THE APPLICATION OF DIOCTYL SULPHIDE IN THE ANALYSIS OF NOBLE METAL ELEMENT Ⅰ.DETERMINATION OF TRACE SILVER IN GEOLO-GICAL SAMPLE BY NAA

The extraction property of dioctyl sulphide has been studied for fhe NAA of trace silver in geological sample. The geological sample is irradiated in HWRR-2 reactor (neutron flux is (4-7)×1013n/cm2·s) for 200 hours. After cooling for more than a month, the irradiated sample is decomposed by mixed acid(HF -HNO3-HC104) , and the residue is dissolved in 1 N HNO3.The silver is extracted by 0.2 M dioctyl sulphide chloroform solution and the characteristic γ-ray of 110mAg is determined by Ge(Li) γ-spectrometry. The content of silver in the sample is determined by the comparator method The chemical yield of 110mAg for the complete procedure is 92%. Standard samples of sludge, rock and soil have been analyzed. The content of silver is in the range of 0.023-4.35 PPm. The precision of the method is±15%.