A rapid method has been developed for the determination of vanadium and nickel in crude oils in concentrations above 5 ppm. Duplicate analyses for both nickel and vanadium require only one hour, and excellent precision is obtained. At a concentration level of 100 ppm of vanadium, the standard deviation is 3.1 ppm, and at a level of 30 ppm of nickel, the standard deviation is 1.6. The results are comparable to those obtained by spectrophotometric and optical emission spectrographic analysis.

Conversion of the crude oils to greases by the addition of aluminum stéarate minimizes the usual difficulties of handling liquid samples in the conventional-geometry fluorescent X-ray spectrometer. Scattered tungsten emission lines from theX-ray tube serve as internal standards to correct for instrumental and matrix variations.

A new sample tray that permits the insertion of four samples into the instrument at a time has been constructed. Each sample can be moved into position for analysis without opening the sample chamber, making it necessary to waitfor the helium to sweep the trapped air from the X-ray path only once for each four samples.