Determination of trace elements in high purity iron by solid phase extraction using bonded silica/ICP-MS

We attempted a simple pretreating method consisting of solid phase extraction using bonded silica with benzenesulfonic acid (SCX) as the solid phase sorbent to determine trace elements in pure iron samples by means of inductively coupled plasma mass spectrometry (ICP-MS). The isotope dilution method was used along with the method mentioned above to ensure precise determination of Zn. We dissolved the sample of 1.00 g by nitric acid, subsequently adding citric acid as masking agent. The analytes could be separated by 1-10 phenanthroline as chelate from the matrix by solid phase extraction after adjusting the pH and adding 1-10 phenanthroline. The optimum condition for iron separation was 0.01 kmol(.)m(-3) 1-10 phenanthroline, 10 cm(3); citric acid (10 w/v%), 10 cm(3); pH, 5.5; SCX, 0.5 g as the solid phase sorbent; and nitric acid, 2 cm(3) as eluate. In this method, some trace elements such as Ni, Cu, Cd and Zn were determined by ICP-MS using the eluate. The limits of detection in ng/g were Ni 0.29, Cu 0.10, Cd 0.20 and Zn 0.15. We precisely determined the Zn content by jointly using the isotope dilution method.