Multielemental hair composition of Brazilian Indian populational groups by instrumental neutron activation analysis

In the present paper, for the first time the multielemental compositionof hair samples of Indian populations living in the Xingu Park Reservation,in the Brazilian Amazonic region has been determined, by INAA. Irradiationswere carried out at the Interfaculty Reactor Institute (Delft, The Netherlands)and, using a combination of different irradiation and decay times, about 40elements could be determined in the hair. Previous analysis made at the RadiochemistryDivision of IPEN/CNEN-SP (Brazilian Nuclear Energy Commission) of hair samplesof a Brazilian control population allowed the determination of 20 elements,also by INAA. Comparison of the data obtained for the Indian populations andthe controls showed very significant differences in elemental compositionsfor some elements, like Hg, Mn and Al while for others, like Cu and Zn, theconcentrations were similar. A discussion of the differences found for otherelements also is made in the present paper.     

Determination of uranium in human head hair of a Brazilian populational group by epithermal neutron activation analysis

Hair analysis is extensively used in forensic sciences, assessment of occupational or environmental exposure and in some cases also for clinical and nutritional studies. Hair has a series of advantages in relation to other biomonitors, like blood and urine, since it is very easy to collect, very stable at room temperature and it represents not only instantaneous concentrations, but it can reveal the exposure along a given period of time. The assessment of environmental or occupational exposure to uranium is generally done by means of urine analysis, although a few papers have described attempts to use hair as a biomonitor. In the present work, epithermal neutron activation analysis has been used to establish base-line concentrations for a Brazilian populational group, living in Sao Paulo and not exposed to uranium, either environmentally or occupationally. For quality control, the reference materials Pine Needles NIST 1575 and Basalt USGS BCR-1 were used. The concentrations obtained for the control population studied up to now varied from about 2 to 50 ng·g⁻¹.     

Determination of mercury and methylmercury in hair samples by neutron activation

Mercury and methylmercury in hair samples were determined by neutron activation analysis. Samples were digested in 10M NaOH, and methylmercury was then isolated by solvent extraction with toluene. The isolated methylmercury was then absorbed onto cysteine paper. The dried cysteine paper was activated for six hours in a TRIGA reactor and methylmercury was analysed via 279.2 keV of²⁰³Hg. Methylmercury and total mercury in some standard reference materials were also analysed, and the results were in good agreement with those reported in the literature. Results for hair samples showed that the methylmercury concentration ranged 14–40% of the total mercury. Gas chromatogram showed that methylmercury was only present in the samples analysed. In samples where methylmercury and other organic mercury are presented, the NAA method is good for the determination of the total organic mercury only.     

Determination of mercury in air by neutron activation analysis

A sensitive method for the determination of mercury in sea and surface waters is presented. A distinction is made between inorganic, organic and particulate mercury. In the determination of inorganic mercury, the element is isolated by reduction and volatilization, followed by absorption on a charcoal column. The total mercury content of the water with and without suspended solids is determined by absorption from the solution onto a column of charcoal. In all cases, the mercury on the absorber is determined by thermal neutron activation analysis. The limit of detection is l ng 1^-1.     

Determination of mercury in bismuth by neutron activation analysis

A method has been developed for the determination of traces of mercury in bismuth by neutron activation analysis. After sample irradiation at a flux of 7 · 10¹³ n cm^-2 s^-1 for 20 min, mercury was separated from bismuth by addition of ammonium sulfide and re-dissolution of bismuth (matrix) sulfide with nitric acid, and filtration of sulfur containing mercury on a membrane filter. The activity of the 68- or 68–77-keV region, counted with a Ge(Li) or NaI(Tl) detector, was used for quantitative measurements. The method was applied to bismuth samples containing 0.1–100 p.p.m. of mercury.     

Determination of molybdenum in hair and wool by neutron activation analysis

Neutron activation analysis was applied to the determination of molybdenum in hair and wool. Ashed samples of hair and wool were irradiated for 15 min at a flux of 5·10¹³ n/cm²/sec to produce ¹⁰¹Mo. An acid solution of the ash was first boiled in the presence of sodium bromide and bromate to volatilize bromine (⁸⁰Br and ⁸²Br radioisotopes interfere) and then extracted with 0.1% α-benzoinoxime in chloroform to remove ¹⁰¹Mo from other interfering radionuclides. The ¹⁰¹Tc daughter from ¹⁰¹Mo was measured over the 0.31-MeV γ-ray photopeak after allowing the separated ¹⁰¹Mo to decay for 15 min. The molybdenum concentration in hair varied from 0.02 to 0.13μg/g while wool was found to contain 0.04–0.58 μg/g.     

Determination of trace elements in Brazilian cigarette tobacco by neutron activation analysis

The determination of 14 trace elements /Ba, Ce, Co, Eu, Fe, Hf, La, Nd, Rb, Sb, Sc, Sm, Tb and Th/ has been carried out in three different brands of Brazilian cigarettes. The samples and standards were irradiated for 8 h at a thermal neutron flux of approx. 5×10¹² n cm^–2s^–1. After the irradiation, the -rays activity was measured on a Ge/Li/ detector coupled with a 4096-channel pulse height analyzer. The results were compared with those obtained for the tobacco from American, Iranian, Turkish, Pakistan and Yugoslavian cigarettes. The amount of each element transferred to the ashes was determined.     

Determination of antimony in nail and hair by thermal neutron activation analysis

The concentration of antimony in nail and hair was determined by thermal neutron activation analysis. Samples were collected from the workers of an antimony refinery, inhabitants near the refinery, and residents in control area. They were irradiated by Kyoto University 5 000 kW Reactor for 1 h, and cooled for 30 to 100 days. After cooling, the concentration of Sb in nail and hair was estimated by measuring the intensity of gamma-ray from 124Sb of the samples, then the samples were washed by 0.1% aqueous solution of nonionic surface active agent in an ultrasonic cleaner. The gamma-ray spectrometry was done again (after washing). The concentration of Sb in nail before washing was 730 ppm for the workers, 2.46 ppm for habitants near the refinery, and 0.19 ppm for the control; after washing, it became 230 ppm for the workers, 0.63 ppm for habitants, and 0.09 ppm for the control. The concentration of Sb in hair before and after washing was 222 ppm and 196 ppm for the workers, and 0.21 ppm and 0.15 ppm for the control, respectively.     

Determination of mercury and arsenic in fresh water by neutron activation analysis

Neutron activation analysis has been applied for the determination of Hg and As in freshwater samples. Preconcentration of Hg and As from the samples before irradiation by using active carbon for scavenging the chelate complex of Hg with dithizone at pH 1 and Fe(OH)₃ for co-precipitating arsenic was used. After irridiation, mercury was determined by direct counting of the irradiated active carbon. Arsenic was separated from Fe(OH)₃ by precipitating arsenic in the metal form after removing¹²²Sb by extraction in 2N HCl with Ni-diethyldithiophosphoric acid in carbon tetrachloride. The method is simple and reliable.     

Determination of total mercury and methylmercury in hair samples from residents of Kuala Lumpur, Malaysia by neutron activation analysis

to estimate the level of total mercury and methylmercury in Kuala Lumpur residents, 400 hair samples were analysed by neutron activation analysis. Separation of methylmercury from hair samples were carried out prior to neutron activation. The average level of total mercury and methylmercury in hair samples were 3.38 mg^.kg^-1 (in range of 0.59-18.73 mg^.kg^-1) and 1.13 mg^.kg^-1 (in range of 0-4.65 mg^.kg^-1), respectively. The average percentage ratio of methylmercury to total mercury was 31.15% (in range of 0 to 75.81%). This revised version was published online in August 2006 with corrections to the Cover Date.     

Low level mercury analysis by neutron activation analysis

During the years 1974–77 about 200 low level mercury analyses on samples with less than 1000 ng Hg/kg were made at the Danish Isotope Centre. This paper describes our method of neutron activation analysis for low level mercury analysis. The accuracy of the mercury analyses is shown by the results of the determinations on NBS standard, SRM 1642, and on intercalibration analyses. The accuracy found is better than 10% for samples with about 100–300 ng Hg/kg and better than 10 ng Hg/kg for samples with less than 100 ng Hg/kg. The limit of detection for the analyses is about 1–5 ng Hg/kg, depending on the sample and the exact method of analysis. The lowest standard deviations on duplicate analyses are about 1 ng Hg/kg. The general level found in sea water is about 10 ng Hg/kg, in ground water about 50 ng Hg/kg, and in rain water about 100 ng Hg/kg.     

Determination of mercury in air by adsorption on Hopcalite and by neutron activation analysis

A new method for the determination of mercury in air has been developed. It combines the adsorption of mercury on Hopcalite (a material approved for this purpose by the National Institute of Health of the United States) and its quantification by neutron activation. The concentrations of mercury in office air in Montreal, Canada, were determined by instrumental semiabsolute neutron activation analysis. They varied from 39 to 48 ng/m³. The results were compared with the concentrations of mercury in office air determined simultaneously at the same place by cold vapour atomic fluorescence spectrophotometry. A close correlation between the results of the 2 methods was obtained. The detection limit of our method is about 14 ng/m³.     

Neutron activation analysis of mercury contents in head hair of dentists in Japan

Mercury contents in head hair of 58 dentists employed at the NUSD hospital and 50 dentists employed at the private hospitals or clinics were determined using neutron activation analysis. The arithmetic means were 5.8 ppm and 5.2 ppm, and geometric means were 5.4 ppm and 4.8 ppm, respectively. They were much lower than the values reported in the past year, and agreed well with those of normal Japanese men of the same age. Therefore, it was concluded that the mercury pollution in the working environment of dentists might be practically non-existent in Japan today.     

Substoichiometric determination of mercury by neutron activation analysis

A method has been developed for the substoichiometric determination of mercury by thermal neutron activation analysis, based on the selective extraction of the Hg(II)—Bindschedler's Green complex into 1,2-dichloroethane. The method has been applied for the determination of trace amounts of mercury in geological standards such as W-1, GR, Sye-1, and T-1, meteorite Allende de Publito, and biological materials such as kale, IR1 standard tobacco, and human blood serum.     

Determination of trace level mercury in biological and environmental samples by neutron activation analysis

Sorptivity studies with Chelex 100 column indicated chloride to be the best medium for the sorption of mercury. A radiochemical separation procedure has been developed for the determination of mercury by neutron activation analysis utilizing sorption of mercury on Chelex 100. The method was checked with Orchard Leaves and Tuna Fish standards from the National Institute of Standards and Technology.     

Analysis of Brazilian snake venoms by neutron activation analysis

Instrumental neutron activation analysis (INAA) has been applied to multielemental determinations of Brazilian snake venoms from the species: Bothrops jararacussu, Crotalus durissus terrificus and Bothrops jararaca. Concentrations of Br, Ca, Cl, Cs, K, Mg, Na, Rb, Sb, Se and Zn have been determined in lyophilized venoms by using short and long irradiations in the IEA-RI nuclear reactor under a thermal neutron flux of 10¹¹ to 10¹³ n⁰ ·cm^–2·s^–1. The reference materials NIST bovine Liver 1577 and IUPAC Bowen's Kale were also analyzed simultaneously with the venoms to evaluate the accuracy and the reproducibility of the method. The concentrations of the elements found in snake venoms from different species were compared. The Crotalus durissus terrificus venoms presented high concentration of Se but low concentrations of Zn when these results are compared with those obtained from genera Bothrops venoms.     

Determination of mercury in total diet samples by neutron activation.

The mercury contents of food samples representative of the total diet have been determined by neutron activation analysis. The mercury was separated by anion-exchange chromatography and precipitated as the sulfide. The mercury concentrations for the different fractions of total diet samples were well below 50 p.p.b. Only in the meat, fish, and poultry fraction were measurable amounts of mercury encountered regularly.     

Determination of trace elements in scalp hair of an elderly population by neutron activation analysis

Neutron activation analysis was applied to assess trace elements concentrations in head hair from healthy elderly people living in the São Paulo metropolitan area. Concentrations of As, Br, Ca, Cl, Co, Cr, Cu, Fe, K, La, Mn, Na, Sb, Se and, Zn were determined. Comparisons were made between the results obtained for dyed and non-dyed hair as well as for hair from females and males of two different age groups. The results were also compared with range values established by clinical laboratories and published data.