Direct Determination of Iron Content in Used Greases by X-ray Fluorescence Method

Abstract

Direct determination of iron content in used greases by X-ray fluorescence method has been investigated. The following conclusions were obtained from the experimental results.(1) Standard samples were prepared by adding Fe-naphthenate or Fe2O3 to Li-grease and Na-grease to give 0.003∼1.5wt% iron content.Colorimetric analysis values of iron content in these standard samples were used as standard values and a linear calibration curve was obtained in the X-ray fluorescence analysis. Standard deviation of X-ray fluorescence analytical method was 2.6% at lower range of iron concentrations and 0.7% at higher range of iron concentrations. And also, standard deviation of the difference of colorimetric and X-ray results was 3.0% at lower iron concentration range and 0.9% at higher iron concentration range.(2) The X-ray fluorescence analytical results of iron content in various grease samples which were used in field test of motor cars checked well with the results of colorimetric analysis.(3) As this procedure is a direct method of determination of iron content in greases without ashing treatment, it is considered that this method is simple, rapid (15∼20 minute/one sample) and very useful for routine analysis.