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Nanogram amounts of chromium can be extracted as oxinate into chloform. By treatment of the chloroform layer 3 M hydrochloric acid, oxinates of other elements and excess of reagent are removed, leaving a chloroform solution of the chromium chelate only. This solution is concentrated and transferred to the top of a small brass rod acting as sample holder. The intensity of the X-ray fluorescence of the Cr Kα line is measured with curved crystal optics. Chromium amounts greater than 5 ng can be detected. The application of the procedure to the analysis of the chromium content of urine is demonstrated.

An examination of the atomic absorption spectroscopy of calcium and magnesium has been made and the results confirm that several anions and cations interfere. Simple and reliable means are suggested for overcoming these interferences. The possibility of the use of a 2% isopropanol medium for overcoming several interferences on magnesium is also presented.