Daily dietary intake of trace elements of radiological and nutritional importance by the adult Indian population

The concentrations of eleven trace elements: Ca, Co, Cr, Cs, Fe, I,K, Se, Sr, Th and Zn were determined in total diet samples and also in individualfood materials which constitute the typical Indian diet. Instrumental neutronactivation analysis (INAA) and radiochemical neutron activation analysis (RNAA)were employed for the analysis. Whereas the elements Fe, Co, Cr, Se and Znare important from the view point of their role in nutrition, the elementsCs, K, Sr and Th are of importance in radiation protection, and Ca and I havedual importance: both in nutrition as well as in radiation protection. Basedon the analysis of twenty total diet samples, prepared as per the data onthe dietary intake pattern of four provinces of India and the data on intakepattern of an average adult Indian, the geometric mean (GM) intake of variouselements was estimated to be 0.33 g (0.2–0.67) for Ca, 16.5 µg(8.3–31.1) for Co, 52.3 µg (35.1–131) for Cr, 4.7 µg(2.79–11.8) for Cs, 94.6 µg (60.6–201) for I, 1.90 g (1.25–3.54)for K, 1.13 mg (0.78–2.97) for Sr, 0.76 µg (0.45–1.66) forTh, 15.9 mg (10.2–34.3) for Fe, 56.3 µg (27.6–105.3) forSe and 8.6 mg (5.1–16.7) for Zn. Some of the important individual foodmaterials, such as cereals, pulses, milk, vegetables etc., were also analysedfor these elements to observe the contributions of the individual food materialsto their daily dietary intake. The results of the analysis showed that inthe case of Cs, K, Sr, Th, Fe, Zn and Co, almost 50% of the daily dietaryintake of the above stated elements is contributed by cereals and pulses.In the case of Ca however, significant amount is contributed by milk and incase of I, iodised salt could make significant contribution. The data collectedso far, for Se and Cr, was not sufficient to draw any definite conclusion.     

Determination of mineral constituents in duplicate portion diets of two university student groups by instrumental neutron activation

Concentrations of 15 elements were determined simultaneously in duplicateportion diets of two university student groups from So Paulo Universityconsisting of nine women (20–23 years) and ten men (20–24 years).Thediet samples were prepared by either freeze-drying or drying in a ventilatedoven. About 100–200 mg of diets were irradiated for 2 minutes and 8hours in the IEA-R1m research reactor and Br, Ca, Cl, Co, Cr, Cs, K, Fe, Mn,Mg, Mo, Na, Rb, Se, and Zn were determined by instrumental neutron activationanalysis (INAA). The average daily intakes found in the women and men groupswere: 2.1 and 4.3 mg of Br, 501 and 707 mg of Ca; 3.1 and 6.0 g of Cl; 12and 25 mg of Co; 15 and 36 µg of Cs; 53 and 63 µg of Cr; 5.1 and10.8 mg of Fe; 1.3 and 2.8 g of K; 134 and 306 mg of Mg; 1.3 and 4.1 mg ofMn; 134 and 302 mg of Mo, 2.0 and 4.1 g of Na; 2.4 and 4.6 mg of Rb; 29 and41 µg of Se; 6.2 and 10.6 mg of Zn, respectively. The daily intakesof Ca, Se and Zn in both groups and Fe in the women groups appeared to bebelow the U.S. RDA recommendations. For the elements Na and Cl the daily intakeswere higher than the recommended values by RDA.     

The status of trace and minor elements in some Bangladeshi foodstuffs

An investigation is conducted on the status of trace and minor elements in some foodstuffs (cereals, vegetables, milk, egg and fish), commonly consumed in Bangladesh, using proton induced X-ray emission (PIXE) and radioisotope-induced X-ray fluorescence (XRF) techniques. In PIXE measurements, the samples were irradiated in air with 2.0 MeV (energy on the target) protons having the beam intensity of 30 nA for characteristic X-ray excitation, while in XRF analysis, the samples were excited for 5000 seconds with a 10 mCi Cd-109 annular X-ray source. The elemental concentration of K, Ca, Mn, Fe, Ni, Cu, Zn, Se, As, Br, Rb, Sr, Mo, and Pb were determined in the samples by comparison with X-ray yield curves constructed from IAEA and NBS standard reference materials. The validity of the analytical procedures (PIXE and XRF) followed in this study has been confirmed by comparative measurements of Cu, Zn and Mn in some varieties of rice with atomic absorption spectrophotometry. The results indicate that none of the food regimes investigated here is burdened with heavy metals beyond permissible limits except five species of vegetables with chromium having the range of 0.99–3.59 mg/kg compared to the literature value of 0.0–0.36 mg/kg (dry weight basis). An average value of 0.2 mg/kg of arsenic was observed both in IRRI (n=16) and local Aman (n=12) varieties of rice and only one hen egg contained 1.7 mg/kg of lead in yolk. The zinc content in some marine fish from Bay of Bengal was reported to be 5.4–19.5 mg/kg, whereas in the present study of sweet-water fish, the level is found to be 15.2–62.1 mg/kg (fresh weight basis) for five species. In human milk, both Cu (0.12–0.25 mg/l, n=8) and Zn (0.28–1.80 mg/l, n=8) levels appear to be almost half the literature values (n=25). On the other hand formula milk has higher values of Cu (0.32–1.63 mg/kg, n=16) and Zn (5.16–19.8 mg/kg, n=16).     

Analysis of toxic trace elements in sea food samples by neutron activation

The aim of this study is to investigate the contents of toxic and essential trace element such as As, Hg, Se and Zn by neutron activation analysis in coastal fishes consumed by the general population of Malaysia. The mean values of the elements analysed expressed in mg/kg fresh weight ranged 1.42–5.61, 0.06–0.42, 4.2–20.6, 0.41–1.28 for As, Hg, Zn and Se, respectively. The maximum permissible limit for As in food was set at 1.0 mg/kg under the Malaysian Food Regulations. Our results showed that consumption of coastal fishes is not permitted under the regulations, while the levels of Hg, Se and Zn were within the permissible limits. The daily dietary intake of As and Hg at 400 g and 30g respectively are still within the tolerance levels.     

Selenium and nutrition: The accuracy and variability of the selenium content in commercial supplements

Summary Selenium is a required trace-element that has been found to be protective against serious chronic diseases such as cancer and cardiovascular disease in some, but not all, epidemiological studies using both case-control and intervention designs. As a result, the fraction of the adult U.S. population now taking a daily selenium supplement is steadily increasing. In this study, we analyzed 10 or more replicate Se supplement tablets, from each of 15 different products representing 12 different brand names with most being sampled at two different times separated by approximately 30 months. Two chemical forms, seleno-yeast and selenate were tested in 50, 100 and 200 µg/tablet dosages (seleno-yeast) and 25 and 200 µg/tablet dosages (selenate). Variations in contemporary lots were evaluated at both sampling periods. The Se content provided on the product label is generally understated. One tablet contained 2.5 times more selenium than the stated dose. Selenate supplements are less accurately labeled and more highly variable compared to yeast supplements. One popular multivitamin, labeled at 200 µg/tablet, contained tablets in excess of 300 µg. Many subjects using this supplement will exceed the 400 µg/day tolerable upper limit of intake, recently established, for Se by the Institute of Medicine’s Food and Nutrition Board.     

Investigation of the appearance of supplemental enriched Se-76 using the human nail as a dietary monitor

The principal objective of this study was to determine if the use of a stable enriched tracer of Se-76 could be used to determine the delay time between a dietary intake of selenium and its appearance in fingernails and toenails. Selenium is an essential trace element in human nutrition. It has been studied at the Missouri University Research Reactor (MURR) for the past 15 years using an Instrumental Neutron Activation Analysis (INAA) technique. The principal route of human exposure to selenium is through the diet. Selenium concentrations of nails, blood, hair, and urine have been used as indicators of dietary selenium intake. In this study, a cohort consisting of seven men and five women ingested three selenium supplements of 150 g each over a three day period. The selenium was enriched in Se-76 (96.48%) and ingested as selenite in orange juice following an overnight fast. Fingernails and toenails were collected prior to the selenium supplementation and for several months afterward to be used as biochemical indicators. The peak⁷⁶Se concentration in the fingernails and toenails occurred at 19–23 and 16–32 weeks after supplementation, respectively.     

Selenium status in Turkey

Measured (n = 36, 51 ·g/day) and estimated (n = 274, 44 ·g/day) dietary daily intake of selenium in Turkey is low compared to the RDA value of 55 ·g Se/day. When the existence of high prevalence of iodine deficiency in most part of the country is considered, adequate level of dietary Se becomes more important. We have found recently that high iodine-deficient goitrous children had lower Se levels and antioxidant enzyme (AOE) activities, and higher levels of DNA base lesions than non-goitrous controls. This revised version was published online in August 2006 with corrections to the Cover Date.     

Development and application of a simple routine method for the determination of selenium in serum by octopole reaction system ICPMS

The aim of the study was to develop an inductively coupled plasma mass spectrometry (ICPMS) method for robust and simple routine determination of selenium in serum. Polyatomic interferences on ⁷⁶Se, ⁷⁷Se, and ⁷⁸Se were removed by applying an octopole reaction system ICPMS with the reaction cell pressurized with H₂ gas. We developed a novel simple optimization routine for the H₂ gas flow based on a signal-to-noise ratio (SNR) calculation of the selenium signal measured in a single selenium standard. The optimum H₂ flow was 2.9 mL min^–1. The selenium content in serum was determined after a 50-fold dilution with 0.16 M HNO₃ and quantified by using addition calibration and gallium as an internal standard. The method detection limit was 0.10 g L^–1 for ⁷⁶Se and ⁷⁸Se and 0.13 g L^–1 for ⁷⁷Se. Human serum samples from a case-control study investigating if selenium was associated with risk of colorectal adenoma were analyzed. The average selenium concentration for the control group (n=768) was 137.1 g L^–1 and the range was 73.4–305.5 g L^–1. The within-batch repeatability (a batch is ten samples) estimated from 182 replicate analyses was 6.3% coefficient of variation (CV), whereas the between-batch repeatability was 7.4% CV estimated from 361 replicates between batches. The method accuracy was evaluated by analysis of a human serum certified reference material (Seronorm Serum level II, Sero A/S, Norway). There was a fairly good agreement between the measured average of 145±3 g L^–1 (n=36) and the certified value of 136±9 g L^–1. In addition the method was successfully applied for analysis of zinc serum concentrations without further optimization. For the Seronorm certified reference material a value of 911±75 g L^–1 (n=31) for zinc was obtained, which corresponds well to the certified zinc value of 920±60 g L^–1.     

Radioisotope excited EDXRF analysis of sediment core samples from the southern part of the Black Sea +

In all 43 sediment samples were collected as gravity cores in depthfrom 70 to 150 cm, from the 20 sampling sites of the continental slope ofthe southern part of the Black Sea, during 1978. The samples were quantitativelyanalyzed by radioisotope excited energy dispersive X-ray fluorescence spectrometry(EDXRF) using fundamental parameter technique (FTP). The investigated sedimentsamples were the organic rich-mud components of the core samples, which wereknown as rich in metals. The metal concentration ranges were as follows: Ca(3.1–12.9%), Ti (1000–2000 µg/g), V (40–150 µg/g),Cr (30–200 µg/g), Mn (200–1500 µg/g), Ni (25–100µg/g), Cu (20–70 µg/g), Zn (20–50 µg/g), Br(15–670 µg/g), Rb (5–90 µg/g), Sr (80–700 µg/g),Y (10–20 µg/g), Mo (10–111 µg/g), Zr (20–190µg/g), Cd ( <1–5 µg/g), Sb ( <1–5 µg/g),I (10–430 µg/g), Ba (100–1650 µg/g), La (5–18µg/g), Ce (12–38 µg/g) and Nd (6–17 µg/g). Thesediment cores systematically collected in 1978 by Mineral Research and ExplorationInstitute of Turkey (MTA) are the oldest available sediment samples from theTurkish coastline of the Black Sea. Therefore, the results may be used asreferences for monitoring possible future metal pollution.     

Rapid speciation of Se(IV) and Se(VI) by flow injection–capillary electrophoresis system with contactless conductivity detection

A flow injection–capillary electrophoresis system with contactless conductivity detection and hydrostatic-pressure-generated flow was used for the fast and sensitive speciation of Se(IV) and Se(VI). The sample throughput was 25 samples per hour using a background electrolyte solution containing 8.75 mM l-histidine (His) adjusted to pH 4.00 with acetic acid. The repeatability of peak areas (n=8) was better than 1.41% and the limits of detection were 190 g L^–1 and 7.5 g L^–1 for Se(IV) and Se(VI), respectively. The interference from carbonate, typically present in water samples, was eliminated by using a low-pH electrolyte in which carbonate is uncharged and migrates at the EOF front. The method was applied to the analysis of Se(IV) and Se(VI) in soil samples that were spiked with both selenium species and the results for recovery of both selenium species were in good agreement with their introduced concentrations.     

Rapid multi-element analysis of groundwater by high-resolution inductively coupled plasma mass spectrometry

A rapid and sensitive method was developed to determine, with a single dilution, the concentration of 33 major and trace elements (Na, Mg, Si, K, Ca, Li, Al, P, S, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Cd, In, Sn, Sb, Cs, Ba, Re, Hg, Pb, Bi, U) in groundwater. The method relies on high-resolution inductively coupled plasma mass spectrometry (HR ICP-MS) and works across nine orders of magnitude of concentrations. For most elements, detection limits for this method are considerably lower than methods based on quadrupole ICP-MS. Precision was within or close to ±3% (1) for all elements analyzed, with the exception of Se (±10%) and Al (±6%). The usefulness of the method is demonstrated with a set of 629 groundwater samples collected from tube wells in Bangladesh (Northeast Araiharzar). The results show that a majority of tube well samples in this area exceed the WHO guideline for As of 10 g L^–1, and that those As-safe wells frequently do not meet the guideline for Mn of 500 µg L^–1 and U of 2 µg L^–1.     

Relationship between the cervical uterine cancer evolution and selenium concentration in urine determied by NAA

Neutron activation analysis of Se in urine reaches an optimum sensitivity (few ppb) and precision (±12%) when the traces are complexed without using a carrier by ammonium pryrrolidindithiocarbamate (APDC) at pH 1.5–2 and adsorbed on activated carbon filters. In this way the selenium traces analysis have been carried out through^77mSe in 45 urine samples on a pre-separation basis by cyclic activation ofthe carbon filters. The selenium concentration in our blanks is virtually zero, because APDC proved to be selnium free and selenium mass in 50 mg of activated carbon used as a filter is 20 times below our qualitative detection limit and 144 times below our quantitative detection limit. The samples were first of day urine from healthy and ill women suffering cervical uterine cancer, at different evolution stages: incipient, intemediate and advanced, with no treatment, and surgery, radiotherapy, chemotherapy, or a combined treatment. The results show a consistent tred to increase the selenium trace concentration during the intemediate stage, whereas it is the same than nomal for incipient cases, and it decreases to the lowest concentrations for advanced cases.     

Accumulation and distribution of elements in rice /seed,brand layer,husk/ by neutron activation analysis

Various rice samples /seed, brand layer, husk/ from Vietnam were analyzed for Se, Hg, Cr, Ni, Sc, Rb, Fe, Zn and Co by neutron activation analysis. The concentration values found /seed/ were the following: Se 0.04–0.07 ppm, Hg 0.02–0.07 ppm, Cr 2.13–8.65 ppm, Ni 1.56–4.95 ppm, Sc 0.02–0.06 ppm, Rb 0.84–2.71 ppm, Fe 26.31–96.07 ppm, Zn 10.65–27.39 ppm and Co 0.02–0.15 ppm. The values were reported in ppm /dry weight/. Statistical analysis /t-test, t=0.05/ showed that the content of elements varies between sorts of rice; the content of Rb, Fe, Ni, Cr of rice husk was significantly higher than in rice seed and brand layer.     

Determination of Selenium(IV) by Stripping Voltammetry at a Mercury-Film Electrode

A procedure was proposed for the determination of selenium(IV) by stripping voltammetry on a mercury-film electrode at an electrolysis potential of +0.4 V versus the saturated silver–silver chloride reference electrode in a 1 M H₂SO₄ solution. The current of the cathodic peak is a linear function of the selenium(IV) concentration in the range from 5 × 10^–3 to 3 × 10^–1 mg/L (6.3 × 10^–8 to 3.8 × 10^–6 M) at a time of electrolysis of 30 s (t _el). The detection limit for selenium is 1 × 10^–4 mg/L (1.3 × 10^–9 M) at t _el = 300 s. It was shown that selenium(IV) can be determined in the presence of 10 mg/L Zn(II), 1 mg/L Cd(II), 0.5 mg/L Pb(II), and 0.2 mg/L Cu(II). A procedure for the determination of selenium in natural, mineral, and potable water was proposed.     

Activation analysis of Se in biological samples through75Se and77mSe

A method is described to separate trace amounts of selenium in biological samples without using a carrier. This method is based on the adsorption on active carbon of the complex ion formed with APDC /ammonium salt of l-pyrrolidine carbodithioic acid/ at pH 1. The efficiency of the radiochemical separation described is measured by using carrier-free⁷⁵Se labelled solutions of sodium selenite at selenium concentrations from 3.5×10^–8 to 3.5×10^–11 g ml^–1. The results were between 95% and 98% with statistical variations from 2% to 10%. The determination of selenium can be made following this separation either through⁷⁵Se in the traditional way, or through^77mSe if the separation is performed prior to irradiation. The detection limits on the available conditions were 0.01 ppm for⁷⁵Se and 0.1 ppm for^77mSe. When the analysis is performed through⁷⁵Se /t=120 d/, the statistical error is notably smaller because the counting time may be considerable, whereas through^77mSe/t=17.5 s/it is higher than 20%, depending on the concentration and the available neutron flux. However, the advantages of gaining time and the fact of performing the trace separation from a non radioactive material, make both procedures competitive as useful tools for the research on the function of Se in vertebrates.     

Updated estimates of the selenomethionine content of NIST wheat reference materials by GC–IDMS

Updated estimates of the selenomethionine content of four NIST wheat reference materials have been obtained by use of a revised gas chromatography–stable-isotope dilution mass spectrometric method. The revised method makes use of digestion with methanesulfonic acid, which enables more complete recovery of endogenous selenomethionine than was previously achieved by overnight denaturing treatment in 0.1 mol L⁻¹ HCl. The NIST wheat reference materials each contain approximately 55% of their total Se content as selenomethionine. Information about forms of Se in reference materials adds value to these materials in Se speciation studies. Estimates of selenomethionine content are also provided for other wheat samples, including several grown under conditions of exposure to high Se levels. These samples also contain approximately 55% of their total Se content as selenomethionine. The consistent level of 55% of total selenium occurring in the form of selenomethionine when the total selenium content varies by a factor of 500 is suggestive of an active mechanism of incorporation of selenium into wheat grain. Figure Selenomethionine content of wheat samples     

Speciation of selenium in selenium-enriched shiitake mushroom, Lentinula edodes

The major selenium compound in an aqueous extract of the most popular mushroom in Eastern Asian countries, shiitake (Lentinula edodes), fortified with selenium (Se) was identified by means of hyphenated techniques, i.e. HPLC-inductively coupled argon plasma mass spectrometry and HPLC-electrospray ionization mass spectrometry (HPLC–ICP MS and HPLC–ESI MS). Sixty-eight per cent of the total Se in the selenized shiitake was extracted with water, and 49.8% of the Se in the water extract was eluted in the high molecular mass fraction (>40,000 kDa) before incubation at 37 °C. After incubation, 40.6% of the Se in the water extract was eluted in a lower molecular mass fraction and the Se eluted in the high molecular mass fraction had decreased to 14.0%, suggesting that the major selenium compound in the water extract was initially in a form bound to macromolecule(s) and was then enzymatically liberated from the macromolecule(s). The retention time of the liberated selenium compound in HPLC–ICP MS matched that of selenomethionine (SeMet), and the masses of molecular and fragment ions detected by HPLC–ESI MS also suggested that the selenium compound was SeMet. The selenized shiitake accumulated Se as SeMet, and SeMet might be bound to the water extractable high molecular mass protein(s).Electronic Supplementary Material Supplementary material is available for this article at     

Determination of selenium daily intakes in two small groups of the Portuguese population by replicate sample neutron activation analysis

Selenium daily intake was determined for two small groups of the Portuguese population, based on the analysis of duplicate diet portions. The total amount of food ingested during a day was collected for 18 workers of the Technological and Nuclear Institute (ITN-Sacavém) and for 6 females of Reguengos de Monsaraz, a small town in the south-eastern hinterland. The average selenium daily intake was 43 ± 20 and 32 ± 13 μg per person, respectively, both lower than the Recommended Dietary Allowance (RDA) of 55 μg day⁻¹. Selenium in diet samples was determined by replicate sample neutron activation analysis (RSINAA). The method was considered accurate for the selenium determination.     

Sequential speciation of selenium by flow injection cathodic stripping voltammetry

A semi-automatic continuous method for the determination of Se(IV) based on flow-injection cathodic stripping voltammetry (FICSV) is reported. The flow injection approach incorporates a thin mercury film on glassy carbon as the working electrode, on which Se(IV) is deposited at an applied potential of 0.0 V. A cathodic scan (from 0.0 to –0.9 V) is applied and the Se is stripped at –0.54 V, providing a current intensity proportional to the Se(IV) concentration in the sample. This method features a linear determination range between 0.5 and 30 ng/ml (r²=0.998, RSD=3.6%). The non-interference levels (foreign species to analyte ratio) are 2.5:1 for Cu(II), 7.5:1 for Pb(II), 35:1 for Cd(II), 250:1 for Zn(II) and 500:1 for Fe(III). After developing the method for Se(IV), the speciation of this element has been performed by sequential injection of the dissolved sample into a carrier which may or may not have been previously reduced off-line thus determining the sum (Se(IV)+Se(VI)) or only Se(IV), respectively. The method has been applied to selenium speciation in water samples.     

Nondestructive Synchrotron Radiation X-Ray Fluorescence Imaging of Trace Elements on Methylmercury and Selenium Administered Guinea Pigs

Abstract

The dynamics of the brain distributions of Hg, Zn, Cu and Se in guinea pigs exposed to methylmercury and selenium were examined by X-ray fluorescence imaging utilizing synchrotron radiation.

Male Hartley guinea pigs were administered methyl mercury chloride and/or sodium selenite every day for ten days (s.c. 3mg as Hg/kg/day, mole ratio Hg:Se=1:1). Two dimensional distributions of Hg, Zn, Cu and Se in guinea pig brain were observed by nondestructive X-ray fluorescence imaging. Using the