IP 407: Determination of barium, calcium, phosphorus, sulfur and zinc by wavelength dispersive X-ray fluorescence spectroscopy

Overview:

Scope

This standard specifies a method to determine barium, calcium, phosphorus and zinc content of unused lubricating oils at element concentration ranges of 0,03% (m/m) to 1,0% (m/m) and sulfur content in the range 0,1% (m/m) to 2,0% (m/m). The range can be extended to higher concentrations by dilution of the sample. Additives can also be determined after dilution.

NOTE 1 The additive elements found in lubricating oils will affect the measured intensities from the elements of interest to a varying degree. In general for lubricating oils, the X-radiation emitted by the element of interest is absorbed by the other elements in the sample matrix. Also, the X-radiation emitted from one element can further excite another element. These effects are significant at concentrations varying from 0,03% (m/m) due to the heavier elements, to 1 % (m/m) for the lighter elements.

NOTE 2 The measured intensity for a given element can be mathematically corrected for the absorption of the emitted radiation by the other elements present in the sample. Suitable internal standards can also compensate for X-ray inter-element effects.

NOTE 3 If an element is present at significant concentrations and an inter-element correction for that element is not employed, the results can be low due to absorption or high due to enhancement.