serves as a carrier of oxygen to tissues from the lungs through the hemoglobin of red blood cells, as a transport medium for electrons within cells, and as an integral component of important enzyme systems in various tissues. Most of the iron in the human body is found in erythrocytes as hemoglobin (Hb), or the ferrous form of iron (Fe2 +) in heme (Figure 1). There are 4 polypeptide units in a hemoglobin molecule, each of which binds a prosthetic group containing heme. Heme contains a tetrapyrrolone porphyrin ring that contains iron as Fe2 +. Each heme can carry one molecule of oxygen. Myoglobin is also an important protein in muscles that transports oxygen because its structure contains a heme group in which iron is present. Several iron-containing enzymes, cytochromes, act as electron transporters within the cell and their structure does not allow reversible loading and unloading of oxygen. Their role in oxidative metabolism is to transfer energy within the cell and specifically in the mitochondria. The human body cannot synthesize iron on its own, so it must be supplied through diet and supplements. Iron-containing supplements are often combined with ascorbic acid (vitamin C), which increases iron absorption. Phytates, oxalates, caffeine, tannin, and some drugs (tetracyclines, penicillamine, fluoroquinolones, and theobromine) reduce iron absorption. The recommended daily intake (RDI) of iron is 15 mg, but the requirement is increased in pregnant women. There are many vitamin supplements on the market today that are generally not subject to strict quality controls as medications are. Due to the health safety of such supplements, it is important to control such supplements. The first objective of this work was to validate two analytical methods, atomic absorption spectroscopy and UV-vis spectroscopy, for the quantitative analysis of dietary supplements containing iron. The second objective was to implement validated methods for the determination of iron content in the analyzed samples of dietary supplements. By comparing the obtained results, the precision and accuracy of the applied methods for the determination of iron content were concluded. |
