Beryllium characterization in soils by selective extraction

In the present work, an analytical method has been developed for the determination of the amount of man-made beryllium metal and/or beryllium compounds in soil in addition to the amount of native beryllium that is present. The method is based on the premise that if high-fired beryllium oxide can be extracted efficiently, then beryllium metal and acid-soluble beryllium salts would also be extracted efficiently. The proposed method involves the addition of 9 mL of an aqueous solution of 5% (wt/vol) ammonium bifluoride (ABF) to a 10-mL tube with 250 mg of dried, sieved soil. The tube is placed in a convection oven at 70 ᵒC and is mechanically rocked for 60 min to mix the sample while it is being heated. Beryllium oxide, beryllium metal and beryllium salts would include virtually all of the anthropogenic (man-made) beryllium compounds that might contaminate soil. Compounds that may be naturally present in soil, such as beryllium silicates and beryllium aluminosilicates, are not extracted efficiently by ABF solution under these conditions. As a second step after the initial extraction of the sample of soil with ABF solution, the soil is completely dissolved in a mixture of strong acids and that acid solution is then analyzed to determine the residual beryllium. The ratio of the extractable to residual beryllium in the same aliquot of native soil can be measured for a soil type in a local region and then used to calculate the amount of anthropogenic beryllium in soil. Therefore, the method may have application in the measurement of beryllium-contaminated soil at sites where beryllium oxide, beryllium metal and/or beryllium salts may have been used.