Determination of iodine-129 in vegetable samples by inductively coupled plasma mass spectrometry
Abstract
Work has been carried out at the Harwell Laboratory to develop an inductively coupled plasma mass spectrometry (ICP-MS) method capable of measuring 129I at contaminated environmental levels in vegetable samples. The inherent sensitivity of ICP-MS using conventional pneumatic nebulization is insufficient for this task, so that preconcentration and/or improved efficiency of sample introduction are required. The development of a method for introducing 129I into the ICP mass spectrometer in the form of I2 is described. The volatility of this species is used to overcome the low transport efficiency of pneumatic nebulization for the introduction of analytes in aqueous solution. Sample preparation and results for spiked vegetable material are discussed. Based on field blanks, a limit of detection of 0.2 ng, equivalent to approximately 1.4 ng kg–1(0.009 Bq kg–1) fresh mass of vegetable, is reported. A method precision of 12% relative standard deviation at 2.7 ng cm–3 has been achieved.