Arsenic INAA

Lin, X. and Henkelmann, R. (2003) Contents of arsenic, mercury and other trace elements in Napoleon s hair determined by INAA using the ko-method. The Journal of Radioanalytical and Nuclear Chemistry, 257(3), 615-20. 

When INAA is used and the concentration of Na in the sample is above 1%, the Na y-rays mask other useful y-ray peaks. In particular, arsenic and zinc abundances are not as easily determined in the shales as they are in coal by INAA (28). The oil and water appear to present no leakage problems at fluxes of 2 X 10 n cm" sec" for irradiation periods of 2 hr. These liquids were irradiated in sealed polyethylene vials inside of sealed polyethylene bags. The neutron activation analyses were performed at the U.S. Geological Survey in Denver, Golorado. 

X-ray fluorescence spectrometry (XRF) and instrumental neutron activation analysis (INAA) are commonly used for multi-element analysis of rock, soil, and sediment samples since they do not require chemical dissolution. However, the detection limit for arsenic using XRF is on the order of 5 mg kg and is too high for many environmental purposes. Once dissolved, arsenic can be determined using many of the methods described above... 

The Trace Metals Project conducted a study to identify the type of container which would provide minimum losses of arsenic and mercury by precipitation, volatilization, adsorption, or diffusion. Solutions of organomercury and organoarsenic compounds added to petroleum feedstock were used. Because of the relative ease with which mercury and arsenic can be determined at sub-parts-per-million levels in a hydrocarbon matrix by instrumental neutron activation analysis (INAA), this technique was used for the analytical measurements. The solutions were stored in five different types of glass and/or plastic containers and sampled periodically over eight months (12). The results of the study are summarized in Tables 2.III and 2.IV. 

The arsenic data obtained by PIXE and INAA present quite dififerent patterns. Whenever a large concentration of lead is present in the samples arsenic spectra peaks obtained by PIXE can be interfered, and also if arsenic is present in large quantities lead data can be also interfered. Comparing Fig. 2 with Fig. 5 we observe that in the south of the country around Lisbon the Pb-As pattern is quite similar. In the other hand Fig. 5 presents large concentrations of Pb in the north of the country which is there quite similar to the As pattern given by INAA. Therefore we are taken to conclude that the As-pattern given by PIXE should not be selected for this kind of samples. The ditference between the two techniques shown in Table 3 is now explained. Therefore INAA data should be selected. 

Figure 3 Instrumental methods for the determination of arsenic compounds (Abbreviations AAS, atomic absorption spectrometry APS, atomic fluorescence spectrometry CE, capillary electrophoresis GC, gas chromatography HG, hydride generation ICP-AES, inductively coupled plasma-atomic emission spectrometry ICP-MS, inductively coupled plasma-mass spectrometry INAA, instrumental neutron activation analysis LC, liquid chromatography MS, mass spectrometry).

The experiments were conducted using trace elements solution containing different concentrations. Each treatment was replicated three times. The rhizome and frond were analyzed for inorganic arsenic. Total arsenic contents in soil and plant were determined by instrumental neutron activation analyses (INAA), Nuclear Reactor lEA-Rlm. The sample irradiation was carried out at the nuclear reactor for 8 h and under thermal neutron flux of 2.7 X 10 ncm s subsequently, a decay time of 3 days and 3 h counting time were employed. The radionuclide activities were measured using a gamma-ray spectrometer comprising a hyper-pure GE detector and associated electronic system. The spectra of the samples were measured under the same experimental conditions of the standard photopeak of 657 keV of As. The amount of anion absorbed was calculated as the difference between the anion concentration before and after reaction with the sod-plant systems. 

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