G1 Advances in analytical methodologies

Thursday, 28 July, 2011

RG1-P1 — 11:00-12:00 and 17:30-18:30
Author: PURVES, William1
(1) Mercury One LTD, wpurves330@gmail.com

The analysis of mercury at the part per trillion level has become a challenge that most laboratories and field operations would like to avoid. At Mercury One part per trillion level analysis has become routine in the laboratory. Though analysis seems simple, sample preparation has become a major part of the challenge o9f generati8ng accurate data. The two methods that are currently utilized in the laboratory for the analysis of mercury have accuracy issues that are not fully understood by the average laboratory. The fluorescent process that is currently sited in each of the methods discussed in this paper is relatively accurate as long as samples are relatively clean.

However, 65% of the samples received at Mercury One do not fit this category. Method 1631E and 245.7 have unique digestion and purging processes that do not always generate accurate data. Poor data generation can directly affect treatment and removal of mercury from discharges. Modifications to the digestion and purging process in the current methods have been developed by Mercury One to help the laboratory generate more accurate data. These changes discussed in this paper have assisted in the development of a treatment system that is effectively reducing some difficult discharges from and average 5 ug/L discharge to less than 5 ng/L discharge.

Results and Conclusion:
One of the key components to determining accuracy when analyzing mercury samples is spiking and spike recoveries. Mercury One has the only ultra low level instrument that allows the analyst to see the mercury vapor evolve in real time. The evaluation of real time data as well as interference data has evolved into digestion and analysis procedures that work for 99% of the samples received by Mercury One. The results have also helped in the development of a very effective treatment system that is removing more than 99.9% of the mercury in a very difficult discharge. The real time evolution of the mercury vapor found issues with the discharge that were corrected by adjustments in the removal process that resulted in an effective treatment system removing mercury to less than 5 ng/L.

RG1-P2 — 11:00-12:00 and 17:30-18:30
Author: TATSY, Yury G.1
(1)Vernadsky Institute of Geochemistry and Analytical Chemistry, tatsy@geokhi.ru

Increased interest in the processes of transformation of mercury in the environment has led to a gradual shift from the routine determination of total mercury to speciation of this metal. Thermodesorption technique is well known as a qualitative method for determination the mercury species in solid environmental samples - soil, sediments, rocks, etc. For the first time this method has been applied in the beginning 60’s to study the regularities of formation of halos around mercury deposits. Currently it is used for geochemical prospecting, study of contaminated areas, research on the transformation of mercury and its compounds in the environment, study the thermochemical properties of compounds. Based on published and original data, as well as physical and chemical properties of mercury and its compounds, the attempt was made to interpret the thermodesorption curves obtained for samples of different nature and origin. The correctness of the interpretation of the thermospectra for real samples by comparison with the thermodesorption curves for pure compounds and minerals is discussed. The factors affecting the shape and characteristic parameters (time of appearance and end, temperature of the maximum) of the desorption peaks: heating mode (continuous vs. stepwise) and heating rate, type of carrier gas, grain-size, sample preparation (abrasion and sieving) and storage. The possibility of the quantitative assessment of various mercury species according to their thermospektra peaks is discussed also.

RG1-P3 — 11:00-12:00 and 17:30-18:30
Authors: PENA, Emilio J.1, FERNÁNDEZ-MARTÍNEZ, Rodolfo2, GALÁN, Pilar3, GÓMEZ-MANCEBO, Belén3, MATSUYAMA, Akito4, RUCANDIO, Isabel3
(1) Nicaraguan Research Center for Aquatic Resources of the National Automous University of Nicaragua, emilio.pena@cira-unan.edu.ni; (2) Unidad Espectroscopía, División Quimica / Dpto. Tecnología / CIEMAT, Madrid, Spain; (3) ; (4) National Institute for Minamata Disease, Minamata, Japón;

During the period of 1967-1992, there existed a Mercury-cell chlor alkali plant that produced chlorine and caustic soda, close to the shore of Lake Xolotlan, Managua City. During a period of 13 years (until 1982), the factory is estimated to have dumped about 40 tons of inorganic mercury into the Lake Xolotlan. Despite contamination of the Lake Xolotlan and the associated health risks, local communities and the population living on the coast of the lake are dependent on the lake resources for their livelihood and economic well-being.

Chlor alkali plants around the world still account for roughly 15% of global mercury demand, and are a significant source of local and global mercury pollution. In this work Hg mobility and availability were studied in soil samples collected nearby this lake. For this purpose a novel and specific five-step sequential extraction scheme was used. Mercury was then separated into the following operationally defined fractions: Labile Hg Species (0.5 M nitric acid extractable), humic and fulvic complexes (0.1 M sodium pyrophosphate extractable), mercury sorbed into amorphous Fe and Mn oxihydroxides (0.25 M hydroxilamine hydrochloride extractable), elemental mercury (50% v/v nitric acid extractable) and bound to sulphide mercury (0.03 M potassium iodide extractable). The total mercury concentrations varied between 1.0 and 7.1 mg.Kg-1. Fractionation measurements indicated elemental as the predominant mercury fraction followed by a humic and fulvic bound mercury fraction. Moreover, accumulation of elemental Hg in soils decreased with the increasing distance from the mercury emission source. The presence of elemental mercury in soils is important because it could be reemitted to the atmosphere by volatilization and even it has been established that bacteria transform this species into the more toxic methylated mercury compounds. Similarly, the strong positive correlation (R2 = 0.90) found between elemental and humic and fulvic complexes fractions suggests that a significant part of deposited mercury is complexed by soil organic matter. In conclusion, surrounding soils appear to be affected by mercury emissions from the plant.

RG1-P4 — 11:00-12:00 and 17:30-18:30
Authors: PFEIL, David1, MACALLISTER, Bruce1
(1) Teledyne Leeman Labs, dpfeil@teledyne.com

Co-operation on cosmetics regulation and control is of international importance. At the fourth annual meeting of the International Cooperation on Cosmetic Regulation1 (ICCR) mercury was recognized as one of three trace contaminants requiring framework documentation.

In the United States, the Food and Drug Administration (FDA) has authority over the marketing and distribution of cosmetics under the Federal Food, Drug and Cosmetic Act (FD&C). This act prohibits the interstate commerce of cosmetics that are either adulterated or mislabeled. One of several ways a cosmetic may be considered adulterated is if it "contains a poisonous or deleterious substance which may render it injurious to users under the conditions of use prescribed in the labeling thereof".

The toxicity of mercury compounds is well known. These compounds can produce allergic reactions, skin irritation and neurological disorder. As mercury can be absorbed through the skin and has a tendency to accumulate in the body over time, it clearly constitutes a deleterious substance. In the US most cosmetics with a mercury concentration of more than 1 ppm are regarded as adulterated. Specific products used around the area of the eye, such as mascara, with a mercury content above 65 ppm are deemed adulterated.

Last year the FDA published an alert1 which prohibited the import of adulterated creams from the Dominican Republic and Mexico without further inspection because they had been found to contain as much as 8% mercury.

One of the strongest advantages of the thermal decomposition technique is its ability to release mercury from a wide variety of matrices without any sample digestion. This ability enables the rapid analysis of cosmetics with very different matrices such as lipstick, makeup foundation, mascaras, creams and lotions.

In this presentation, we will provide data on the mercury content found in a variety of commercially available cosmetic products manufactured inside and outside the United States.

1 The International Cooperation on Cosmetic Regulation is a group of regulatory authorities from Canada, the European Union, Japan, and the United States.
2Import Alert #53-18 Detention without physical examination of skin whitening creams containing mercury.

RG1-P5 — 11:00-12:00 and 17:30-18:30
Authors: RYZHOV, Vladimir1, SHOLUPOV, Sergey E.1, POGAREV, Sergey E.2, MASHYANOV, Nikolay R.3
(1) Lumex Ltd, Hg@lumex.ru; (2) St.Petersburg State University; (3) St. Petersburg State University.

Three basic models of real-time monitors RA-915AM based on Zeeman atomic absorption spectroscopy have been developed for continuous monitoring of ambient air, natural, stack and process gases. Zeeman AAS enables direct analysis of mercury in a gas flow without pre-concentration step. This decreases unpredictable errors typical for trap analyzers due to traps aging and poisoning. Zeeman background correction coupled with a multi-path analytical cell with the effective length up to 10 meters provides unique combination of the low detection limit and high selectivity of analysis.

Optical cells with various optical lengths cover the full range of possible mercury concentrations in air and gases. The RA915?? monitors do not need any compressed gases and regular calibration; zero and span corrections are adjusted automatically using the built-in zero filter and calibration test cell with saturated mercury vapor. It extends the RA-915?? unattended operation up to six months. Statistical data show that the auto calibration function reduces the analytical error caused by the sensitivity drift down to 2% of the measured concentration. The errors emerged from the zero drift can be neglected if the zero drift correction period is selected properly. The method is fully compliant with new European standard EN 15852 - Ambient air quality - Standard method for the determination of total gaseous mercury. Examples of the RA-915AM applications for monitoring ambient air, natural and process gases are given.

RG1-P6 — 11:00-12:00 and 17:30-18:30
Authors: DÓREA, José1, BEZERRA, Vera Lucia V.A.2, FAJON, Vesna3, HORVAT, Milena3
(1) Universidade de Brasilia, dorea@rudah.com.br; (2) Universidade de Brasília; (3) Jožef Stefan Institute;

Depending on the stage of development of the CNS and the severity of insults a wide range of mental damage can result as a result of mercury exposure. The most controversial aspect of early post-natal exposure to organic mercury is as ethylmercury (EtHg) in Thimerosal-containing vaccines (TCV) still used in many countries. Thus nursing infants can be exposed to both fish derived methylmercury (MeHg) in maternal diets and to EtHg from TCV. The hair of infants (<12months) that had been exposed to TCV (Hepatitis B and DTaP) was analysed. A method coupling isothermal gas chromatography with cold-vapor atomic fluorescence spectrometry was used for MeHg which can also speciate EtHg in biological matrices. In 20 samples of infants’ hair, all but two samples showed variable amounts of MeHg (10.3 to 668 ng g-1), while precise and reliable concentrations of EtHg (3.7 to 65.0 ng g-1) were found in 15 of the 20 samples. A statistically significant inverse association (r= -05572; p=0.0384) was found between hair-EtHg concentrations and the time elapsed after the last TCV vaccination. The analytical method proved sensitive enough to quantify EtHg in babies’ hair after acute exposure to thimerosal in vaccine shots. Provided that the mass of hair was above 10 mg, both forms of organic Hg can be monitored in hair from breastfed infants: chronic exposure to MeHg from human milk and acute EtHg exposure as a result of inoculation with TCV. Thus, babies’ first hair can be used for clinical and forensic studies.

RG1-P7 — 11:00-12:00 and 17:30-18:30
Authors: POGAREV, Sergey1, RYZHOV, Vladimir2, SHOLUPOV, Sergey2, MASHYANOV, Nikolay1, PITIRIMOV, Pavel1, SENICHENKOV, Vasily2
(1) St. Petersburg State University, Hg@lumex.ru; (2) Lumex;

Recent trends in mercury analysis give rise to the expanding use of direct sample combustion (pyrolysis) without its preliminary treatment, which supersedes the cold vapour (CV) technique even in analyses of such complex-matrix samples as foodstuff, crude oil, biological materials, etc. The direct combustion technique rules out rather complicated and time-consuming sample pretreatment that is necessarily involved in the CV method. This also eliminates analytical errors specific to wet digestion and other steps of sample preparation for CV analyses, improves the detection limit, and increases the analysis throughput.

A set of the Zeeman mercury spectrometer RA-915+ and PYRO-915 attachment was used to optimize the pyrolysis technique for analyses of solid and liquid samples, such as soil, marine sediments, coal, biological materials, foodstuff, plastics and resins, medicine and cosmetics, water and water solutions, crude oil, naphtha, etc.

The PYRO-915 attachment is specially designed for analysis of complex-matrix samples. In its double-section atomizer, the temperature inside the first section (evaporator) is programmable in a range of 100 – 800 OC, and the temperature inside the second section (catalytic converter) and analytical cell is maintained at 700 OC. For example, it was ascertained that the temperature of the analytical cell should be above 500 OC to provide correct analysis of crude oil. At a lower temperature, the measurement error may be as large as 100%. A higher cell temperature above 650 – 700 OC is necessary to prevent mercury recombination with active radicals, such as chlorine, whereby accurate analysis of samples with a high content of halogens is ensured.

Special temperature conditions were implemented for highly contaminated samples with the mercury concentration up to 500 ppm. Our comprehensive study of the combustion behavior and selective--nonselective absorption ratio provides optimal temperature conditions to be specified for pyrolysis of various complex-matrix samples.

RG1-P8 — 11:00-12:00 and 17:30-18:30
Authors: HAMMERSCHMIDT, Chad R.1, BOWMAN, Katlin L.1, TABATCHNICK, Melissa D.1, LAMBORG, Carl H.2
(1)Wright State University, chad.hammerschmidt@wright.edu; (2) Woods Hole Oceanographic Institution.

Accurate determinations of trace levels of mercury (Hg) in water require scrupulously clean sampling equipment and storage bottles. To avoid Hg contamination during storage, it has been presumed that water samples must be stored in either glass or Teflon® bottles cleaned with a rigorous method, such as submersion in hot concentrated acid. Such cleaning procedures are hazardous and time consuming, and the use of Teflon® as a bottle material can be cost prohibitive for major oceanographic programs. We investigated the suitability of alternative cleaning procedures and bottle materials for storage of seawater containing sub-picomolar levels of Hg. We found that a simple cleaning technique with detergent, dilute acid, and bromine monochloride removes Hg from all bottle materials tested, which included FEP Teflon®, glass, polycarbonate, low-density polyethylene (LDPE), and fluorinated polyethylene (FLPE). The stability of seawater Hg levels differed dramatically among storage bottle materials during a 74-week test. Hg in seawater stored in LDPE, FLPE, and FEP bottles was increased significantly within 15 weeks of storage at room temperature. In contrast, seawater Hg levels were unchanged in glass and polycarbonate bottles throughout the test. Contamination of seawater stored in FEP bottles, presumably by diffusion of elemental Hg, calls into question the accuracy of Hg determinations made on low-Hg samples stored in this material for extended periods under these conditions. We recommend future use of this new cleaning method and encourage greater utilization of glass and polycarbonate bottles for storage of waters containing low levels of Hg.

RG1-P9 — 11:00-12:00 and 17:30-18:30
Authors: BOWMAN, Katlin L.1, HAMMERSCHMIDT, Chad R.1
(1) Wright State University, bowman.49@wright.edu

Humans are exposed to toxic monomethylmercury (MMHg) principally by the consumption of marine fish. However, and due in part to analytical limitations, little is known about the distribution, sources, and biogeochemical cycling of MMHg in the ocean, where aqueous concentrations are in the femtomolar range and often less than current limits of detection. Here, we present a simple method for extraction and analysis of MMHg in seawater that has a detection limit of about 2 fM for a 2-L sample, which is a 10-fold improvement over current approaches. The technique, which is readily adaptable to a shipboard laboratory, involves purging and quantification of dimethylmercury (DMHg) from an unaltered 2-L water sample followed by acidification to 1% with H2SO4 for > 6 h, pH neutralization, derivatization of MMHg in the seawater matrix with an ethylating agent, and purge-and-trap analysis with gas-chromatographic cold-vapor atomic fluorescence spectrometry. The method was developed and validated with analyses of seawater from the North Atlantic and Pacific Oceans, in addition to two fresh waters. This technique can be used to quantify, differentiate, and develop an improved understanding of the biogeochemistries of MMHg and DMHg in the ocean.

RG1-P10 — 11:00-12:00 and 17:30-18:30
Authors: TAGUCHI, Masashi1, KAGOSHIMA, Hiritada2, WATANABE, Tomoaki3, HASEGAWA, Ryo4, TOYOGUCHI, Toshiyuki4, TANIDA, Koji3
(1)Nippom Instruments Corporation, tagu-nic@rigaku.co.jp; (2) Nippon Instruments Corportion; (3) Nippon Instruments Corporation; (4) Environmental Control Center Co.,Ltd;

Regulations regarding heavy metal contamination in industrial products are becoming more stricter than before in the world (1). In particular, EU (European Union) has been applying various regulations to poisonous chemicals contained in industrial products. ELV (End of Life Vehicles) Directives(July, 2003), RoHS (Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment) Directives(July, 2006) including RoHS Directives for Japan and China, and REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) Regulations are included in those regulations.

Of those regulated substances, mercury is regarded as one of the specified toxic materials of the strict control targets and must be controlled by the industrial manufacturers. Then, in addition to the accuracy of the analysis, the measurement of mercury should be done desirably by simple, safe and rapid procedures for multiple samples. The reduction-cold vapor atomic absorption spectrophotometric method which requires the wet pretreatment has been adopted as the official method in many countries. On the other hand, the thermal decomposition (gold amalgamation) method has been discussed as an alternative official analytical method for RoHS Directive–related substances due to its freedom from interfering substances and dangerous reagents and its high sensitivity.

In this paper, the principle, operational easiness and actual measurement examples of the thermal decomposition (gold amalgamation) method and its instrumentation will be explained. Our method was applied to the following industrial products; fluorocarbon polymers, fluorocarbon polymers, circuit boards, various electronic parts, fluorescent tubes, ceramics, polyester and polyethylenes. The accuracy and reliability of the present method was confirmed by measuring polyethylene standard materials and copper ore. Our method was proved to be a candidate for the officially approved IEC62321 methodology.

(?) Masashi Taguchi?KCS-JAIMA?Joint Symposium?Abstract,?P4,?Korea,?30,Apr.?2010)

RG1-P11 — 11:00-12:00 and 17:30-18:30
Authors: SHOLUPOV, Sergey E.1, POGAREV, Sergey E.2, RYZHOV, Vladimir V.1
(1) Lumex Ltd., SholupovSE@lumex.ru; (2) St.Petersburg State University, Russia;

Zeeman atomic absorption spectrometry (ZAAS) is a differential technique whereby two beams with different wavelengths are produced. Radiation of one beam is absorbed by mercury atoms and subjected to the background absorption. Radiation of the second beam is subjected only to the background absorption since the wavelength of the beam is shifted and located outside the absorption line envelope of mercury atoms. The difference in wavelengths between the two beams is very small and most constituents absorb radiation of the both beams in the same way. However, there are few kinds of molecules which have absorption bands with partially resolved rotational-vibrational structures and, as a result, different beams are absorbed by these molecules in different way. Under definite conditions, the presence of such kind of molecules can bring about analytical errors. Examples of spectroscopic interferences of SO2, NOx, O3, H2S, benzene (C6H6)and other compounds are discussed in the presentation.

In ZAAS with the direct Zeeman effect, measurement results depend on relative positions of the Zeeman emission components and envelope of absorption mercury line. Therefore, a change in shape of the absorption envelope, e.g., because of a change in pressure of a gaseous sample, can give rise to analytical errors. It is shown in the presentation that a variation in pressure of a gaseous sample in the range 1.0 - 0.4 bar gives an analytical error not exceeding 5%. Therefore, when mercury is determined in ambient air at different heights, the effect of pressure on the analytical result can be neglected up to a height of 7km.

RG1-P12 — 11:00-12:00 and 17:30-18:30
Authors: DARBY, Steven B1, SMITH, Paul D2, VENABLES, Dean S.1
(1) University College Cork, s.darby@umail.ucc.ie; (2) now at King’s College London;

The outstanding questions of atmospheric mercury chemistry have renewed interest in alternative analytical methods to measuring mercury. Current instruments do not give detailed information on speciation or fluxes in the atmosphere and there is a need to improve on existing technologies to make instruments for atmospheric Hg detection faster, cheaper and more sensitive. Here we present a novel approach based on cavity enhanced absorption spectroscopy (CEAS). Even in a relatively small instrument, the highly reflective mirrors of optical cavities can increase the pathlength of light through the sample to hundreds of metres, thereby greatly improving the absorption sensitivity. Pathlengths far in excess of traditional Herriot or White multipass cells are possible. Although lasers are conventionally used in CEAS systems, an innovation of our CEAS instrument is to use an Hg lamp as the light source and avoid the expense and complexity of deep-UV laser systems. We analyse the sensitivity of the device and discuss potential applications of the approach.

RG1-P13 — 11:00-12:00 and 17:30-18:30
Authors: PITIRIMOV, Pavel V.1, SHOLUPOV, Sergey E.2, POGAREV, Sergey E.3, RYZHOV, Vladimir V.2
(1) St. Petersburg State University, p.p@list.ru; (2) Lumex Ltd; (3) St.Petersburg State University;

Presently, the analytical task of mercury monitoring of industrial and waste water is rather vital. On-line mercury determination in such water is complicated by the presence of dissolved compounds at high concentration, e.g., industrial water of some coal-fired power plants contains about 3% of chlorides and sulfates. Sample pretreatment steps are necessary for total mercury determination using conventional CV (cold vapor) technique. Field experience of such kind shows that capillaries used as sampling line are very often get clogged by precipitated salts. Therefore, mercury monitors based on the CV technique are unsuitable for long unattended operation since they call for frequent maintenance. An alternative technique for mercury atomization, namely, thermal destruction of samples (pyrolisys) can be used in a water mercury monitor. One of the problems of the pyrolisys technique is the presence of dissolved compounds at high concentration. Being evaporated in the oven, the dissolved compounds are converted to fine particles, aerosols and vapor, and then are transported by a carrier gas into the analytical cell where they cause certain spectroscopic interference in AA measurements and partially precipitate on the windows. Therefore, the final detection technique should be highly selective relative to such kind of interferences.

As a final detection technique, the Zeeman AAS meets these requirements. In a monitor considered here, a sample is injected in the oven continuously through a nebulizer. Programmably, distilled water and calibration solution are injected in the system to perform the zero test and check the calibration coefficient. To reduce interferences of chlorides, the cell is maintained at a temperature higher than 650 OC. The contamination of the windows is reduced due to a special design of the cell. Thus, the mercury detection limit lower than 1 ug/l has been obtained at a response time shorter than 20 s for industrial water with a high salt background (up to 3%).

RG1-P14 — 11:00-12:00 and 17:30-18:30
Authors: KODAMATANI, Hitoshi1, MATSUYAMA, Akito2, KONO, Yuriko1, KANZAKI, Ryo1, SAITO, Keiitsu3, TOMIYASU, Takashi1
(1) Kagoshima University, kodama@sci.kagoshima-u.ac.jp; (2) National Institute for Minamata Disease; (3) Kobe University;

This study developed a simple and sensitive high-performance liquid chromatography (HPLC) method for determination of methylmercury, which is based on formation of complexes of mercury species, mercury ions, methylmercury, ethylmercury, and phenylmercury through the use of the emetine dithiocarbamate (emetine-CS2) ligand; it involves HPLC separation and a chemiluminescence reaction of tris(2,2’-bipyridine)ruthenium(III) with emetine-CS2 ligand. The calibration graphs of these four complexes were linear in the range 0.05–5.0 µg/L at an injection volume of 200 µL. The developed HPLC method was validated by comparing its results with certified reference materials of methylmercury, CRM7402-a (cod fish, NMIJ), CE464 (tuna fish, ERM), CRM No.13 (human hair, NIES), and CC580 (estuarine sediment, ERM). Sample solutions for injection into the HPLC system were prepared as follows. Mercury species were eluted with 5-M HCl solution from these reference materials and then extracted with dichloromethane as emetine-CS2 complexes after neutralized and adjusted to approximately pH 5. A portion of the dichloromethane phase was evaporated to dryness and the residue was dissolved in a 20-mM borate buffer (pH 9.1)-acetonitrile (50:50, v/v) solution. The results agreed well with the certified values, except for the case of CC580. As CC580 contains a high concentration of mercury ions, the peak of methylmercury overlapped with the large peak of mercury ions. Therefore, a selective extraction method for methylmercury in soil and sediment samples was also developed. Methylmercury was extracted with toluene as methylmercury chloride from 5-M HCl solution and then back-extracted with 2-mM EDTA solution. Complexation reactions of the mercury species and emetine-CS2 ligand occurred upon addition of emetine-CS2 solution to a portion of the EDTA solution. This method facilitated detection of methylmercury from the solution having mercury ions in high concentration (<100 mg/L), via the proposed HPLC method. However, the matrix compounds in soil and sediment prevented extraction and/or back-extraction of methylmercury in real-sample analysis. Therefore, various masking reagents for matrix compounds were considered. Then, a 5-M HCl solution containing 0.1-M Cu2+ and 1-mM Pd2+ was used as the extraction solution from soil and sediment samples. The result obtained using the developed extraction method was in good agreement with the certified value of CC580.

RG1-P15 — 11:00-12:00 and 17:30-18:30
Authors: BOGANS, Egils1, SVAGERE, Anda1, SKUDRA, Janis1, GAVARE, Zanda1, POIKANE, Rita2
(1) Institute of Atomic Physics and Spectroscopy, University of Latvia, egils.bogans@gmail.com; (2) Latvian Institute of Aquatic Ecology.

There are many common objects that contain mercury, for instance, mercury lamps, switches and mercury thermometers. Though EU regulations target minimization of mercury use, there are still a number of such objects in circulation. When disposed, they usually are thrown into trashcans and afterwards transported to the waste dump. From there mercury makes its way into environment increasing mercury pollution. The first step on a way to stop this increase is gathering the data about mercury presence at waste dump sites to allow for informed decisions about necessary further actions.

Judging from the results of previous surveys (e.g., [1]), disposed trash is one of the mercury pollution sources in Latvia. The aim of this study is to evaluate usability of Zeeman atomic absorption spectrometer RA-915+ for monitoring of mercury concentrations in different types of samples at waste dump sites. Mercury pollution surveys at several corresponding locations were performed, analyzing air, water and soil samples.

Mercury concentration in the air was measured in real-time, using capability of RA-915+ analyzer to make direct measurements. For mercury concentration determination in water samples, the analyzer together with RP-91 attachment was used; the principle of operation is based on could vapor atomic absorption spectroscopy – CV-AAS. Mercury determination in soil was performed, decomposing samples and atomizing contained mercury in pyrolitic furnace attachment RP-91C.

Results of surveys show that Zeeman atomic absorption spectrometer complemented with necessary attachments can be a versatile tool for determination of mercury in various sorts of samples. Elevated mercury concentrations were found in some, but not all samples.

[1] Z. Gavare, E. Bogans, A. Skudra, A. Svagere, Mercury pollution surveys in Riga (Latvia), Abstracts of 11th Workshop on Progress in Analytical Methodologies for Trace Metal Speciation, Munster, Germany, Sept. 4 – 7 (2007) 78.

The work was partially supported by ESF project “Spectrometric techniques for detection of heavy metal contaminants” (Nr. 2009/0210/1DP/ and by EC FP7-ENV-2010 project “GMOS” (Agr.#265113).

RG1-P16 — 11:00-12:00 and 17:30-18:30
Authors: ALI, Arif1, , Pratima2, ASAD, Shahzada2
(1) Department of Biotechnology, Jamia Millia Islamia University, ali.arifali@gmail.com; (2) Jamia Millia Islamia University;

Adequate supply of fresh and clean drinking water is a basic need for every form of life on the earth. But due to urbanization, the most horrible crises of water pollution with heavy metals has arisen because of various anthropogenic activities. Although some metals are essential trace elements, most can be, at high concentration are toxic to all forms of life including microbes.

Microorganisms particularly bacteria found in polluted water bodies and landfills have evolved the resistance mechanism against heavy metal toxicity by efflux, complexation or reduction of metal ions. The present study has been carried out to exploit this resistance mechanism for rapid detection of mercuric ions. To study the detoxification mechanism and to construct bacterial sensor for detection of mercury ions, 84 isolates of E. coli were collected from different aquatic environments of six geographically distinct regions of India, out of which 79% showed significantly high level of tolerance to inorganic mercury i.e., mercuric chloride (HgCl2). Growth curve studies in presence of mercury clearly indicated the presence of inducible mer operon in selected E. coli strains. Further, amplification of regulatory and transferase genes (merR-op-T) was accomplished and their sequence analysis revealed the divergence in these genes in different isolates. Development of bacterial sensor for detection of bioavailable mercury contamination in water bodies is achieved by insertion of these (merR-op-T) genes in front of promoterless lux structural genes (luxCDABE) from photobacterium (Vibrio fischeri) responsible for production of bioluminescence in order to transcribe lux genes using mer operator and promoter. Water samples were collected from different geographical locations of India and their mercury assessment was done. On assessment, Yamuna river sample showed 3.8 ppb of mercuric ions, in Hindon river sample, the concentration was found to be 1.2 ppb, Hooghly river sample had 0.52 ppb, where Yamuna river water system shows median and average values of total mercury concentration several times higher than the 1ppb recommended by WHO. Thus, the bacterial sensor developed here shows its potential in evaluating inorganic mercury concentration in various water bodies at much reduced cost and in lesser time.

RG1-P17 — 11:00-12:00 and 17:30-18:30
Authors: CORNS, Warren T1, STOCKWELL, Peter B1
(1) P S Analytical, wtc@psanalytical.com

Knowledge of the mercury content in petrochemicals is extremely important. Firstly, mercury is highly toxic and is of environmental concern and secondly, the damage caused to petrochemical plants can be financially crippling especially when unscheduled shutdowns are forced. Mercury has been found to be responsible for many cases of selective hydrogenation catalyst deactivation. Palladium based catalysts are commonly used for the selective hydrogenation of alkynes in the steam cracking of C2 to C4 cuts. Mercury is known to be the cause of corrosion problems with alumina based heat exchangers, rotors and condensers at natural gas refinery plants. Heat exchanger replacement is a costly operation due to the capital investment of the exchanger itself and the plant down time incurred for its replacement. This paper describes how atomic fluorescence spectrometry (AFS) can be applied to the measurement of mercury in petrochemical samples such as natural gas, LPG, LNG, naphtha and condensates. Typically these measurements are performed using offline laboratory techniques which are highly dependent on the sampling protocols utilized and the sample storage method. This is especially problematic for volatile forms of Hg which are easily lost from the sample. We have recently developed online process analyzers for both liquid and gaseous petrochemical streams. These are typically used in conjunction with mercury removal technologies so that the efficiency can be monitored in real time thus protecting expensive downstream apparatus. The performance characteristics of the analyzers will be discussed with reference to sampling, calibration, accuracy, precision and long term reliability.

RG1-P18 — 11:00-12:00 and 17:30-18:30
Authors: CORNS, Warren T1, ROGERS, Tony1, BROWN, Richard2, BROWN, Andrew2
(1)P S Analytical, wtc@psanalytical.com; (2) National Physical Laboratory;

The determination of TGM in ambient air and natural gas is analytically challenging because of the low concentrations encountered. In both cases sub ng/m3 detection limits are required to monitor accurate trends. The most commonly used technique is amalgamation – AFS with the calibration being performed by injection of air saturated with Hg vapour at ambient temperature. Whilst this a well proven convenient calibration approach small microliter injection volumes are required to allow mercury mass equivalent absolute calibrations in the range of the samples even when relatively large sample volumes are used. The uncertainty of measurement increases dramatically when the lowest portion of the calibration relationship is used which is often the case for measurements of TGM. In addition to this the analytical performance of gold traps at low ng/m3 concentrations may not be the same as injecting a small quantity of air saturated with Hg vapour at mg/m3 concentrations. This is more evident when gold traps become passivated over time and when two traps give widely different results. The extent of passivation is often unknown and accepting the highest result is analytically flawed because there is a strong possibility that several traps are giving low recoveries to different extents.

A more valid approach to calibration can be achieved using continuous flow dynamic Hg vapour generators operated in the ng/m3 range. Two approaches will be presented and compared. The first approach was based on the two fold dilution of saturated source of mercury at a controlled temperature. Mass flow controllers are used to generate the initial flows and the concentration generated is in the ug/m3. The second dilution was achieved using a critical orifice and eductor pump arrangement. The main advantage of this setup was the rapid stabilization time. The second approach was based a specially fabricated temperature controlled Hg permeation tube with mass flow controllers. The accuracy and precision data generated from both devices when coupled to a PSA amalgamation AFS will be presented. Both calibration devices were found to offer an excellent solution to calibrating fully automated TGM instrumentation.

RG1-P19 — 11:00-12:00 and 17:30-18:30
Authors: LEOPOLD, Kerstin1, ZIERHUT, Anja D. 2, ABDUL-JABBAR, Heven2, SCHLEMMER, Gerhard3, LABATZKE, Thomas3
(1) University of Ulm / Technical University Munich, kerstin.leopold@ch.tum.de; (2) Technical University of Munich; (3) Analytik Jena AG, Germany;

Mercury (Hg) is ubiquitous in the environment and requires analytical determination in all environmental compartments due to its high mobility and toxicity. In particular a comprehensive monitoring of mercury in the hydrosphere is important due to very high bioaccumulation factors of up to 106 times in fish and sea food. Therefore, fast and inexpensive methods for routine analysis of mercury in waters are essential. However, in standard measuring procedures for total dissolved mercury toxic reagents are normally used that produce hazardous waste. Omitting hazardous substances in the analysis procedure is an important contribution to a more sustainable and green analytical chemistry. At the same time it is cost-effective, provides easy handling and ensures low risk of contamination.

Therefore, a reagent-free method for ultra trace mercury determination (pg to ng L-1) in water samples has been developed recently [1]. An active nanogold collector provides preconcentration of Hg-species in a flow injection analysis system. After rinsing and drying of the collector, the enriched mercury is thermally desorbed and finally measured by atomic fluorescence spectrometry. Matrix interferences were studied and the method was optimized and validated for the determination of mercury in different natural waters. Accuracy and precision of the method were demonstrated by several recovery experiments in natural waters (recoveries: 96-104 %) and by analysis of certified reference materials BCR-578 (Mercury in Coastal Sea Water; recovery: 100.1 ± 5.3 %) and ORMS-4 (Elevated Mercury in River Water, recovery: 101.4 ± 11.6 %). With a detection limit of only 80 pg Hg L-1 the method is highly sensitive. This proposed method was now set-up as a prototype instrument consisting of a fully automated PC controlled flow injection analysis system for preconcentration of Hg traces coupled to an atomic fluorescence spectrometer for Hg detection. The prototype has been developed in a cooperation project between the Technical University of Munich and the Analytik Jena AG, Germany.

[1] A. Zierhut et al. (2010) Analysis of total dissolved mercury in waters after on-line preconcentration on an active gold column. Talanta 81:1529–1535.

RG1-P20 — 11:00-12:00 and 17:30-18:30
Authors: CHEN, Bin1, CORNS, Warren T1, STOCKWELL, Peter B1
(1) P S Analytical, bc@psanalytical.com

Urine is one of the most widely used ‘non-invasive’ biomarkers for risk assessment of mercury exposure. The sample pre-treatment procedure for urine analysis usually involves simple dilution with deionised water or diluted acid, its validity is generally supported by the analytical results of freeze-dried urine reference material. In real samples, however, the spike recoveries were found to be largely dependent of the individual urine matrix, despite the excellent recovery obtained for the reference material. The interference caused by the organic matter in the urine samples is far from negligible. In this work, several sample pre-treatment procedures have been investigated for total mercury and mercury speciation in urine samples, followed by the detection of atomic fluorescence spectrometry. The challenge of mercury speciation using HPLC lies in the poor separation of Hg(II) and methylmercury peaks when 2-mercaptanethanol was (most commonly) used as modifier. In this work, a newly developed mobile phase based on APDC modifier provides clear baseline separation for mercury species within 15 minutes, followed by the online UV digestion and HPLC-CV-AFS. The accuracy and precisions of the procedures were not only validated by the reference materials, also by the spike recoveries of inorganic and methylmercury in almost every urine samples analysed.

RG1-P21 — 11:00-12:00 and 17:30-18:30
Authors: CLARKE, David1, MCQUATTERS, John1, FORSBERG, Jeff1
(1) Cetac Technologies, dclarke@cetac.com

Mercury compounds are permitted by the U.S. Food and Drug Administration for use in eye makeup at concentrations up to 65 parts per million and are permitted only if no other effective and safe preservative is available for use. Other cosmetics may contain trace amounts of mercury containing mercury less than 1 part per million (0.0001 percent), because the presence of trace mercury is unavoidable even under conditions of good manufacturing practice. Cosmetics with mercury content above these levels are considered to be adulterated and subject to regulatory action [21 CFR 700.13]. On a state level, Minnesota on Jan 1st, 2008 enacted a law banning intentionally added mercury in mascaras, eyeliners and skin-lightening creams. These requirements lead to a need for measuring trace amounts of mercury within a complex sample matrix.

A method for the determination of trace amounts of mercury in cosmetics is reported. The method involved acid treatment of the samples on a block digester and analysis by cold vapor generation-atomic absorption (CVAA) detection. Cosmetics (~0.20 g) were subjected to digestion with 2 ml H2SO4 and 2 mL HNO3 and subsequently KMnO4. The solution was diluted to 50 mL with 3% HCl, well mixed and filtered. The sample was reduced with a 7% SnCl2-10% HCl solution and then passed to a gas-liquid separator where the evolving Hg(0) was swept in a stream of Ar to the detector cell and the atomic-absorbance signal was recorded. The data from these widely used cosmetic products showed mercury levels in the low parts per billion and parts per trillion ranges, well below the 1 part per million regulatory cutoff.

RG1-P22 — 11:00-12:00 and 17:30-18:30
Authors: LEOPOLD, Kerstin1, HUBER, Jessica 2, ZIERHUT, Anja D. 3
(1) University of Ulm / Technical University Munich, kerstin.leopold@ch.tum.de; (2) Technical University of Munich; (3) Technical University Munich.

We recently developed a flow injection analysis system coupled to atomic fluorescence spectrometry (AFS) for the quantification of total dissolved Hg from waters [1]. For the preconcentration of Hg species a nano-structured gold surface was generated from smooth gold surfaces by adsorbing and thermally desorbing elemental mercury (Hg0). Smooth gold surfaces selectively trap only Hg0 via an amalgamation process, whereas nano-structured, catalytically active gold surfaces adsorb all dissolved mercury species. In both cases release of mercury can be achieved by thermal desorption. These procedures can be used as preconcentration steps in analytical methods for total Hg determination or Hg speciation in waters, respectively. However, an online regeneration step for selective collectors has to be worked out that enables smoothening of roughened surfaces in-between the measuring cycles.

A smooth gold surface (selective collector) is regained from a nano-structured surface by re-orientation of gold atoms within 14 days at room temperature [2]. In order to recreate a smooth and selective surface within minutes different procedures and treatments of the gold surfaces were tested. The gold collector was exposed to various reagents (HCl, H2O2, ascorbic acid) irradiated with ultraviolet light (λ = 254 nm). Thereby free radicals (·OH, ·OOH) of high standard reduction potential are formed and react with the active sites of a nano-structured gold surface. The adsorption rates of different mercury species onto the manipulated gold surfaces were measured by AFS. Changes of the surface structure were characterized by atomic force microscopy. A comparison of these data for all performed experiments will be presented and conclusions will be drawn. The results prove that chemical polishing of gold surfaces is possible with the proposed procedures. Hence, this method is a promising tool for the online regeneration of smooth gold surfaces, i.e. selective gold collectors.

[1] A. Zierhut et al., Talanta 81 (2010) 1529-1535.
[2] A. Zierhut et al., J. Anal. At. Spectrom. 24 (2009) 767-774.

RG1-P23 — 11:00-12:00 and 17:30-18:30
Authors: PYHTILÄ, Heidi H1, PERÄMÄKI, Paavo2, PIISPANEN, Juha3, NIEMELÄ, Matti2, SUORANTA, Terhi2, STARR, Mike4, NIEMINEN, Tiina3, KANTOLA, Marjatta3, UKONMAANAHO, Liisa3
(1) Finnish Forest Research Institute, University of Oulu, heidi.pyhtila@metla.fi; (2) University of Oulu; (3) Finnish Forest Research Institute; (4) University of Helsinki;

The aim of this study was to determine total mercury (Hg) concentrations directly from natural water samples using cold vapor inductively coupled plasma mass spectrometry (CV-ICP-MS). Sampling was performed in eight drained peatland forest catchments located in eastern Finland. Six of the catchments had been harvested using whole-tree harvesting (including removal of stumps) or stem-only harvesting method. Water samples were collected from ditches in each area. In addition, peat water samples were collected from pools of standing water, which had formed after stump lifting.

In the method studied, Hg was not preconcentrated and the analyses were performed from non-filtered water samples to avoid the possible contamination and analyte losses during filtration. Samples were preserved and oxidized with bromine monochloride (BrCl) solution to convert all Hg species into ionic form (Hg2+). In the CV-ICP-MS method the sample is mixed on-line with a reducing agent (SnCl2) subsequently transforming Hg2+ to volatile Hg0 that is carried using argon flow to the plasma and detected by mass spectrometer.

Samples analyzed in this study contained significant amounts of dissolved organic matter (10 - 100 mg DOC L-1) which is known to interact strongly with Hg. The organic matter was observed to have an effect on the oxidation efficiency of BrCl in the sample pretreatment step and on the analyte signal during measurements. The causes of matrix effects were investigated to understand better the behavior of Hg in our samples. Based on our results, the CV-ICP-MS method appears to be suitable for determining low Hg concentrations directly from natural water samples.

RG1-P24 — 11:00-12:00 and 17:30-18:30
(1) INRS-ETE, Université du Québec, benbarst@hotmail.com; (2) Department of Earth and Environmental Sciences, Wright State University; (3) Department of Biology, Texas Christian University; (4) Department of Biological Sciences & Institute of Applied Science, University of North Texas; (5) Department of Obstetrics and Gynecology, Medical University of South Carolina, Hollings Marine Laboratory;

Mercury is found in the environment in elemental, inorganic, and organic forms. Methylmercury, the predominant organic form, compromises the majority of mercury in fish muscle tissue (≥90%). For this reason total mercury analysis is often substituted for the more time consuming and expensive methylmercury analysis in fish muscle, while mercury speciation is reserved for analysis of organs like the liver. The percentage of methylmercury in fish liver is more variable and could be dependent on species-specific physiology. Past research from our laboratory and others has linked hepatic damage in fish with elevated hepatic inorganic mercury concentrations. Knowledge of methylmercury and inorganic mercury concentrations is therefore essential when studying hepatic mercury toxicity in fish. Here, we present a quick and relatively inexpensive method for inorganic mercury determination in fish liver. This method involves microwave acid digestion, removal of the methylmercury from the acid (with toluene) and analysis of inorganic mercury in a diluted aliquot of the acid by Direct Mercury Analyzer (DMA-80). We have demonstrated good reproducibility and recovery of inorganic mercury. Methylmercury can also be analyzed by DMA-80, after it is transferred from toluene to an aqueous phase (L-cysteine solution), but recovery is low (<70%). Instead, methylmercury concentrations can be calculated by subtracting the determined inorganic fraction from total mercury in the same sample. We are currently validating the method by comparison with accepted techniques (GC-CVAFS and Thiourea Complex IC-CVAFS).

RG1-P25 — 11:00-12:00 and 17:30-18:30
Authors: FERNÁNDEZ-GÓMEZ, Cristal1, HINTELMANN, Holger2, BAYONA, Josep M.1, DÍEZ, Sergi1
(1) Institute of Environmental Assessment and Water Research (IDAEA-CSIC), cfgqam@cid.csic.es; (2) Trent University;

The Diffusive Gradients in Thin films (DGT) technique is an operationally defined method to determine the dissolved fraction of trace elements in water. The aim of this study was to develop this technique for the measurement of the bioavailable mercury (Hg) species in natural waters. For that purpose, three types of DGT units (commercial (C-DGT), manufactured with agarose diffusive gel (A-DGT) and manufactured with polyacrylamide diffusive gel (P-DGT)) were tested under controlled conditions using an Hg2+ solution both with and without dissolved organic carbon (DOC). An acid digestion method using Aqua Regia was optimized to efficiently digest the resin gel discs prior to dual stage gold preconcentration and CVAFS determination. A good performance was obtained for the three DGT types when deployed in a DOC-free Hg solution in the laboratory, and it was demonstrated that polyacrylamide gel does not accumulate Hg so it can be used as diffusive layer for Hg sampling. When the DGT units were deployed in an Hg solution containing DOC, logically the diffusion coefficient of the Hg species in the diffusive layer decreased one order of magnitude for the three DGT types, but also the performance of the C-DGT type deteriorated significantly. Furthermore, the mass of background Hg (blanks) in the commercial device was much higher compared to the in-house manufactured units. In the light of these results, the C-DGT samplers were discarded and the P-DGT devices seemed to be the best choice for dissolved Hg determination, since they provided the best correlation between the amount of Hg accumulated in the resin and the deployment time (R2 = 0.990 and R2 = 0.994, with and without DOC respectively), and its resin blanks were the lowest. However, if handling very low Hg concentrations in water, the A-DGT units might be better suited due to its slightly higher uptake rate.

RG1-P26 — 11:00-12:00 and 17:30-18:30
Authors: RUCANDIO, Isabel1, FERNÁNDEZ-MARTÍNEZ, Rodolfo2, GÓMEZ PINILLA, Isabel3, BORLAF, Fernando2, GARCÍA, Fernando 2, LARREA, M. T.4
(1) Unidad de Espectroscopía / División de Química / Dpto. Tecnología / Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), Av.Complutense 22 28040Madrid, Spain, isabel.rucandio@ciemat.es; (2) ; (3) Centro de Espectrometría Atómica. Universidad Complutense de Madrid; (4) Departamento de Metalurgia Física, Centro Nacional de Investigaciones Metalurgicas. CSIC. Avda. Gregorio del Amo, 8. 28040. Madrid. Spain.

In recent decades, there has been an incredible increase in direct consumption of seaweed as food in Western countries, partly because of the nutritional and therapeutic benefits these products provide. Seaweeds, as processed and unprocessed food, have a commercial value of several billion dollars annually. Approximately 500 species are eaten by humans, and some 160 are commercially important. In addition to the use of algal extracts in prepared foods, seaweeds are eaten directly in many parts of the world. The ability of marine seaweeds to effectively retain mercury as well as other heavy metals is well known. It has been suggested that seaweeds could absorb mercury from seawater and even from the atmosphere.

In this work total mercury contents were determined in several commercially available seaweeds. Ten different seaweeds were purchased from the market as dried material or pellets. In addition BCR 279 (Sea Lettuce) was used as reference material. Four different acid digestion systems were subject of comparison: (i) digestion in stainless steel-PTFE bombs at high pressure and temperature (PAR), (ii) at high temperature and atmospheric pressure in PFA closed vessels (SAV), (iii) in open vessels using a graphite heating block at high temperature (DP) and (iv) microwave assisted digestion in closed vessels (MW). All digestions were carried out with nitric acid. Determination of mercury in digested solutions was made by cold vapour atomic fluorescence spectrometry. Assessment of digestion methods was performed by comparison with the results obtained by direct mercury analysis using thermal decomposition, amalgamation and atomic absorption spectrometry. Among the different procedures, the best mercury recoveries were achieved with the DP digestion system.

RG1-P27 — 11:00-12:00 and 17:30-18:30
Author: URBA, Andrius1
(1) Research Center for Physical Sciences and Technology, Institute of Physics, urba@ktl.mii.lt

Although the elemental gaseous mercury (GEM) is believed to usually build up to at least of 95% of the atmospheric total gaseous mercury, the minor fractions of reactive inorganic (RAM) and volatile organic mercury species are of crucial importance because of their reactivity, toxicity and biological availability. Online and portable quantitative differentiating of these species appears to be state-of-the-art task up to this date.

The conventional method of KCl denuders for RAM detection has got both advantages and disadvantages, however, it has not got any considerable, yet online and portable alternative chemical method which could enable a quantitative intercomparison for RAM detection between different chemical methods on-line and on-site up to date. The alternative method to conventional KCl techniques for the detection of RAM will be suggested and disclosed here.

Even more state-of-the–art task seems to be the detection of gaseous organic mercury species in ambient air with the online and portable method. Providing the detection of gaseous organic mercury in addition to RAM and gaseous elemental (GEM), we can draw near to the important task of detection of the real total gaseous mercury (TGM) in ambient air. The insights and suggestions towards creation of such method will be disclosed here.

RG1-P28 — 11:00-12:00 and 17:30-18:30
Authors: LIENEMANN, Charles-Philippe1, BAUDOT, Arnaud1
(1) IFP Energies nouvelles, charles.lienemann@ifpen.fr

Diversification of feedstock supply in the petroleum industry due to barrel prices has resulted in the increased use of natural gas condensates. The latter contain mercury (10-5000 ppb) among others metals, which is blamed for poisoning catalysts and corroding aluminum alloys in steam cracker cold boxes in refinery, but could be also released to the environment. The prerequisite of risk assessment is the accurate measurement of mercury content and speciation in order to propose an efficient removal procedure.

Today, cold vapour atomic absorption spectrometry (CVAAS) and atomic fluorescence spectrometry (AFS) are the main technique used to determine total concentration. Different equipment are used within IFP Energies nouvelles in order to fulfil the need of analyses for real samples and pilot plant experiments.

ICP-MS is also used by coupling ICP-MS with gas (GC) or liquid chromatography (HPLC) in order to obtain an insight into the molecular weight distribution of mercury in various petroleum cuts.

The different approach used for total analysis will be discussed and compared based on the various need of the petroleum industry, but also of our research institute. The different information obtained from speciation will also be discussed and compare to conventional approach already described in the literature.

RG1-P29 — 11:00-12:00 and 17:30-18:30
Authors: PEDRERO ZAYAS, Zoyne1, MOUNICOU, Sandra1, MONPERRUS, Mathilde1, AMOUROUX, David1

In this work Hg stable isotopically labeled species were used to assist the investigation of Hg species (i.e. IHg and MeHg) binding biomolecules in the aqueous soluble fraction of white-sided dolphin (Lagenorhynchus acutus) liver homogenate (QC04LH4). Little is known about the bioaccumulation and metabolism of mercury in marine mammals. It has been suggested that Hg can bind thiol containing proteins/biomolecules. However most of the speciation studies are restricted to the discrimination between IHg and MeHg and carried out in the fish muscle due to its human consumption.

The aim of this study was to develop an analytical method to determine Hg species (i.e. IHg and MeHg) binding biomolecules in the liver sample. The partition of mercury species into the different tissue fractions revealed that MeHg is mainly found in the cytoplasm, and 80% of IHg is present in the solid residue.

The screening by size exclusion chromatography-ICP-MS analysis of the water-soluble fraction revealed the association of Hg with biomolecules in a wide molecular weight range. The analysis by GC-ICP-MS of the different size exclusion chromatography fractions has shown different ratios of IHg and MeHg. The cytosol was incubated with Hg isotopically labelled species isotopes, demonstrating an unambiguous specific affinity of the different biomolecules by IHg and MeHg.

RG1-P30 — 11:00-12:00 and 17:30-18:30
Authors: GILMOUR, Cynthia1, MAIZEL, Andrew1, RIEDEL, Georgia S.1
(1) Smithsonian Environmental Research Center, gilmourc@si.edu

We present a method for extraction, pre-concentration and detection of sub-ppt levels of Hg2+ and MeHg+ in environmental waters and sediment extracts. This method combines existing techniques to directly quantify inorganic Hg2+ and MeHg+ at environmentally relevant concentrations. It can also be paired with species-specific isotope dilution to calculate methylation and demethylation rates in many matrices. One goal in developing this method is to improve species-specific assays of demethylation rates, which are often measured by loss of MeHg, Direct measurement of both substrate and product would be preferable.

In order to measure changes in enriched Hg and MeHg isotopes in sediments by HPLC-ICP-MS, Hg species must first be efficiently extracted from the matrix and brought a into solution that can be loaded on an HPLC column. We are developing a method to do so using acidic HCl/NaCl/thiol closed-vessel microwave extraction. Thiol complexes are used to aid extraction, and to create Hg and MeHg-thiol species that can be separated on a hydrophobic HPLC column. The choice of thiol counter-ligand is critical. Goals in choosing a ligand include extraction efficiency from the sample matrix, good separation in reasonable run length by HPLC, and elution of the MeHg-thiol complex before the Hg-dithiol complex. The latter is important since Hg concentrations can be 10-100 or more times higher than MeHg in many sediments and soils, and MeHg peaks are difficult to quantify on the tail of a large inorganic Hg peak. Mercaptobenzothiazole is a promising ligand that yields neutrally charged Hg complexes which separate well on C-8.

Some preconcentration can be achieved by using a large volume sample loop and preloading a short C-8 column. The pre-concentration column is eluted onto the separation column with 5% isopropanol/0.05% mercaptobenzothiazole /0.05M acetate buffer/94.5% water. Finally, Hg and MeHg in column eluent are reduced and converted to the gas phase prior to direct gas injection into the ICP torch. Gas-phase analysis improves detection limits (DLs) over liquid analysis by 1-2 orders of magnitude. Reduction is accomplished using borohydride flow injection, followed by a gas-liquid separator.

With an absolute instrument DL of ~0.1pg (PE ELAN DRC II), this approach gives a method DL of ~10 pg/L of MeHg+ and Hg+ when a 10 mL sample in introduced. Methylation and demethylation processes that occur during the microwave extraction process can be monitored and corrected-for through the use of species-specific isotope dilution.

RG1-P31 — 11:00-12:00 and 17:30-18:30
Authors: ZIERHUT, Anja D1, STOIBER, Monika1, HARWARDT, Lena1, LEOPOLD, Kerstin2
(1) Technical University of Munich, anja.zierhut@ch.tum.de; (2) University of Ulm/ Technical University of Munich.

For mercury analysis in natural water samples, mercury has to be reduced to elemental mercury. Tin chloride (SnCl2) is commonly used for this purpose. In our studies different reducing agents have been tested for their efficiency in reducing dissolved naturally occurring mercury species to elemental mercury. The investigations were made in regard to the application for a species selective enrichment of elemental mercury onto gold-columns directly from the aqueous sample. In a recently developed system this direct adsorption was used for preconcentration of dissolved mercury, i.e. without cold vapour generation. Subsequent quantification was performed after thermal desorption by atomic fluorescence spectrometry [1].

We found that by using SnCl2, tin is alloyed on the gold surface. This gold/tin alloy adsorbs Hg0 from the liquid sample but no release of Hg is achieved by thermal desorption. Therefore, either the formation of the Au/Sn alloy has to be avoided by adequate rinsing of the column, e.g. by ethylenediaminetetraacetic acid, or a non-metallic reductant is to be used. We compared the reduction efficiency of sodium borohydride, hydroxylamine, formaldehyde, sodium formate, ascorbic- and formic acid towards inorganic Hg2+-species with the reduction efficiency of tin chloride. Furthermore, the behaviour and stability of organic mercury compounds towards these different reducing agents were tested and matrix interferences, e.g. the influence of dissolved organic carbon, were studied.

All tested non-metallic reductants that form gaseous by-products significantly reduce the adsorption efficiency (10-45%) on the gold surface. Furthermore, the gaseous by-products quench the fluorescence intensity causing a decrease in sensitivity. When using ascorbic acid and hydroxylamine the reduction efficiency depends on the concentration of the reductant. A complete reduction is achieved with 1-5 % (w/w) hydroxylamine or 2.5-5 % (w/w) ascorbic acid, respectively.

[1] A. Zierhut; K. Leopold; L. Harwardt; P. Worsfold; M. Schuster, J. Anal. At. Spectrom. 24 (2009) 767.

RG1-P32 — 11:00-12:00 and 17:30-18:30
Authors: CARTER, Annie1, UM, MiSun1, NELSON, Brittany1
(1) Brooks Rand Labs, annie@brooksrand.com

Mercury is a well-known human health hazard and is routinely monitored in public health studies in order to assess its effects on health outcomes. Total mercury is frequently measured to assess human exposure due to the relative ease of analysis; however, this information does not always provide sufficient information to accurately assess the source of exposure and/or risk to a person or community. Methylmercury biomonitoring is of greater value in predicting health outcomes due to the fact that it is more bioaccumulative and has more serious neurological effects than inorganic mercury. Because there is no definitive correlation factor establishing the ratio of methylmercury to total mercury in biological samples, it is important to measure methylmercury in human biomonitoring studies. Minimally invasive sample collection is desirable in most instances; therefore, human blood, urine, and hair are typically collected for analysis. Hair is particularly valuable, as it provides an exposure timeline, rather than an instantaneous snapshots of body burden provided by blood or urine analytical results. The digestion techniques routinely employed for the determination of methylmercury in hair are often subject to matrix interferences. In this study, we critically investigated digestion procedures for the analysis of methylmercury in hair samples.

Two digestion methods were compared: 25% potassium hydroxide in methanol and 4.57 M nitric acid. Both methods are based on procedures described in the peer-reviewed literature and were assessed for accuracy, reliability, and ease of preparation. After digestion, all samples were analyzed following EPA Method 1630 (CV-GC-AFS). The potassium hydroxide/methanol digestion method exhibited significant matrix interference, as demonstrated by the recoveries of matrix spikes and certified reference materials. The causes of this interference were investigated. The nitric acid digestion method did not exhibit a substantial level of matrix interference, and excellent recoveries were achieved for matrix spikes and reference materials.

RG1-P33 — 11:00-12:00 and 17:30-18:30
Authors: LASORSA, Brenda1, GILL, Gary2, FLETT, Robert J.3, HINTELMANN, Holger4
(1) Battelle Marine Sciences Laboratory, brenda.lasorsa@pnl.gov; (2) attelle Marine Sciences Laboratory; (3) Flett Research Ltd.; (4) Trent University.

The Penobscot River and Estuary is presently the focus of a large multidisciplinary ecosystem study to investigate mercury contamination released over several decades from a now defunct chlor-alkali facility. The project has a rigorous QA/QC program, including analytical intercomparison studies which revealed a large discrepancy in sediment monomethylmercury (MMHg) concentrations between the distillation method (Horvat, et al., 1993) and the extraction technique (Bloom, et al, 1997) for sample preparation. When the laboratories conducted measurements based on distillation for the preparation of sediment samples, they recovered significantly more MMHg. This discrepancy was limited to field samples; it was not seen in any of the Quality Control samples (SRMs, blank spikes, matrix spikes, etc.). Initially, it was assumed that the discrepancy was due to the inorganic mercury methylation artifact previously described by Bloom et al. (1997) in which sediments with high concentrations of inorganic mercury formed MMHg during the distillation process. This hypothesis was subsequently not supported based on tests using species-specific stable mercury isotope additions to monitor for production of MMHg. To examine the nature and extent of the difference, approximately 200 sediment samples collected along the entire length of the river were analyzed by both methods. A subset of samples was also analyzed by a third method using KOH/Methanol digestion. All sample distillates, extracts or digestions were analyzed by aqueous-phase ethylation followed by cold vapor atomic fluorescence detection. The samples prepared by distillation recovered an average of 2.13 times that recovered by extraction (n=184) with a correlation (r2) of 0.92. The discrepancy range was 0.94 to 4.75. The samples collected in downstream end of the study area tended to have a larger discrepancy between the preparation methods than the samples collected in the upstream collection areas. The data for samples analyzed by the KOH/Methanol digestion correlated more closely with the extraction preparation technique than with distillation. Our current working hypotheses to explain this discrepancy are that the extraction method is not capable of isolating specific forms of MMHg (i.e. bound in specific substrates) leading to under-recovery of the available MMHg present in the sediment by this method or that there is an artifact that cannot accurately be quantified with traditional isotopic labeling methods.

RG1-P34 — 11:00-12:00 and 17:30-18:30
Author: VASSILEVA, Emiliya1
(1) IAEA, e.vasileva-veleva@iaea.org

Determination of mercury content in the low ng kg-1 range remains a fundamental analytical challenge and a great source of complexity for the realisation of reliable profiles of dissolved mercury. Although the detection sensitivity of ICP-MS allows the direct measurement of mercury at sub-ng g-1 levels the physical deposition of salts on interface cones and polyatomic interference from the major ions in environmental matrices does not allow a simple analysis. Therefore, sample pre-treatment or matrix elimination prior to sample introduction into the plasma was often inevitable. The present investigation represents comparative study of several approaches based on preliminary separation and preconcentration of mercury followed by High Resolution Isotope Dilution Inductively Coupled Mass Spectroscopy (HR ID-ICP-MS) of Atomic Fluorescence Spectrometry (AFS) determination. Could Vapour ID-ICP-MS and Could Vapour AFS methods featuring gaseous introduction of mercury via tin chloride reduction have been developed and applied in the first analytical approach. Second approach is based on matrix separation and preconcentration of mercury on chelate resin with the direct APEX sample introduction. To achieve SI-traceable values with small combined uncertainties of mercury amount contents in seawater measurement procedures, according to sound metrological principles, were developed. The measurement method in the first case was based on direct isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS) applied as a primary method of measurement. The correct assessment of the analytical procedural blank was of the crucial importance for obtaining reliable results. In order to achieve the lowest possible procedural blank, all sample-processing steps were accomplished in a class-100 clean chemical laboratory and class 10 ultra clean fume hood. The estimation of the total uncertainty associated to each measurement result was fundamental tool for sorting the main sources of measurement biases. Preliminary forecast of the uncertainty budgets was used as a strategy to ensure that determination in mercury in seawater could be achieved with demonstrated traceability to a stated system of reference within less than 3% expanded uncertainty (k=2). The results for the determination of mercury by using three independent methods showed an excellent agreement.

RG1-P35 — 11:00-12:00 and 17:30-18:30
Authors: VASILEVA, Emiliya1, OH, Jae1, BETTI, Maria1, AZEMARD, Sabile1
(1) IAEA, e.vasileva-veleva@iaea.org

Determination of mercury content in the low ng kg-1 range remains a fundamental analytical challenge and a great source of complexity for the realisation of reliable profiles of dissolved mercury.

Although the detection sensitivity of ICP-MS allows the direct measurement of mercury at sub-ng g-1 levels the physical deposition of salts on interface cones and polyatomic interference from the major ions in environmental matrices does not allow a simple analysis. Therefore, sample pre-treatment or matrix elimination prior to sample introduction into the plasma was often inevitable.

The present investigation represents comparative study of two approaches based on preliminary separation and preconcentration of mercury followed by High Resolution Isotope Dilution Inductively Coupled Mass Spectroscopy (HR ID-ICP-MS) determination. Could Vapour ID-ICP-MS method featuring gaseous introduction of mercury via tin chloride reduction have been developed and applied in the first analytical method. Second approach is based on matrix separation and preconcentration of mercury on chelate resin with the direct APEX sample introduction.

To achieve SI-traceable values with small combined uncertainties of mercury amount contents in seawater measurement procedures, according to sound metrological principles, were developed. The measurement method in both cases was based on direct isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS) applied as a primary method of measurement. The correct assessment of the analytical procedural blank was of the crucial importance for obtaining reliable results. In order to achieve the lowest possible procedural blank, all sample-processing steps were accomplished in a class-100 clean chemical laboratory and class 10 ultra clean fume hood.

The estimation of the total uncertainty associated to each measurement result was fundamental tool for sorting the main sources of measurement biases. Preliminary forecast of the uncertainty budgets was used as a strategy to ensure that determination in mercury in seawater could be achieved with demonstrated traceability to a stated system of reference within less than 3 % expanded uncertainty (k=2).

The results for the determination of mercury by using two independent methods showed a degree of agreement 0.2%.

RG1-P36 — 11:00-12:00 and 17:30-18:30
Author: JACOBSEN, Lindsay1
(1)Miletone Inc., mercury2011@agendamanagers.com

Direct Mercury Analysis is a well-established technique for determining mercury in a wide range of sample matrices. Compared to more traditional techniques for mercury analysis (i.e.; CVAA and ICP-MS), direct mercury analysis requires no sample preparation, generates no sample waste, and has a short turnaround. One challenge with direct mercury analysis was that samples with very low mercury concentration were difficult to analyze without first pre-concentrating the system by running several samples. Recently, Milestone introduced Tri-Cell technology into their direct mercury analyzer, the DMA-80. This technology allows samples with low levels of mercury to be analyzed in a single run, opening up the possibility to carry out previously unachievable applications including low-level Hg work in naphtha, groundwater, and oil. Tri-Cell technology further increases the analytical range to include both high and ultra-trace mercury concentrations in the same instrument. This presentation will discuss this new technology and specifically present new applications.

RG1-P37 — 11:00-12:00 and 17:30-18:30
Authors: STOTESBURY, Theresa E. 1, VREUGDENHIL, Andrew J.1, HINTELMANN, Holger H.1, BILLARD, Christophe2
(1)Trent University Chemistry Department; (2) Universite de Reims laboratoire de Pharacognosie Groups de Glycotechine.

A novel diffusive gradient thin film material (DGT) has been synthesized using inorganic-organic sol-gel materials and was optimized for inorganic mercury uptake. The DGT is a three component system made from convenient water-borne silane precursors including an adhesive epoxy surface treatment, a thiol functionalized resin and a starch modified diffusive layer. Device fabrication does not require heating and allows large scale production with a relatively long shelf life compared to other DGT devices. The new resin and diffusive layer were characterized using Raman spectroscopy, scanning electron microscopy (SEM) and BET surface area analysis. The thickness of the diffusive layer was determined with SEM and is approximately 1.3 µm. Mercury uptake performance was determined by atomic fluorescence spectroscopy (AFS). The resin’s uptake exceeds 9 ng cm-2 after 26 hours of deployment. Preliminary performance tests demonstrate that analyte uptake is in accordance to Fick’s first law of diffusion, which permits the direct determination of total mercury concentration. The diffusion coefficient of inorganic mercury in the sol-gel diffusive layer is 5 x 10-6 cm2s-1. This technique has significant potential as an alternative in situ sampling methods for inorganic mercury and presumably methylmercury.

Thursday, 28 July, 2011