PRECISE DETERMINATION OF NGG-1 LEVELS OF ANTIMONY IN HIGH-PURITY COPPER BY ISOTOPE-DILUTION - ICP-MS

Isotope dilution/inductively coupled plasma mass spectrometry (ID/ICPMS) was applied to the determination of ng g-1 levels of antimony in high purity copper. Mass discrimination effects of two main components, copper as a matrix and lanthanum for coprecipitation, on the measurement of isotope ratio (Sb-123/Sb-121) were not significant. It was found that there is isobaric interference of Te-123 in the measurement of the isotope ratio. But this effect could be corrected by subtracting the spectral intensity of Te-123 from that of m/z = 123; the intensity of Te-123 can be obtained by measuring the intensity of Te-125 and the relative intensity of Te-123 and Te-125. The analytical results for NIST SRMs obtained by ID/ICPMS agreed well with the certified values. After concentrating antimony by the coprecipitation method, ID/ICPMS can determine 4.4 ng g-1 of antimony in copper sample with 10% RSD.