Chlorine neutron activation

The neutron activation analysis of the polymer reveals that initiation is effected predominantly by chlorine atoms. No retardation or inhibition were detected,... 

Several radiochemical studies have been reported, such as the analysis of phosphorus and chlorine by fast neutron activation and synthesis by radiochemical methods. ... 

The need for special facilities for work involving neutron activation analysis and radiochemical measurements has been referred to above in Section 4.3.6. Other safety factors may also influence your choice of method. For example, you may wish to avoid the use of methods which require toxic solvents, such as benzene and certain chlorinated hydrocarbons, or toxic reagents, such as potassium cyanide, if alternative procedures are available. Where Statutory Methods have to be used, there may be no alternative. In such cases, it is essential that staff are fully aware of the hazards involved and are properly supervised. Whatever method is used, the appropriate safety assessment must be carried out before the work is started. Procedures should be in place to ensure that the required safety protocols are followed and that everyone is aware of legislative requirements. 

Selected ion monitoring can be used for the determination of the relative amount of each component of a mixture, introduced into the mass spectrometer by the direct inlet probe However, such a determination requires reference mixtures of known composition for calibration. In the present experiment, since the monochloro pentaziridino derivative had not yet been isolated in the pure form, it was necessary to determine its concentration, by an auxiliary method, in a sample which could then be utilized as a reference mixture for further experiments. In order to do this we titrated chlorine in the toxic sample of MYKO 63 (B) by the classical method. The results indicated that the amount of N3P3AZJCI was between 0.5-1.5 %. The large statistical error is due to the low chlorine content in the sample examined. Thus, we used the remarkable possibilities provided by neutron activation analysis when the impurity to be quantified is a chlorinated moiety. It is well-known indeed that the C1 -f 2n peak is amongst the most easily detectable by neutron... 

In the first step, we were able to separate this penta derivative by preparative H.P.L.C. and we subsequently treated it with an excess of propyleneimine in order to reach the required hexasubstituted compound. Under such conditions, we succeeded in preparing a N3P3(MeAz)g real sample (free of chlorine, as demonstrated by neutron activation analysis) identified by mass spectrometry (Fig. 32) and by P nmr (Fig. 33) (6 = — 36 ppm with 85 % HjPO as standard, to be compared with 8(N3P3Azg) = --37 ppm). The refractive index of this sample, n = 1.4825, appeared to be significantly far from Ratz s value. 

The mass spectrum of SOAz is shown Fig. 38 and its pattern is quite different from that of MYKO 63 in fact we no longer observe the fall of the Az leaves which characterizes any mass spectrum within the MYKO 63 series. The base peak is at m/z 320 and there are very few other secondary peaks till m/z 50. No chlorinated impurity could be detected either by mass spectrometry or by neutron activation. 

To measure elemental chlorine present in a very weak concentration (of the order of a few ppm) in a sample of steel, by the method of neutron activation... 

As mentioned earlier, the starting materials are of high purity. Because we work in a closed system and because we have an electrodeless discharge there should be no sources of additional impurities. Neutron activation analysis revealed that all the transition metal impurities that strongly affect the transmission properties of the optical fibers are lower than 1 ppm. From fiber transmission measurements we know that, besides traces of OH, some impurities must be lower than 1 ppb because only the intrinsic attenuation of the material is found. The chlorine content is rather large at 0.1%, even at the deposition temperature of 1000 °C. Fortunately the chlorine does not affect the optical properties in the interesting region of 0.6 pm - 1.5 pm. 

NOTE All values are given as weight percent ( 95% confidence limit). Sulfate and chloride were analyzed by ion chromatography carbonate was analyzed by classical titration and calcium, magnesium, chlorine, aluminum, and sodium were analyzed by neutron activation analysis. 

Mass spectrometry of zinc Isotopes has been realized using either chelates on a solids probe(10,11,17) or thermal Ionization of purified solutions(12). Both of these approaches require a chemical separation of all of the metals and this separation must be accomplished In an environment free of contamination from the metal(s) of Interest In the part-per blllion range (19). Neutron activation also requires a set of separation steps. In this case the requirement for a contamination-free environment Is the same but the chemical separation Is mainly to remove sodium and chlorine (2). 

Supports and Catalysts. The catalyst supports used in this work are described in Table I. The surface areas, except for the sillcalite, were measured by the multi-point BET method. The surface area for the sillcalite was obtained from the manufacturer. Silicalite is an essentially aluminum-free pentasil zeolite (14) manufactured by Union Carbide. The chlorine contents of the supports were determined by neutron activation analysis, and sulfur contents were obtained with a Leco sulfur analyser. Sulfur and chlorine contents were measured since these elements may influence subsequent hydrogen adsorption on the supported platinum catalysts (15). 

Gether, J., G. Lunde, and E. Steinnes. 1979. Determination of the total amount of organically bound chlorine, bromine and iodine in environmental samples by instrumental neutron activation analysis. Anal. Chim. Acta 108 137-147. 

A reasonably complete analysis of the inorganic chemical composition of the aerosol requires much effort and involves, in addition to wet chemical methods, instrumental techniques such as neutron activation analysis, atomic absorption spectroscopy, or proton-induced X-ray emission (PIXE). These latter techniques yield the elemental composition. They furnish no direct information on the chemical compounds involved, although auxiliary data from mineralogy, chemical equilibria, etc. usually leave little doubt about the chemical form in which the elements occur. Thus, sulfur is present predominantly as sulfate, and chlorine and bromine as Cl- and Br-, respectively, whereas sodium potassium, magnesium, and calcium show up as... 

Another volatile radionuclide formed in HTGR fuel is 3.1 X 10 year Cl, formed by neutron activation of chlorine contaminant in the fuel, according to the reaction... 

Part-per-billion levels of molybdenum can be measured by neutron activation. After two or more hours irradiation at a neutron flux of 1012 n cm"2 sec 1, the principal gamma at 141 KeV [98Mo(n,y,p) 99mTc] is readily measured. In crude oils, however, some Bremsstrahlung interference may be encountered as a result of activated sulfur or chlorine. 

The analyses of the dust and salt components have been performed by various methods in our laboratory. Neutron activation analysis was used to determine Na, Mg, Al, Ti, V, Mn, Sc, Fe, Co, Sb, Ce, and Eu in dust (28). Fluoride in dust (and the K value in Table III) was done by photon activation analysis (12, 28). The salt portions of the aerosol and rainwater samples were analyzed for Na, K, Cl, and F. Sodium was determined by neutron activation and atomic absorption, potassium by atomic absorption, chlorine by titration, photon activation, and neutron activation, and fluoride by ion-specific electrode and photon activation (12, 28-30). Two analytical methods were used for Na, F, and Cl in the same samples to determine precision and accuracy. 

Using the method of short-term instrumental neutron activation analysis (INAA) (Vobecky et ai, 2000), we simultaneously determined the concentration of bromine, chlorine and sodium in the samples of mother s milk taken... 

Results of chlorine determined by instrumental neutron activation analysis for control and AD subjects are summarized in this table. Applying statistical treatment to the data sets, mean SD, confidence interval and significance (F-test, f-test) were calculated. Where a trend is indicated to be significant the p-value is <0.05. Mean values cannot be given, if we have only few data (parenthetic values) and therefore statistical treatment is not possible (-). n.s. There is no significant difference between the control and AD values. 

Fawkes, J., D.B. Walters and J.D. McKinney, Neutron Activation Analysis of Organically Bound Chlorine. Precautions... 

R.J. Norstrom, A.P. Gilman and D.J. Hallet, Total organically-bound chlorine and bromine in Lake Ontario Herring Gull eggs, 1977, by instrumental neutron activation and chromatographic methods, Sci. Total Environ. 20 217 (1981). 

It was proved that total chlorine, bromine, and iodine content of water samples can be determined with neutron activation analysis however, the high cost and less number of instruments available hinder the broad-scale application of that very sensitive technique in everyday water analysis [80-82]. 

That fallout of trace elements from atmospheric pollution is widespread and far from confined to urban and industrial areas, is also borne out by data published by the UK Atomic Energy Authority, who determined, by neutron activation analysis, about 30 trace elements in airborne dust, rainwater and dry deposition, sampled at regular intervals in north-west England [188]. The highest concentrations measured in air were for chlorine, sodium, calcium, aluminium, iron, lead and zinc, and there were also measurable levels of antimony, arsenic and mercury, usually in the winter months, when there was a general increase in trace-element concentration. Further data were published on the atmospheric content and total deposition of a wide range of trace elements at seven non-urban sites (one in Shetland) in the UK in the years 1972 and 1973 [189]. Data have also been published for the North Sea and the Firth of Clyde [190]. 

In 1980s, Rack and colleagues at University of Nebraska carried out a series study on speciation of iodine, chlorinated pesticides, and seleium in urine using liquid chromatography and molecular neutron activation analysis. They developed procedures for trace level determination of iodoamino acids and... 

In recent years some research has been undertaken on the development of other non-intrusive techniques for determining the contents and status of munitions. These include neutron activation analysis, ultrasonics and acoustic resonance techniques. Whilst primarily aimed at the Russian and U.S stockpiles, these techniques may nevertheless also have application in the old chemical weapons field. One technique in particular has been fielded and successfully used by U.S. EOD teams on a number of occasions over the last two years. This device, which is based on the use of photon-induced neutron spectroscopy (PINS), makes it possible to identify the presence or absence of the elements phosphorus, sulphur, chlorine, fluorine and arsenic within the munition. Clearly this information not only helps to identify the presence of a chemical fill, but in many circumstances also means it is possible to identify the fill. The development of more and improved techniques of non-destructive analysis will be a major factor in the development of safer techniques for the recovery and disposal of these old munitions. 

Neutron activation analysis can indicate the nature of the constituent elements. It enables the creation of a database and the sorting of projectiles as a function of elements contained (the presence or absence of arsenic, for example). It is now possible, using this technique, to identify chlorine or arsenic in less than two minutes. The neutrons may come from a natural source (such as Am-Be or Cf) or from a generator tube. In both cases, a mobile analyser is desirable. 

Neutron activation analysis (NAA) has been used for many years with stationary equipment for identification and determination of chemical elements. Of present interest is its use to determine the three characteristic elements chlorine, arsenic and bromine, which appear in arsenicals and some blister agents. Efforts are under way now to develop mobile equipment. 

To show a possible insertion of chlorine in the phorphyrin structure of Chi RC I and its possible position, NMR spectroscopy and neutron activation experiments were carried out. 

One of the basic requirements is to synthesize the desirable compounds and to rapidly transport them to the equipment for chemical experiments. The time spent to accomplish such processes and its probability distribution can be properly determined only when a radioisotope of the element under study can be produced in a quantity that can be easily and accurately measured. It has never been the case for the transactinoid elements. Rough estimation of the chlorination time of Zr and Mo was done in the model experiments described in the above Section (see also Fig. 1.2). The ampoule was filled with pure inert gas, then closed and bombarded for some time with neutrons at ambient temperature. Thus, the thermalized fission products were accumulated on the walls. Then the ampoule was heated and flushed for a short time with the gas containing a reagent. Most of the activity got transferred into the nap in 30 seconds or so it involved a mean gas hold-up time of 15 seconds, so that the actual upper limit of the chlorination time could be set as 15 seconds. 

Most biological matrices contain considerable amounts of sodium and chlorine which, after activation, emit gamma rays with great penetrating power 1368.6 and 2754.0 keV ( Na) or 1642.4 and 2167.5 keV ( CI). Thus, 1 mL of serum contains approximately 3.25 mg of sodium and 3.95 mg of chlorine. After irradiation for 5 h in a neutron flux of 4 10 n-cm -s the first gives rise to approximately 1 mCi or 37 MBq of Na (half-life 14.959 h), the second to approximately 0.75 mCi or 28 MBq of CI (half-life 37.21 min). Obviously. Na forms the most serious problem. 

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