The role of lutein in human body and determination of its concentration in eggs by UV-VIS spectrophotometry

Abstract

Lutein je pigment koji pripada skupini karotenoida ne-provitamina A kao i njegov izomerzeaksantin. Ljudski organizam ga ne može sintetizirati kao biljke, pa ga mora unositi hranom budući da mu je potreban za normalnu funkciju. Najveća koncentracija luteina u čovjeku se nalazi u žutoj pjegi gdje služi kao zaštita od zračenja visoke energije pa njegov nedostatak može uzrokovati probleme s vidom. UV-VIS spektrofotometrija je analitička metoda pogodna za kvalitativnu i kvantitativnu analizu. Apsorpcijski maksimum luteina je na valnoj duljini od oko 445nm što pripada vidljivom djelu spektra što ga čini pogodnim za proučavanje ovom metodom. Standardnim otopinama luteina različitih koncentracija su snimljeni apsorpcijski spektri te je ovisnost koncentracija i apsorpcije prikazana baždarnim dijagramom. Lutein je izoliran iz žumanjaka domaćih i komercijalnih jaja pomoću acetona te je otopljen u heksan-etil acetatu. Svakom uzorku je spektrofotometrijski određena apsorbancija te je pomoću baždarnog dijagrama određena koncentracija. Dobiveni rezultati ukazuju na puno veću koncentraciju luteina u domaćim jajima nego u komercijalnim. Cilj ovoga istraživanja je spektrofotometrijski odrediti koncentraciju luteina iz žumanjka jaja, komercijalnih i domaćih, te usporediti dobivene rezultate.Lutein is a pigment belonging to the non-provitamin A carotenoid group as well as its isomeric zeaxanthin. The human organism can not synthesise lutein as a plant, so it must be taken in by food as it is needed for a normal function. The highest concentration of lutein in humans is in the macula where it serves as a protection against high-energy radiation, so the lack of lutein can cause vision problems. UV-VIS spectrophotometry is an analytical method suitable for qualitative and quantitative analysis. The absorption peak of lutein is on the wavelenght of around 445 nm which belongs to the visible part of the spectrum and that makes lutein suitable for analysis whith this method. Standard lutein solutions of different concentrations are captured by absorption spectrum and the dependence of concentration and absorbency is shown by a calibration diagram. Lutein is isolated from egg yolks of domestic and commercial eggs by acetone and dissolved in hexane-ethyl acetate. Absorption of each sample was spectrophotometrically determined and concentration was calculated using the calibration diagram. The obtained results indicate a much higher concentration of lutein in domestic eggs than in commercial. The aim of this study is to determine the concentration of lutein in commercial and domestic egg yolks and to compare the results