Long-lived radionuclides mass spectrometry detection limits

ICP-MS (inductively coupled plasma mass spectrometry) is frequently used for determining ultratrace amounts of technetium [9]. In spite of the high cost of the equipment, this detection method is far superior to other radiometric methods as regards sensitivity. When a double focussing high-resolution system is used (HR-ICP-MS) and an ultrasonic nebulizer is introduced [10], the detection limit is in the order 0.002 mBq. The ICP-MS method has been successfully applied to the determination of environmental "Tc as well as to other long-lived radionuclides of neptunium and plutonium in the environment. 

Conventional radiochemical methods for the determination of long-lived radionuclides at low concentration levels require a careful chemical separation of the analyte, e.g., by liquid-liquid, solid phase extraction or ion chromatography. The chemical separation of the interferents from the long-lived radionuclide at the ultratrace level and its enrichment in order to achieve low detection limits is often very time consuming. Inorganic mass spectrometry is especially advantageous in comparison to radioanalytical techniques for the characterization of radionuclides with long half-lives (> 104 a) at the ultratrace level and very low radioactive environmental or waste samples. 

Table 9.38 Detection limits of mass spectrometry for determination of long-lived radionuclides.2...

During the last decades methods such as Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), Inductively Coupled Plasma Mass Spectroscopy (ICP-MS), and Resonance Ionization Mass spectrometry (RIMS) have decreased the need for selective radiochemical procedures. Many long-lived radionuclides today have lower detection limits if using, e.g., ICP-MS than if performing radiometric measurements with reasonable measuring times. At present, the half-life limit is a few hundred years, i.e., nuclides with longer half-hfe (e.g., Tc, Np, or Pu) should preferably be measured by ICP-MS and more short-... 

Basically, the I content in the purified iodine fraction can be measured by different techniques. Due to the low specific activity of this long-lived radionuclide, direct 3 , y and X-ray measurement techniques show only a moderate detection capability better detection limits can be obtained by determination of the I mass present in the sample. Here, laser-induced fluorescence spectrometry offers in principle favorable results however, when this technique is applied, the difficulties associated with the preparation of the h chemical species at very low iodine concentrations have to be taken into consideration. The most sensitive I determination technique is neutron activation analysis, which leads to the formation of the... 

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