Determination of Trace Aluminum in Urine by Neutron Activation Analysis

Trace aluminum determination in biological material is difficult because of the very low levels generally present and the fact that significant quantities of aluminum are present in all reagents and the laboratory environment. A cation-exchange chromatography procedure is outlined for the simple and quantitative determination of trace amounts of aluminum (i.e., ≥0.05 μg Al/ml urine) in biological material, employing ²⁸Al neutron activation analysis. The procedure, utilizing a lowpower nuclear reactor (~3.1 × 10¹¹n/cm²-s), consists of a) wet digestion of the biological material, b) cation-exchange chromatography employing 1 M nitric acid to remove the major radiocontaminants sodium, chloride, silicate, and phosphate ions, and c) irradiation and radioassay of the aluminum contained in the resin. The aluminum concentration in normal urine samples varied from <0.05 to 0.13 μg Al/ml. The precision of this method is such that we can measure with confidence aluminum levels of 0.05 μg/ml or above.