Determination of rare earth elements in blood serum reference sample by chelating resin preconcentration and inductively coupled plasma mass spectrometry

Rare earth elements (REEs) in a blood serum reference sample, which is a freeze-dried sample issued from the National Institute for Environmental Studies, Japan, have been determined by inductively coupled plasma mass spectrometry (ICP-MX) after sample digestion and concentration pretreatment. The freeze-dried serum sample (ca. 0.8 g), which corresponded to 10 ml of original blood serum, was digested with HNO, with heating on a hot plate. The digested sample was then diluted with 100 ml of 0.1 M HNO3, and REEs in the diluted solution were adsorbed on chelating resin (Chelex(R) 100). The resin was then filtered with a glass filter. Finally, REEs on the resin mere dissolved with 10 ml of 2 M HNO3 aqueous solution, and the sample solution was analyzed by ICP-MS. The concentrations of all the REEs were successfully determined by the present method. The recovery values for REEs were in the range of 70-80%, and the relative standard deviation of the recovery values in repeated experiments (n = 3) was less than 5% for all REEs. In addition, 20 other elements were also determined by ICP-MX and ICP-AES.