This rapid, nondestructive method is for determining nickel, iron and vanadium in distillate and residual oils and nickel, iron, vanadium and sulfur in solid pitches by energy dispersive x-ray fluorescence (XRF). The lower limit of detection for nickel, iron and vanadium is 2 mass-ppm. The lower limit of detection for sulfur in pitches is 100 mass-ppm.
The method assumes a linear relationship of percent metal vs. intensity when the concentration of the metal in the standards closely brackets the unknown. It also assumes that corrections for matrix absorption or inter-element effects are not required when properly calibrated standards of similar composition are used. Samples which are not homogeneous or that contain particulate material that precipitates on standing are not applicable.
The method is written for use with Kevex Model 0700-7000 Energy Dispersive instrument, however, other equivalent equipment is satisfactory.