ICP-AES Determination of Trace Amount of Metal Elements in Crude Oil with Microwave Assisted Ashing of Sample

Five grams of sample of crude oil was ignited for 1 h in microwave assisted ashing furnace at 800 ℃, and the residue was dissolved with HCl (1+1) solution and evaporated to near dryness. After taking up with water, the solution was diluted to 50 mL in a volumetric flask and used for ICP-AES determination of the trace metal elements, including Fe, Na, Ni, V and Ca. The proposed method was applied to the analysis of crude oil, the analytical results obtained by microwave ashing were compared with those by conventional ashing, and as verified by t-test at the confidence level of α=0.05, no significant difference was found between the two ashing methods. Values of recovery found by standard addition method were in the range of 92.0%-108.4%, with RSD′s (n=6) in the range of 2.2%-6.5%.