Charles T. Kenner

Ion Exchange Separations and Atomic Absorption Determination of Trace Metals in Ores after Basic Fusion

The determination of trace constituents in ores by atomic absorption after basic fusion and solution in strong acid is erratic due to the light scattering and aspirator clogging of the high concentration of sodium salts. The sodium is separated from the trace constituents using a column procedure and an iminodiacetate chelating ion exchange resin which will retain di- and trivalent metal ions at pH values above 6.0 but will not retain alkali metal ions. The trace constituents are determined by atomic absorption after elution with HCl. The precision (standard deviation of the mean) of the atomic absorption method is increased at least fivefold by the resin separation and the method is applicable to concentrations in the low ppm range. The standard deviation of the mean for an NBS sample containing 0.007% Cu is 0.0004%.

Determination of Antimony, Tin, and Arsenic in High Antimonial Lead Alloys by Vacuum X-ray Fluorescence

A method of x-ray fluorescence analysis for high antimonial lead alloys has been developed to cover antimony concentrations between 6 and 18%, a range not covered in previously published x-ray methods. The proposed method utilizes a General Electric XRD 6 VS spectrometer, chill-cast mold, and a special cutting bit to produce a smooth surface. Ten separate 10-sec counts are taken at 120° intervals to offset nonhomogeneity of the surface. Average counts vs concentration are plotted to obtain calibration curves and percentage concentration. The precision and accuracy of the proposed method compare favorably with the classical wet method. The average standard deviation of the proposed method in terms of the amount present is 1.19% for antimony, 2.03% for tin, and 2.37% for arsenic. These values are within the limits required in the specifications of most high antimonial lead alloys. A time saving of 2 h per sample is realized by the x-ray method over the classical wet method.