Determination of Trace Cadmium and Tin in Lead Alloys by Inductively Coupled Plasma-Mass Spectrometry

Due to the low concentrations of cadmium and tin in lead alloys and the single element analysis performed by using the national standard method, the analytical protocol is very complex and the detection limit is not ideal. In this paper, a new analytical method for determining trace cadmium and tin in lead alloys by Inductively Coupled Plasma-Mass Spectrometry is reported. In this method, lead alloys are digested by low-concentration of nitric acid. The low temperature and slow digestion process assures the complete dissolution of samples and reduces the mass spectrometry interferences from multiple ions. Lead matrix matching and the addition of tartrate assure the medium consistency of the standard and sample and avoid hydrolysis of the tin content. Using 103Rh as an internal standard and 111Cd and 118Sn as the measuring isotopes, the mass spectrometry interferences are reduced. The detection limits of Cd and Sn are 0.05 ng/g and 0.04 ng/g, respectively, which are much lower than those of the national standard method (1-6 μg/g). The precision of this method is 4.0%. This method needs a relatively small sample weight, which simplifies the analytical process and can determine trace elements in alloys precisely and accurately.