ICP-MS and EDXRF are suitable for determining the major elements in oil ashes. However, EDXRF has many advantages being a multi elemental technique. Thus it is much faster, no pretreatments such as dissolution/digestion or activation were required. According
to our results, the EDXRF method could be applied to analyze different oil fly and boiler ash. However, since the water-soluble fraction of elements can be dissolved in the respiratory tract lining fluid causing oxidative stress. Hence, wet chemical analysis by ICP-MS would also be important due to its excellent detection limits, as well.