Radionuclide detection limits

Samples Method Radionuclides Detection limits/lsotope ratios measured References... 

Samples Equipment Radionuclides Detection limits References... 

In cases where the induced radionuclides of trace elements are masked by matrix activity, radiochemical separation provides interference-free detection limits close to... 

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. 

According to the technology developer, geochemical fixation can treat dissolved hexavalent chromium and other metals in groundwater at concentrations ranging from the detection limit to several hundred parts per milhon. The developer asserts that geochemical attenuation can treat most of the common heavy metals, trace elements, and namral radionuclides that occur in groundwater, such as metal-cyanide complexes, arsenic, cadmium, chromium, copper, lead, selenium, uranium, and radium. 

At the end of four weeks of continued use, during which 4 liters of eluate were collected, samples were sterile and non-pyrogenic. Isotonicity was confirmed (NaCl = 8.94 .03 mg/ml) and neutrality maintained (pH = 6.27 0.16). No tin was detected in generator eluates by differential pulse polarography above a detection limit of 0.1 lig/ml. The radionuclidic identity of Rb-82 is easily confirmed by verification of its 76 sec half-life or through gamma spectrometry. 

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...

Henry et al.33 reported that improvements in quadrupole ICP-MS resulted in ag mass detection capability. Consequently the analysis of radionuclides with shorter half-lives is also possible. In Table 9.38 the detection limits of several mass spectrometric techniques for the determination of long-lived radionuclides are compared. 

Long-lived radionuclides occur at extremely low concentrations, especially in environmental samples, therefore several authors have proposed matrix separation and enrichment of the analytes before analysis.21,24,26,3 39 Radiochemical methods often require very careful and time consuming separation and enrichment processes and measurement procedures of a-, (3- and -emitting radioactive species at the trace and ultratrace level using conventional radioanalytical techniques 40-43 Trace/matrix separation, which is performed offline or online in order to avoid possible isobaric interferences, matrix effects and to reduce the detection limits for the determination of long-lived radionuclides, is also advantageous before ICP-MS measurements as the most widely applied mass spectrometric technique. 

Table 9.45 Detection limits of LA-ICP-MS for radionuclides in mosses deposited on stainless steel plates after chemical separation.

For cases where radionuclides were undetected, the detection limits are given in... 

Sensitivity. The detection limit for a number of radionuclides has been calculated using the GEM computer program (6). The calculations are based on a 1000-minute count of a zero-level sample. The... 

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