DETERMINATION OF METALS IN OLIVE OIL BY ELECTROTHERMAL ATOMIC ABSORPTION SPECTROMETRY: VALIDATION AND UNCERTAINTY MEASUREMENTS

The determination of trace metals in organic matrices is still highly demanding despite improvements in analytical instrumentation. The present study was undertaken in order to evaluate electrothermal atomic absorption spectrometry for the determination of cadmium, copper, iron, lead, and nickel in olive oil. A variety of approaches were used. The most suitable digestion procedure was heating the samples at 300 degrees C for 24 hours and ashing in a muffle furnace at 450 degrees C for 16 hours. The validation data were detection limits of 0.2-153ngg(-1); mean trueness on certified reference materials of 81-94%; mean recovery on spikes of 90-120%; and repeatability of 12-53%. The combined relative uncertainty was 0.298-0.766. Oils processed by pressing had higher copper, iron, and lead concentrations than oils processed by centrifugation. The reported method provides an efficient way for monitoring trace metal content during olive oil production.