In this work several experiments have been performed in order to obtain a homogeneous and stable system with lubricating oils, which could be used as sample preparation for calcium, magnesium
and zinc determination in these samples. The immediate preparation, without using ultrasonic or other mechanical equipment for agitation, was also aimed in order to make the proposed procedure
fast and handy. Different types of solvents, such as iso-pentanol, xylene, n-butanol, n-propanol, as well as the surfactants Triton X-100 and sodium dodecyl sulfate, in different proportions were investigated. The mixtures of the sample, water, solvent and surfactant resulted in emulsions which are rapidly destabilized (phase separation).