Determination of mercury in head hair of Brazilian populational groups by neutron activation analysis

In the present work, determination of mercury in the head hair of populational groups living near a heavily industrialized region in São Paulo and of Indians living in the Xingu park in the Amazonic region, was carried out by instrumental neutron activation analysis. A control group of people with no suspicion of contamination by mercury was also studied. The range of mercury concentrations found up to now were: for the control group from 0.26 to 02.5 ppm; for the Indians from 6.9 to 34 ppm, and for the industrialized region inhabitants: from 0.30 to 3.0 ppm.     

Differences in trace-element concentrations in hair between males and females

Hair clippings (from the head) from over a hundred persons in and around Orange County of California were analysed for mercury, gold, zinc, and copper by instrumental neutron activation analysis. The results of the study show significant differences in the trace-element distributions between males and females. For mercury, the mode of the distribution occurs at about 1 to 1,5 ppm for males and 4 to 6 ppm for females. A significant difference between the male and female distribution curves was also found for gold, and a less significant one for zinc and copper. This study indicates the possibility that the high levels of mercury and gold in the hair of females are more likely due to external contamination, because of the more frequent and intense exposure of their hair to cosmetics. Moreover, as females usually have longer hair, their hair strands are exposed to such treatment over a longer period of time. Hair being a good ion-exchange material, trace elements are absorbed easily during the process of washing and setting of hair, and accumulation of these over a long period may cause a very high concentration of these elements. The variability of trace-element concentration as a result of external contamination, and the sometimes marked variation along the length of the hair, pose a serious problem in forensic work. Identification criteria should provide for these variations, especially in the case of mercury and gold. This work also indicates that if the evidence hair from the scene of a crime does not contain the root end, its value as an evidence specimen is considerably reduced.     

Monitoring and abatement of environmental mercury pollution using human hair as absorbant

Mercury pollution in the industrial environment of Chile has been studied using hair as a monitor. Data from samples representing people living in the non-polluted and also from the polluted areas show that, hair is an effective and convenient indicator of environmental mercury pollution in Chile. A major source of mercury pollution and its transport is contaminated water. Hair is found to concentrate mercury from water to an extent of 80 to 500 fold increase in hair concentration. This absorption occurs in a contact time of 24 h and thus provides a means of treating mercury containing water to reduce the mercury to acceptable levels. The capacity of hair for this purpose is about 0.2% which means that, with a kilogram of hair /valued at less than 25 cents/ nearly 20.000 litres of contaminated water /at 0.1 ppm mercury/ can be treated. This is an inexpensive and convenient alternative to conventional ion-exchange processes which are generally very expensive, particularly for developing countries.     

Determination of Trace Amount of Mercury in Human Hair by Neutron Activation Analysis

Trace amount of mercury in human hair has been determined by destructive neutron activation analysis. It was found that the contents of mercury in the hair of normal people in Taiwan area is the order of 6 ppm. It is of interest to point out that very little fluctuation is observed in the contents of mercury in human hair regardless of sex and age of the normal people under investigation. On the other hand for those people who are working in the caustic soda manufacturing plant in which mercury is used as cathode in the electrolysis process of saline water, the mercury contents in their hair are definitely much higher (ca. 30 times) than the average values of normal people.     

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.     

Bestimmung von jodid auf grund seiner katalytischen wirkung mittels der jodat-arsenit-reaktion

The catalytic action of iodide on the iodate-arsenite reaction can lie used to detect 0.5 μg of iodide at a dilution limit of 1:10⁷. The reaction time is inversely proportional to the iodide concentration so that a chronometric estimation of iodide is possible; the “simultaneous comparison” method is advantageous, being independent of temperature variations. The relative errors are ± 10% in the range 1–10 μg 1-, and ± 5% in the range 10–50 μg 1-. Silver and mercury ions interfere.     

Relationships between NMR shifts and interaction energies in biphenyls,alkanes, aza-alkanes,and oxa-alkanes with X─H…H─Y and X─H…Z (X,Y = C or N; Z = N or O) hydrogen bonding

Hydrogen–hydrogen C─H^…H─C bonding between the bay-area hydrogens in biphenyls, and more generally in congested alkanes, very strained polycyclic alkanes, and cis-2-butene, has been investigated by calculation of proton nuclear magnetic resonance (NMR) shifts and atom–atom interaction energies. Computed NMR shifts for all protons in the biphenyl derivatives correlate very well with experimental data, with zero intercept, unit slope, and a root mean square deviation of 0.06 ppm. For some congested alkanes, there is generally good agreement between computed values for a selected conformer and the experimental data, when it is available. In both cases, the shift of a given proton or pair of protons tends to increase with the corresponding interaction energy. Computed NMR shift differences for methylene protons in polycyclic alkanes, where one is involved in a very short contact (“in”) and the other is not (“out”), show a rough correlation with the corresponding C─H^…H─C exchange energies. The “in” and “in,in” isomers of selected aza- and diaza-cycloalkanes, respectively, are X─H^…H─N hydrogen bonded, whereas the “out” and “in,out” isomers display X─H^…N hydrogen bonds (X = C or N). Oxa-alkanes and the “in” isomers of aza–oxa-alkanes are X─H^…O hydrogen bonded. There is a very good general correlation, including both N─H^…H─Y (Y = C or N) and N─H^…Z (Z = N or O) interactions, for NH proton shifts against the exchange energy. For “in” CH protons, the data for the different C─H^…H─Y and C─H^…Z interactions are much more dispersed and the overall shift/exchange energy correlation is less satisfactory.     

Highly sensitive electrochemical detection of mercury (II) via single ion-induced three-way junction of DNA

A “signal-on” electrochemical sensing strategy was designed for highly sensitive and selective detection of mercury (II) via its induction to three-way junction of DNA (DNA-TWJ). The TWJ consisted of the capture probe that was self-assembled on a gold electrode surface through SAu bond, the signal probe that was labeled with ferrocene (Fc) and contained single T–T mismatch to capture probe, and an assistant probe for the formation of DNA-TWJ upon the presence of mercury (II). This process caused the Fc tag approaching the electrode for fast electron transfer and thus increased the oxidation current. The “signal-on” sensing method could detect Hg^2 + ranging from 0.005 to 100 nM. The assay was simple and fast. It showed potential application in on-site and real-time Hg^2 + detection.     

Standardization of methods for the determination of traces of mercury: Part 5. Determination of Total Mercury in Water

For the determination of total mercury in water, two procedures based on cold-vapour atomic absorption spectrometry are given, each with and without a concentration step. These procedures have been accepted as reference methods by the member companies of the Bureau International Technique du Chlore. The methods give reliable results down to a concentration of 0.2 μg of mercury per litre of water. Results of an interlaboratory test involving 22 laboratories are reported. At the 0.75 μg Hg l^-1 level the results did not differ significantly; the coefficient of variation for repeatability was 3.8–10.9% and the coefficient of variation for reproducibility 7.2–29.4% for the different methods.     

New insights into the impact toughness of ASA (acrylonitrile-styrene-acrylate) with controllable core–shell structure synthesized by three-stage seeded emulsion polymerization

Acrylonitrile-styrene-acrylate (ASA) with controllable core–shell structure was prepared through three-stage seeded emulsion polymerization. A series of characterizations had been performed to study the effect of different core–shell ratios on the properties of ASA. The most interesting was that the impact strength of ASA exhibited a “wave” variation instead of a linear variation with the increasing loading content of poly(butyl acrylate) (PBA) core. Moreover, the threshold of impact strength appeared at 49.725?wt% PBA content, nearly 33 kJ/m². To explain this unusual variation, an impact schematic was proposed.     

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.     

Novel Screen-Printed Gold Nano Film Electrode for Trace Mercury(II) Determination Using Anodic Stripping Voltammetry

Integrating the screen printing technique with the vacuum evaporation method, we developed a novel and disposable screen-printed gold film electrode (SPGFE) in the present work. First, a conductive silver layer, a connection graphite-carbon layer, and an insulating polymer layer were successively printed onto a flexible polyethylene terephthalate (PET) substrate. Then, a gold thin film was achieved on the scheduled vacant site by use of the vacuum evaporation method. In order to enhance the electroanalytical performance of the SPGFE, the thickness of the gold film was controlled in the range of 70–80 nm under optimum conditions. The fabricated SPGFE was applied to detect trace mercury(II) based on the square-wave anodic stripping voltammetry (SWASV). The results indicated that the proposed SPGFE exhibited higher sensitivity to trace mercury(II) than the gold disc electrode. The stripping current was linearly related to the concentration of mercury(II) in the range of 16–280 µg/L (R² = 0.9919) and 1.2–8.0 µg/L (R² = 0.9977), with a detection limit of 0.8 µg/L (S/N = 3) under 180 s accumulation. The SPGFE was further used to detect mercury in real samples, and the obtained results revealed a good agreement with those of inductively coupled plasma atomic emission spectrometry (ICP-AES) and atomic absorption spectroscopy (AAS). The highly sensitive and environmental friendly electrode, as another type of “mercury-free” electrode, holds great promise in stripping measurements.     

Gold electrodes from recordable CDs for mercury quantification by flow injection analysis

The development of a new methodology for the construction of very efficient flow cells for mercury detection by potentiometric stripping analysis, employing the thin gold layer of recordable CDs as working ¶electrode is reported. This new source of electrodes (CDtrodes) show very attractive performance, similar to that obtained with commercial gold electrodes, with superior versatility. The low cost of this new source of “gold electrodes” allows a frequent replacement of the electrode, avoiding cumbersome clean-up treatments. Various experimental parameters have been optimized to yield low detection limits (0.25 ng/mL of mercury for 5 min deposition at 0.3 V) and good precision (standard deviation of 1.9% was obtained for 15 repetitive measurements using 10 ng/mL of mercury). Standard curves were found to be linear over the range of 0.5–100 μg L^–1 of mercury. The flow cells developed were used for the quantification of mercury in oceanic and tap water.     

极谱分析人员头发、指甲和尿中的汞含量及其评价

为查明汞在极谱分析人员体内吸收、积累与排泄情况，用无火焰原子荧光法测定了２１例极谱分析人员（检查组）和２２例非接触汞人员（对照组）头发、指甲和尿中的汞．结果表明，检查组头发、指甲和尿中汞含量均明显高于对照组（Ｐ＜０．００１）；性别之间无显著差异（Ｐ＞０．０５）；汞的积累与接触汞史有关，与年龄无关．发汞和指甲汞远比尿汞高，且含量稳定，因而头发和指甲的监测可作为血清和尿分析的补充手段，在职业病及环境医学方面甚至可代替尿汞监测。     

Versuche zur Anreicherung von Edelmetallspuren in Reinstquecksilber durch partielles Lösen der Matrix

Trace impurities of gold and palladium in metallic mercury can be enriched in a simple way by partially dissolving the sample in nitric acid. Practically the whole trace content of the sample will be collected in the residue. Up to at least 100 g Hg the quantity of the mercury sample has no influence on the trace enrichment. After the partial dissolution of the metal the enriched gold was determined photometrically with Rhodamine B as a reagent, Pd was determined as [PdJ₄]^2? complex. For the analysis of metallic mercury containing 0.5 ppm of Au and 2 ppm of Pd the relative standard deviation is 0.046, respectively 0.037. The limit of detection was found to be at 0.2 ppm for both the elements. Using this method, the enrichment of traces of silver in mercury is not possible.     

On-line determination of mercury in river water at the German monitoring station Schnackenburg/Elbe

A monitor is described which provides the on-line determination of mercury in river water at concentrations from 20 to 1000 ng/L. The measurement includes an on-line digestion with Br^–/BrO₃ ^– and UV-radiation. Each determination is controlled by an on-line addition of 50 and 100 ng/L mercury carried out by pre-dilution of a 500 and 1000 ng/L stock solution using sequential injection analysis (SIA). One cycle of analysis takes 20 min and results in nine signals. A five days stand-alone operation has been performed successfully. Details are also published at web page: “http/www.rzbd.fh-hamburg.de/¶～prmercol”     

A New Approach for Voltammetric Determination of Nefopam and its Metabolite

In present paper we described a new simple voltammetric method of determination of nefopam alkaloid and its metabolite – N‐oxide. N‐oxide of nefopam is reduced at the dropping mercury electrode (DME) and silver solid amalgam electrodes (AgSAE), which can effectively replace mercury and chemically modified electrodes. The reduction consists of two one‐electron stages each accompanied with one proton transfer. N‐oxide of nefopam can be obtained from nefopam substance by oxidation with potassium peroxymonosulfate. It was studied the effect of various factors on N‐oxide quantitative yield (pH, oxidation duration, reagents concentration) as well as on the reduction of N‐oxide at DME and p‐AgSAE (pH, the nature of background electrolyte, potential and time of accumulation). It was showed that the reduction current linearly increased with increasing of concentration of analgesic. Limit of quantiation is 10^?6 mol L^?1 at DME and 10^?7 mol L^?1 at p‐AgSAE. The developed method was applied for the analysis of commercial drug solution for injection “Nefopam” with recovery of 96.7 %, as well as for the spiked human urine samples. Excellent repeatability with a relative standard deviation below 5 % was achieved.     

Determination of alkylmercury compounds in fish tissue with an atomic absorption spectrometer used as a specific gas chromatographic detector

Atomic absorption spectrometry is used as a specific gas chromatography detector in the determination of alkylmercury compounds in fish. An electrical furnace “cracks” the organic mercury molecules in the Chromatographic effluent. An extraction procedure has been developed which improves the precision of the method. The detection limit is 0.3 ppm of mercury for 0.5-g samples.     

Potentiometric stripping analysis for mercury

In potentiometric stripping analysis for mercury, elemental mercury is deposited on a glassy carbon electrode surface by means of potentiostatic reduction. It is then oxidized by potassium permanganate added to the sample prior to analysis and the “redox titration curve” thus obtained is recorded on a high-input impedance recorder. Deaeration of the sample is unnecessary. The analytical range is 5 × 10^-9–10^-3 M mercury(II), the times needed for potentiostatic accumulation ranging from 64 min at 10^-8 M to 1 min at concentrations above 10^-6 M. The chemistry of the stripping process is discussed and an automatic instrument for potentiometric stripping analysis is described.     

A rapid,simple method for the determination of total mercury in fish and hair by cold-vapour atomic absorption spectrometry

Fuming nitric acid and acidified potassium permanganate are used to pre-digest fish or hair samples in Pyrex culture tubes. Cold-vapour atomic absorption spectrometry is used to detect the elemental mercury which is generated by reduction in a syringe. The absolute detection limit of the method is 0.66 ng Hg, and at levels of 0.14 and 0.60 parts per million (ppm) the standard deviations are ± 0.009 and ±0.008 ppm, respectively. One person can handle batches of 50–100 samples per day including standards and blanks.