Determination of micro- and macroelements in nuts by inductively coupled plasma atomic spectroscopy

Sadržaj esencijalnih i toksičnih elemenata u orašastim plodovima (orahu, bademu, lješnjaku, brazilskom i indijskom oraščiću) određen je metodom atomske emisijske spektrometrije uz induktivno spregnutu plazmu. Uzorci su razoreni u uređaju za mikrovalno potpomognuto razaranje, a nakon optimizacije i validacije metode u uzorcima je određen udio Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, Li, Mg, Mn, Ni, Pb, Sr, V i Zn. Udio K i Na određen je plamenom fotometrijom. Točnost metode određena je na temelju iskoristivosti metode koja iznosi: 95 – 131 % za orah, 94 – 104 % za badem, 69 – 120 % za lješnjak, 80 – 129 % za brazilski oraščić i 89 – 110 % za indijski oraščić. Od makroelemenata u orašastim su plodovima najveći udjeli dobiveni za K i Ca, a od mikroelemenata za Fe, Mg, Mn i Zn. Toksični elementi (Co, Ni, V i Pb) prisutni su ispod detekcijskih granica (< 0,025 μg L−1). Rezultati elementne analize su uspoređeni s preporučenim dnevnim unosom elemenata u 100 i 20 g orašastih plodova. U okviru metodičkog dijela rada prikazan je prijedlog nastavnog sata o plazmi kao fizikalnom fenomenu koji će omogućiti uključivanje ovakvih sadržaja u svakodnevnu nastavnu praksu.The content of essential and toxic elements in nuts (walnut, almond, hazelnut, brazil nut, cashew) was determined by inductively coupled plasma atomic emission spectrometry after thorough optimization and validation of the analytical procedure. The samples were digested in a microwave assisted digestion system, and the elements Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, Li, Mg, Mn, Ni, Pb, Sr, V i Zn were quantified. The concentration of K and Na however, were determined with flame photometry. The accuracy of the ICP-AES method expressed by the recovery determined by spiking experiments for micro- and macroelements ranged from 95 – 131 % for walnut, from 94 – 104 % for almond, from 69 – 120 % for hazelnut, from 80 – 129 % for brazil nut and from 89 – 110 % for cashew. The highest concentration among macroelements have been found for K and Ca and among microelements Fe, Mg, Mn i Zn. The toxic elements (Co, Ni, V i Pb) were present in concentrations below LOD (< 28 μg g−1). Based on the results obtained, the intake of essential elements consuming 100 and 20 gram of nuts per day was calculated and compared with their recommended daily intake. In the second part od this thesis one of the possible modern approaches in teaching chemistry for presenting plasma as physical phenomenon has been elaborated