Proton activation analysis

Proton activation analysis (PAA) provides chemical composition of the materials at a depth of 300-500 pm under the irradiated surface. This technique has been used in the study of metallic objects such as ancient coins [27]. 

Self-diffusion was studied by using proton activation analysis to determine the concentration profiles of 1 0 in samples which had been exchanged with 1 0-emiched gas. For SiO2-20K2O-20wt%SrO, the diffusion data could be described by ... 

In addition to emission spectrometry with plasma excitation as described by Grallath et al. (8), which is claimed to be very precise even at the sub-A g/g level, activation analytical methods are well suited for this type of analysis. In the frame of a BCR round robin (Table IV-5) good agreement was obtained between instrumental proton activation analysis and deuteron activation analysis with radiochemical separation of Be or (31). These results indicate that interference from lithium in proton activation analysis is not significant in normal primary ingot aluminium. 

Proton activation analysis via the reaction B(p,a) Be is one of the most interesting methods as it is precise and accurate at + 5 %, provided Be is separated radiochemically before counting and the lithium concentration in the sample is very low, which is generally the case. The use of protons of lower energy (e.g. 2.75 MeV) theoretically allows the analysis to be carried out in an instrumental way, but experience proved that it is difficult to obtain a good precision. Deuteron activation analysis via the B(d,n) C reaction is an alternative. This method is free from nuclear interferences but requires a radiochemical separation of... 

All the techniques discussed here involve the atomic nucleus. Three use neutrons, generated either in nuclear reactors or very high energy proton ajccelerators (spallation sources), as the probe beam. They are Neutron Diffraction, Neutron Reflectivity, NR, and Neutron Activation Analysis, NAA. The fourth. Nuclear Reaction Analysis, NRA, uses charged particles from an ion accelerator to produce nuclear reactions. The nature and energy of the resulting products identify the atoms present. Since NRA is performed in RBS apparatus, it could have been included in Chapter 9. We include it here instead because nuclear reactions are involved. 

It has been reported that exchange of protons activated by enolization can be performed directly in a glass inlet system of the mass spectrometer prior to analysis by heating the sample at about 200° with deuterium oxide vapor for a few minutes. " Exchange has been observed with 2-, 3-, 6-, 11- and 17-keto steroids, but the resulting isotopic purity is usually poor,... 

The number of protons is unique to the element but most elements can exist with two or more different numbers of neutrons in their nucleus, giving rise to different isotopes of the same element. Some isotopes are stable, but some (numerically the majority) have nuclei which change spontaneously - that is, they are radioactive. Following the discovery of naturally radioactive isotopes around 1900 (see Section 10.3) it was soon found that many elements could be artificially induced to become radioactive by irradiating with neutrons (activation analysis). This observation led to the development of a precise and sensitive method for chemical analysis. 

There is room for further analysis in many traditional areas, as pointed out above during the discussion of enolization. Also, it is noted that the employment of transition state pKf values is very close to the use of the proton activating factors and deprotonating factors, introduced by Stewart (Stewart and Srinivasan, 1978 Stewart, 1985). It is to be hoped that the two approaches can be consolidated in a common view of acid-base catalysis. 

With analytical methods such as x-ray fluorescence (XRF), proton-induced x-ray emission (PIXE), and instrumental neutron activation analysis (INAA), many metals can be simultaneously analyzed without destroying the sample matrix. Of these, XRF and PEXE have good sensitivity and are frequently used to analyze nickel in environmental samples containing low levels of nickel such as rain, snow, and air (Hansson et al. 1988 Landsberger et al. 1983 Schroeder et al. 1987 Wiersema et al. 1984). The Texas Air Control Board, which uses XRF in its network of air monitors, reported a mean minimum detectable value of 6 ng nickel/m (Wiersema et al. 1984). A detection limit of 30 ng/L was obtained using PIXE with a nonselective preconcentration step (Hansson et al. 1988). In these techniques, the sample (e.g., air particulates collected on a filter) is irradiated with a source of x-ray photons or protons. The excited atoms emit their own characteristic energy spectrum, which is detected with an x-ray detector and multichannel analyzer. INAA and neutron activation analysis (NAA) with prior nickel separation and concentration have poor sensitivity and are rarely used (Schroeder et al. 1987 Stoeppler 1984). 

Landsberger S, Jervis RE, Kajrys G, et al. 1983. Characterization of trace elemental pollutants in urban snow using proton induced x-ray emission and instrumental neutron activation analysis. Int J Environ Anal Chem 16 95-130. 

Other frequently used methods for determining fluoride include ion and gas chromatography [150,204,205] and aluminium monofluoride (AIF) molecular absorption spectrometry [206,207]. Less frequently employed methods include enzymatic [208], catalytic [209], polarographic [210] and voltammetric methods [211], helium microwave-induced [212] or inductively coupled plasma atomic emission spectrometry [213], electrothermal atomic absorption spectrometry [214], inductively coupled plasma-mass spectrometry [215], radioactivation [216], proton-induced gamma emission [217], near-infrared spectroscopy [218] and neutron activation analysis [219]. 

Quantitative trace element analysis of diamond by LA-ICP-MS using different synthetic multielement carbon based standards (e.g., cellulose pellets) is discussed by Rege et al 2, whereby 13C was used for internal standardization. Concentrations of 41 elements were determined in two fibrous diamonds from Jwaneng Botswana (JWA 110 and 115) by relative sensitivity coefficients measured using the synthetic cellulose standard. The analytical data were verified by means of instrumental neutron activation analysis (INAA) and proton induced X-ray emission (PIXE).72... 

However, whereas this analysis of competition effects in anisole acetylation is very attractive, the following oversimplification which was made also has to be considered indeed, the competitive adsorption of the very polar acetic acid product, which inhibits arene acetylation[52,53] and the adsorption equilibrium constants were related to adsorption within the zeolite micropores only, without taking into consideration chemisorption over the protonic active sites. 

There are many examples of relatively straightforward use of ICP-MS for the analysis of biological fluids. Antimony has been measured in blood after a 14 1 dilution [236]. Cesium serum levels were found to be elevated in patients with alcohol dementia but not in Alzheimer s disease patients [237]. Cobalt levels in rat serum depended on the form of cobalt [238] ingested. Bismuth levels were measured in human blood and urine by using a direct injection nebulizer [239]. Lead was measured in the blood and blood plasma of smelter workers and the general population [240]. The measurement of trace elements in serum by ICP-MS has been compared to results from neutron activation analysis and proton-induced x-ray emission [241]. Semiquantitative analysis can also be used to obtain a rapid screening of samples [242]. 

Examples of thenoyltrifluoroacetone (TTA) (in benzene) extraction can be found in the separation of. 3.8-minute V 2 in. neutron activation analysis (90), of zirconium activities in niobium bombarded by protons (128), and of 1.8-minute Pa22 from the reaction products of thorium bombarded.by a cyclotron (172,173,175)- 16-second Y89"1 (109) and 25-minute Am246 (74), the daughter products of Zr and Pu2 respectively, were separated by back extraction into acidic aqueous solution from the parent in TTA-benzene solution. 

Ion Chromatography Plasma Spectroscopy Neutron Activation Analysis Proton-Induced Xray Emission... 

Thermal neutrons in the reactor are efficient in producing ( , y) neutron capture reactions e.g. Fe (n, y) f< Fe. The products of these reactions will have an excess of neutrons and generally decay by (/ ", y) emission. The major disadvantage is that the radioactive atoms will always be diluted with many -non-radioactive atoms and chemical separation is not possible, (n, y) reactions are however usefully exploited in neutron activation analysis (p. 471). With fast neutrons, proton, deuteron or alpha particle bombardment a change in atomic number accompanies the.reaction and chemical separation of the carrier free radiotracer becomes possible,... 

Dalton TP, Li Q, Bittel D, Liang L, Andrews GK (1996) Oxidative stress activates metal-responsive transcription factor-1 binding activity. Occupancy in vivo of metal response elements in the metallothionein-I gene promoter. J Biol Chem 271 26233-26241 Danscher G, Howell G, Perez-Clausell J, Hertel N (1985) The dithizone, Timm s sulphide silver and the selenium methods demonstrate a chelatable pool of zinc in CNS. A proton activation (PIXE) analysis of carbon tetrachloride extracts from rat brains and spinal cords intravitally treated with dithizone. Histochemistry 83 419 22 Danscher G, Jensen KB, Frederickson CJ, Kemp K, Andreasen A, Juhl S, Stoltenberg M, Ravid R (1997) Increased amount of zinc in the hippocampus and amygdala of Alzheimer s diseased brains a proton-induced X-ray emission spectroscopic analysis of cryostat sections from autopsy material. J Neurosci Methods 76 53-59... 

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