On-line emulsions of olive oil samples and ICP-MS multi-elemental determination

A method has been developed for the on-line formation of olive oil-in-water emulsions and the multi-elemental determination of Al, Ba, Bi, Cd, Co, Cu, Mn, Ni, Pb, Sn and V by ICP-MS. The method proposed involves automation of the sample preparation process and is considerably less time-consuming than other procedures. Various experimental parameters were studied and optimized for the development of the method: emulsifier concentration at the mixing point, emulsifier concentration in the carrier solutions in the valves, injected sample volume and injected emulsifier volume, emulsion formation flow rate, design of the FIA manifold used ( emulsion formation reactor length, size of the different connections) and the radiofrequency power in the plasma. The optimised method was then applied to different samples of virgin olive oil. Good RSD values were obtained and the recovery values were very satisfactory with good agreement between the results obtained with both the calibration methods employed: calibration curve and standard addition.