Importance of a good analysis must be emphasized especially when concerning possible presence of toxic elements and/or heavy metals in milk powder. Wherein, contamination can take place anytime during processing through contact with the equipment, packaging, storage, and transport, or from the raw milk itself. How the sample was prepared prior to analysis can leave a great impact. Therefore, observing the effects or its lack of, when the parameters are varied during the sample preparation procedure could be of great interest in terms of the probability of being able to evaluate the productivity and efficiency of the method, which could save cost, time, and energy. The method will involve an open wet digestion system. The following parameters will be investigated during the experiment: type of acid for digestion, weight of the sample, volume of the acid and hydrogen peroxide used, time and temperature of the pre-digestion and main digestion processes. The elemental analysis will be made using inductively coupled plasma optical emission spectroscopy (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). Statistical computation will be made to compare the result of the analysis to find the optimal condition for this method.