Precise determination of ng g^-1 levels of antimony in high purity copper by isotope dilution/ICP-MS

Abstract

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(¹²³Sb/¹²¹Sb) were not significant.It was found that there is isobaric interference of ¹²³Te in the measurement of the isotope ratio. But this effect could be corrected by subtracting the spectral intensity of ¹²³Te from that of m/z=123; the intensity of ¹²³Te can be obtained by measuring the intensity of ¹²⁵Te and the relative intensity of ¹²³Te and ¹²⁵Te. 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.