1984 Volume 33 Issue 9 Pages T95-T98
Strontium in silicate rocks was determined by the following procedure. A rock powder sample prepared to pass through a 100-mesh size sieve (0.10.5 g) was taken in a Teflon beaker, and 6 ml of 46 % hydrofluoric acid and 1 ml of 70 % perchloric acid were added. After being allowed to stand for over one day, the mixture in the beaker was concentrated by heating on a hot plate until white fumes of the perchloric acid appeared. The content in the beaker was transferred to a glass beaker with 2 ml of 61 % nitric acid and 0.5 ml of the perchloric acid, and concentrated until white fumes appeared. Further, 2 ml of 20 % hydrochloric acid was added and warmed. After cooling, the rock solution was made up to 100 ml with water. To a 50-ml stoppered centrifugal tube, a 10-ml portion of the rock solution was transferred, and 1 ml of 2 % 8-quinolinol solution was added. Then the solution was adjusted to pH 5 with both saturated sodium acetate solution and hydrochloric acid, and made up to 15 ml. The decomposed rock sample solution with 20 ml of chloroform was shaken for 5 min. The decomposed rock sample solution was shaken with 20 ml of chloroform for 5 min, and then centrifuged at 2500 rpm for 5 min to separate an aqueous phase from an organic one. After adding 1 ml of 2 % lanthanum solution into a 10 ml portion of the aqueous phase, strontium was determined by atomic absorption spectrometry at 460.7 nm. This method was applied to the rock reference materials, JB-1 and JG-1, issued from the Geological Survey of Japan. Analytical values of strontium in the rocks were almost consistent with their certified and recommended values.
