Determination of metals in olive oil using atomic absorption spectrometry

Budući da teški metali i elementi u tragovima imaju negativne učinke na oksidativnu stabilnost maslinovog ulja i ljudsko zdravlje, cilj ovog rada bio je odrediti koncentracije metala važnih u procjeni kvalitete maslinovih ulja. Analize teških metala arsena i olova te bakra, elementa u tragovima, u 35 uzoraka maslinovog ulja porijeklom iz Republike Hrvatske provedene su metodama atomske apsorpcijske spektrometrije grafitnom tehnikom. Uzorci maslinovog ulja sadrže visoki udio lipidnih sastavnica te predstavljaju složen organski sustav za određivanje metala, u cilju dobivanja homogene otopine prikladne za određivanje metala grafitnom tehnikom svi analizirani uzorci prethodno su spaljeni mikrovalnom digestijom. Provedenim istraživanjem uočene su prednosti određivanja koncentracije metala grafitnom tehnikom nakon uklanjanja složenog matriksa spaljivanjem uzoraka mikrovalnom digestijom. Niske RSD vrijednosti upućuju na iznimnu/zadovoljavajuću ponovljivost i postupka mikrovalne digestije i određivanja koncentracije metala grafitnom tehnikom. Na temelju dobivenih vrijednosti LOD i LOQ te definirane NDK proveden metode grafitne tehnike mogu se smatrati prikladnim za određivanje analiziranih metala u maslinovim uljima. Koncentracije analiziranih metala u istraživanim maslinovim uljima bile su ispod njihovih najviših dozvoljenih koncentracija definiranih važećim pravilnikom te upućuju na iznimnu kvalitetu hrvatskih maslinovih ulja. Potrebna su daljnja istraživanja u okviru zastupljenosti drugih metala u maslinovom ulju.Since heavy metals and trace elements have negative effects on the oxidative stability of olive oil and human health, the aim of this study was to determine the concentrations of metals important for the assessment of olive oil quality. The analysis of heavy metals: arsenic and lead and copper, trace element, in 35 samples of olive oil, originating from the Republic of Croatia, were performed by atomic absorption spectrometry using graphite technique. Samples of olive oil contain a high proportion of lipid components, and thus represent a complex organic system for the determination of metal. In order to obtain a homogeneous solution suitable for the determination of metal by graphite technique, all analyzed samples were previously burned by microwave digestion. The research has shown the advantages of metal concentration determination by graphite technique after removal of complex matrix by burning samples by microwave-assisted digestion. Low RSD values point out the exceptional/satisfactory repeatability of microwave digestion procedures and the metal concentration determination by graphite technique. Based on the obtained LOD and LOQ values as well as the defined NDK, conducted graphite technique methods can be considered as suitable to determine the analyzed metals in olive oils. The concentrations of the analyzed metals in the investigated olive oils were below their maximum permissible concentrations as defined by the valid rulebook. The presented data point to the exceptional quality of Croatian olive oils. Further research should be conducted to evaluate the presence of other metals in the investigated olive oil samples