SIMULTANEOUS DETERMINATION OF TRACE AMOUN TS OF BISMUTH AND ANTIMONY IN HIGH-PURITY TIN BY INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY

The separation and determination of trace amounts of Bi and Sb in high -purity Sn were studied. After the sample was dissolved with mixture o f phosphoric acid and sulfuric acid, Bi and Sb were separated from Sn by extracting into xylene with diethylammonium diethyldithiocarbamate (DDDC) and subsequently back-extracted into nitric acid for the determ ination by ICP-AES. Sn are little extracted from phosphoric acid solut ion, so it is possible to separate Bi and Sb from Sn. The apparent dis tribution ratios (D) of Bi, Sb and Sn between 5 x 10(-2) mol/l DDDC-xy lene and 4 mol/l phosphoric acid-0.5 mol/l sulfuric acid were found to be 1.7 x 10(3) for Bi, 2.5 x 10(3) for Sb and 5.5 x 10(-3) for Sn. Th erefore, the separation factors (S=D-m/D-sn.) of Bi and Sb from Sn are calculated to be 10(5) level, respectively. The recoveries of Bi and Sb were satisfactory throughout the extraction with 5 x 10(-2) mol/l D DDC in xylene from 4 mol/l phosphoric acid-0.5 mol/l sulfuric acid sol ution and the back-extraction with 60% nitric acid. Y was used as an i nternal standard for ICP-AES measurements. The diverse elements which are contained in Sn caused no interference for the determination of Bi and Sb. The detection limits were found to be 41 ng/g for Bi and 84 n g/g for Sb using Ig of Sn sample. The proposed method was applied to a nalysis of the real samples and a reference material with good results .