ICP-AES Detemination of 12 Metal Elements in Used Lubrication Oil

The used lubrication oil sample was burned in a 100 mL porcelain crucible and then ignited at 600 ℃ for about 3 h.The residue was dissolved in HCl(1+1) and the solution was evaporated to ca.1-2 mL,and diluted to 25 mL in a volumetric flask with 0.1 mol·L-1 HCl,which was used for ICP-AES analysis for its contents of Zn,Al,Fe,Co,Pb,Cd,Mn,Mg,Cu,Ca,Ba and Na.In order to lower the salt effect and to eliminate deviation due to long period of time in wavelength scanning,3 mixed standard solutions containing the 12 metal ions separated in 3 groups.The metal elements having their values of wavelength close to each other were classified into one group and the elements with high contents were distributed into the 3 groups.Sample analysis for the 12 elements was also performed in 3 groups as the mixed standard solutions.Under the specified instrumental conditions,and using the selected analytical spectral lines,no interference was observed among the co-existing elements.Precision of the method was tested,and values of RSD′s (n=6) obtained were in the range of 1.19%-10.50%,and test for recovery by standard addition was performed and results obtained were in the range of 92.4%-107.4%.