Determination Of Mercury In Hair Research Articles

Determination of mercury in hair of children

Although high or repeated exposure to different forms of Hg can have serious health consequences, the most important toxicity risk for humans is as methylmercury (MeHg) which exposure is mainly through consumption of fish. Generally, more than the 80% of Hg in hair is as MeHg, which is taken up by hair follicles as MeHg-cysteine complexes. In this context, hair samples were collected from 200 children (7 years) living in a coastal site in the North-East (A) of Italy and from 299 children (6–11 years) living in a urban area of South of Italy (B) to determine the levels of MeHg. Considering the neurotoxicity of MeHg, children were subjected to cognitive and neuropsychological tests. The hair values of Hg in the children population groups were comparable with data reported in other international surveys. On the other hand, combining results of the neurological tests with Hg levels, a possible relationship between Hg and an increase of the errors average reported in some neurological tests has been noted. Although the Hg levels were not elevated, a possible neurological influence in children, a population more susceptible than adults, might not be excluded, but the influence on neurological performances of the children could be also due to the family environment (socio economic status, educational level, etc.).

Determination of mercury in hair: Comparison between gold amalgamation-atomic absorption spectrometry and mass spectrometry

Mercury is a heavy metal that causes serious health problems in exposed subjects. The most toxic form, i.e., methylmercury (MeHg), is mostly excreted through human hair. Numerous analytical methods are available for total Hg analysis in human hair, including cold vapour atomic fluorescence spectrometry (CV-AFS), inductively coupled plasma mass spectrometry (ICP-MS) and thermal decomposition amalgamation atomic absorption spectrometry (TDA-AAS). The aim of the study was to compare the TDA-AAS with the ICP-MS in the Hg quantification in human hair.After the washing procedure to minimize the external contamination, from each hair sample two aliquots were taken; the first was used for direct analysis of Hg by TDA-AAS and the second was digested for Hg determination by the ICP-MS. Results indicated that the two data sets were fully comparable (median; TDA-AAS, 475ngg−1; ICP-MS, 437ngg−1) and were not statistically different (Mann-Whitney test; p=0.44). The two techniques presented results with a good coefficient of correlation (r=0.94) despite different operative ranges and method limits. Both techniques satisfied internal performance requirements and the parameters for method validation resulting sensitive, precise and reliable. Finally, the use of the TDA-AAS can be considered instead of the ICP-MS in hair analysis in order to reduce sample manipulation with minor risk of contamination, less time consuming due to the absence of the digestion step and cheaper analyses.

Fast and accurate methodology for direct mercury determination in hair and nails

AbstractA solvent-free, easy, fast and waste-free methodology was developed for the determination of total mercury levels in hair and nails. Samples were taken from several volunteers and directly analysed, with levels of mercury in the range between 0.5 and 8 ng/mg. The influence of quantity of hair, as well as the addition of small amount of solvent and the necessity of previous treatment were studied. Also, a history of mercury exposure was provided by the distance of the hair from the scalp of each volunteer, the results of which were correlated with fish consumption. Furthermore, a short study of mercury in nails was carried out and correlated to the results from hair mercury levels. A small quantity of 5 mg of hair with an addition of 50 μL of water to the sample without previous treatment was adequate to get a representative result in less than 10 minutes. The accuracy of the proposed method was confirmed by analysing certified reference materials including Coal Fly Ash-NIST SRM 1633b, Fucus-IAEA 140 and three unpolished Rice Flour NIES-10. The observed results were found to be in good agreement with the certified values.

Modification of a Reaction Vessel for the Determination of Total Mercury in Hair by Cold Vapor Atomic Absorption Spectrometry

A classical cold vapor atomic absorption spectrometric (CVAAS) method for the determination of total mercury in blood has been previously adapted for application to samples of human hair. The reaction vessel specified in the original adaptation was, however, large and difficult to use with small hair samples. In the present study, the reaction vessel has been modified and reduced in size and the protocols have been optimized in order to provide an analytical method that is more efficient, less time-consuming, and gives lower blank values than the original adaptation. The optimized method was validated by multiple, independent, replicated assays of certified reference hair samples, and the mean recovery obtained (98.7%) indicated an efficient performance of the digestion and detection processes. The method was applied to the assay of 144 hair samples derived from populations that had or had not been exposed to mercury from environmental sources. The results from all of the samples analyzed were consistent with those published previously for similar samples.

Prenatal and Early Childhood Exposure to Mercury and Methylmercury in Spain, a High-Fish-Consumer Country

Exposure to mercury, a risk factor for neurodevelopmental toxicity, was assessed in Spanish children (preschool children and newborns, n = 218) in a four-locations survey by performing mercury determination in hair. To assess the prenatal and children's exposure and its potential risk, total mercury (THg) and methylmercury (MeHg) were analyzed and examined for associations with maternal sociodemographic characteristics and dietary intake through interviews and food frequency questionnaires. The mean THg in hair was 0.94 microg/g, ranging from 0.19 to 5.63 microg/g in preschool children and 1.68 microg/g (0.13-8.43 microg/g) in newborns. Associations between mercury levels in hair and fish consumption frequency were found regardless of the group evaluated. Neither other food item nor maternal covariates were associated with mercury levels in the newborn group. In children, the mean THg values among frequent fish consumers (more than four times per week) were almost threefold higher compared with non-consumers (1.40 vs. 0.49 microg/g). Newborns from mothers who had intake of fish two or more times per week exhibited nearly threefold higher hair levels than those who rarely or never consumed fish (2.26 vs. 0.78 microg/g). Finally, mercury levels in hair exceeded the EPA reference dose (RfD) of 0.1 microg Hg/kg body weight per day (equivalent to 1 microg Hg/g hair) in 42% of the population studied. Overall, we conclude that levels of mercury in Spain are among the highest in the non-exposed populations probably because of the relatively high fish consumption.

Determination of Mercury in Hair by Square-Wave Anodic Stripping Voltammetry at a Rotating Gold Disk Electrode After Microwave Digestion

A simple and reliable method for the determination of mercury in hair on a rotating gold disk electrode using subtractive anodic stripping voltammetry without removal of oxygen is reported. Voltammetric and microwave parameters were optimized to obtain the best analytical results. Parameters such as supporting electrolyte concentration, influence of chloride in the Hg peak, deposition potential, scan rate, accumulation time, rotation rate, square-wave amplitude, and electrode conditioning were studied. Pressurized microwave-assisted digestion of hair, suitable for the accurate voltammetric determination of Hg, was evaluated using six acid mixtures and several time-power programs. Under the optimized conditions, no interference by copper, cadmium, lead, nickel, manganese, iron, or zinc was found at concentrations corresponding to their occurrence in normal hair. A calibration plot between 6,67 and 46,69 microg/L was linear, with r(2) better than 0.999. The detection limit for a deposition time of 60 s at 254 g was calculated as 1.92 nM (3omega). Validation of the method was demonstrated with the use of a certified reference sample of hair. Eight real samples of hair (four unexposed children and four exposed persons) were also analyzed.

Determination of mercury in hair by coupled CVAA-ICP-MS

This paper describes the coupling of a cold vapour atomic absorption (CVAA) instrument with an ICP-MS to obtain mercury concentration information and stable isotopic ratio data. The sample preparation procedure, based on microwave digestion, describes the decomposition of small masses of hair using 7 ml digestion vessels, which will enable the methodology to be used subsequently with neonatal hair samples. The results based on a CRM hair sample and spiked real samples indicated that the digestion method with direct CVAA analysis gave recoveries of around 100% with a corresponding RSD of 3.5%. The interfacing of the CVAA instrument to the ICP-MS was relatively simple and enabled isotopic data to be obtained in tandem with CVAA quantitative data. Some ICP-MS mercury memory problems were observed with the coupled CVAA-ICP-MS but these did not affect either the CVAA determination or isotopic ratio estimations.

Anodic stripping voltammetric determination of traces of mercury with a chemically modified electrode

A new method for the determination of traces of mercury(II) with a ferrocenoylpolythia crown ether—Nafion-modified glassy carbon electrode was developed. The modified electrode was formed by simply adding the desired amount of modification solution onto the glassy carbon electrode surface and drying in air. The mercury ion is accumulated on the modified electrode surface by the complexing effect of the modifier during the electrochemical deposition. After medium exchange, the accumulated mercury is determined by the anodic stripping voltammetric method. A linear response of the stripping peak current with concentration is observed for 3 × 10 −9 −8 × 10 −8 M of mercury(II) and the detection limit is 1 × 10 −9 M (5 min preconcentration period). High sensitivity is obtained owing to the complexing effect of the modifier and the release of the complexing reagent (modifier) from the mercury(II) complex during the electrochemical deposition. For 10 deposition/determination cycles (1 × 10 −8 M Hg(II)) the response could be reproduced with a 3.8% relative standard deviation. Many parameters such as the composition of the modification solution, concentration of electrolyte, electrodeposition potential etc., influence the response of the determination. The effect of coexisting ions has been examined. The procedure has been applied to the determination of mercury in hair, water, and urine samples.

Quantitative Determination of Mercury in Hair by Activation Analysis

Activation analysis was applied for quantitative determination of mercury in hair and the data obtained were compared with those by colorimetric method using dithizone. The analyses of the materials sampled from individuals residing in Japan and in other countries were performed and it was found that the non-destructive analysis is a desirable method for the purpose in giving accurate results even for the samples which are unsuitable for the colorimetic analysis because of the small contents of mercury, and especially when a lot of samples are to be analysed within a limited time. The distributions of mercury along the length of long hairs obtained from "Minamata diseased" patients and thir families in Niigata prefecture were determined by non-destructive method and interesting results were obtained.