Semiquantitative simultaneous determination of metals in olive oil using direct emulsion nebulization

A simple method for the semiquantitative determination of several metals in olive oil by ICP-MS is described. The formation of olive oil emulsions, as a simplified sample preparation procedure is demonstrated. Optimization of the chemical conditions for the formation and stabilization of olive oil emulsions is reported: pH, emulsifiers, stirring (mechanical and ultrasonic mode) time, reagents and sample volumes. The semiquantitative determination of Ba, Cd, Co, Cr, Cu, Mn, Ni, Tl, Pb, U, V and Zn was carried out by ICP-MS with direct introduction of the emulsions into the plasma after optimization of the instrumental parameters (power, pump flow, nebulizer gas flow, use of auxiliary oxygen flow). Results from spike and recovery experiments at levels of 100 and 200 ng mL(-1) are 93-115% and detection limits based on 3 times standard deviation of the blank (10 replicates) are 0.25-50 ng g(-1) in the olive oil.