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On the reliability of methods for the speciation of mercury based on chromatographic separation coupled to atomic spectrometric detection
Umeå University, Faculty of Science and Technology, Chemistry.
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis deals with the reliability of methods for the speciation of mercury in environmental and biological samples. Problems with speciation methods that couple chromatography to atomic spectrometric detection and how to overcome the problems are discussed. Analytical techniques primarily studied and evaluated are high performance liquid chromatography-cold vapour-atomic absorption spectrometry (HPLC-CV-AAS), HPLC-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS), capillary electrophoresis-ICP-MS (CE-ICP-MS) and gas chromatography-ICP-MS (GC-ICP-MS). Applying a multi-capillary approach increased the analyte amount injected into a CE-ICP-MS system and improved the overall sensitivity. A microconcentric nebulizer with a cyclone spray chamber was shown to improve the detection limits for mercury species 3-13 times in HPLC-ICP-MS and 11-19 times in CE-ICP-MS compared to a cross-flow nebulizer with a Scott spray chamber. To decrease the interference of water vapour in HPLC-CV-AAS a Nafion dryer tube was inserted between the CV-generation and the detector. Methyl mercury was however lost in the Nafion unless it was reduced to elemental mercury prior transport through the dryer tube.

During sample pre-treatment, incomplete extraction, losses and transformation (alkylation, dealkylation, oxidation and reduction) of mercury species can lead to significant errors (underestimation and overestimation) in the determination of the concentrations. Methods to detect and determine the degree of transformation as well as correct for errors caused by transformation are presented in the thesis. The preferable method use species-specific enriched stable isotope standards in combination with MS detection and a matrix based calculation scheme. This approach is very powerful as both the concentrations of the species as well as the degrees of transformation can be determined within each individual sample.

Place, publisher, year, edition, pages
2003. , 35 p.
Keyword [en]
Analytical chemistry, Mercury, speciation, hyphenated techniques, HPLC, CE, GC, CV-AAS, ICP-MS, species-specific enriched stable isotope
Keyword [sv]
Analytisk kemi
National Category
Analytical Chemistry
Research subject
Analytical Chemistry
Identifiers
URN: urn:nbn:se:umu:diva-111ISBN: 91-7305-429-1 (print)OAI: oai:DiVA.org:umu-111DiVA: diva2:140231
Public defence
2003-05-23, Umeå, 13:00 (English)
Available from: 2003-09-25 Created: 2003-09-25 Last updated: 2009-05-25Bibliographically approved
List of papers
1. Improving sensitivity for CE-ICP-MS using multicapillary parallel separation
Open this publication in new window or tab >>Improving sensitivity for CE-ICP-MS using multicapillary parallel separation
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1999 (English)In: Journal of Analytical Atomic Spectrometry, ISSN 0267-9477, Vol. 14, no 12, 1933-1935 p.Article in journal (Refereed) Published
Abstract [en]

A multicapillary, capillary electrophoresis inductively coupled plasma mass spectrometry interface is described. This interface allows for higher sample loading to improve the overall sensitivity and analyte detection limits without sacrificing the separation efficiencies. The results obtained with this parallel system are presented for a cross flow nebulizer. A comparison of single capillary electrophoresis for both DIHEN and cross flow nebulizers is presented.

Identifiers
urn:nbn:se:umu:diva-2291 (URN)10.1039/a906100b (DOI)
Available from: 2003-09-25 Created: 2003-09-25 Last updated: 2010-02-17Bibliographically approved
2. Determination of mercury species by capillary zone electrophoresis-inductively coupled plasma mass spectrometry: a comparison of two spray chamber–nebulizer combinations
Open this publication in new window or tab >>Determination of mercury species by capillary zone electrophoresis-inductively coupled plasma mass spectrometry: a comparison of two spray chamber–nebulizer combinations
2000 In: Analyst, Vol. 125, no 4, 705-710 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:umu:diva-2292 (URN)
Available from: 2003-09-25 Created: 2003-09-25Bibliographically approved
3. Flow injection-liquid chromatography-cold vapour atomic absorption spectrometry for rapid determination of methyl- and inorganic mercury
Open this publication in new window or tab >>Flow injection-liquid chromatography-cold vapour atomic absorption spectrometry for rapid determination of methyl- and inorganic mercury
2000 (English)In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 125, no 6, 1193-1197 p.Article in journal (Refereed) Published
Abstract [en]

A previously described system for determining low concentrations of mercury species in environmental samples using flow injection high-performance liquid chromatography cold vapour atomic absorption spectrometry (FI-HPLC-CVAAS) has been further developed with respect to time of analysis, long term signal stability, memory effects, detection limits, and environmental friendliness. Methyl and inorganic mercury were determined without pre-treatment in brackish water and in digested biological certified reference materials, DOLT-2 and TORT-2. Results were compared with those obtained by gas chromatography microwave-induced plasma atomic emission spectroscopy (GC-MIP-AES) using either butylation with a Grignard reagent or ethylation with sodium tetraethylborate. With the FI-HPLC-CVAAS system, absolute detection limits are 1.7 pg and 3.4 pg for methyl and inorganic mercury, respectively. Mercury species in a sample can be determined at the 0.4 ng l−1 level within 5 min. For lower concentrations the time for analysis has to be increased.

Place, publisher, year, edition, pages
RSC Publishing, 2000
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:umu:diva-2293 (URN)10.1039/B000933O (DOI)
Available from: 2003-09-25 Created: 2003-09-25 Last updated: 2012-06-27Bibliographically approved
4. Mercury species transformations during sample pre-treatment of biological tissues studied by HPLC-ICP-MS
Open this publication in new window or tab >>Mercury species transformations during sample pre-treatment of biological tissues studied by HPLC-ICP-MS
2002 (English)In: Journal of Analytical Atomic Spectrometry, ISSN 0267-9477, E-ISSN 1364-5544, Vol. 17, no 11, 1486-1491 p.Article in journal (Refereed) Published
Abstract [en]

A high-performance liquid chromatography (HPLC) system with a C18 column and an aqueous phase eluent (0.08% ammonium acetate and 0.02% L-cysteine) was directly connected to an inductively coupled plasma mass spectrometer (ICP-MS). HPLC-ICP-MS was used to study the abiotic formation of methylmercury, CH3Hg+, from inorganic mercury, Hg2+, as well as demethylation of CH3Hg+ to Hg2+ in biological tissues during treatment with tetramethylammonium hydroxide (TMAH) followed by pH adjustment with citric or acetic acid. Enriched isotope standards from CH3198Hg+ and 201Hg2+ were added to the samples to monitor species transformation and to apply species-specific isotope dilution (SSID) calibration. Depending on the type of sample matrix, up to 11.5% of added Hg2+ was methylated and up to 6.26% CH3Hg+ was demethylated to Hg2+. Methylation of Hg2+ probably takes place mainly during and after pH adjustment and it decreases after prolonged TMAH treatment. To minimize abiotic methylation, it is therefore recommended to proceed with pH adjustment after samples have been treated with TMAH for 24 h. There is no significant difference in the degree of methylation using citric or acetic acid.

Place, publisher, year, edition, pages
RSC Publishing, 2002
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-2294 (URN)10.1039/B205246F (DOI)
Available from: 2003-09-25 Created: 2003-09-25 Last updated: 2015-11-13Bibliographically approved
5. Determination of Methylmercury, Ethylmercury, and Inorganic Mercury in Mouse Tissues, Following Administration of Thimerosal, by Species-Specific Isotope Dilution GC-Inductively Coupled Plasma-MS
Open this publication in new window or tab >>Determination of Methylmercury, Ethylmercury, and Inorganic Mercury in Mouse Tissues, Following Administration of Thimerosal, by Species-Specific Isotope Dilution GC-Inductively Coupled Plasma-MS
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2003 (English)In: Analytical Chemistry, Vol. 75, no 16, 4120-4 p.Article in journal (Refereed) Published
Abstract [en]

Isotopically enriched HgO standards were used to synthesize CH3200Hg+ and C2H5199Hg+ using Grignard reagents. These species were employed for isotope dilution GC-ICPMS to study uptake and biotransformation of ethylmercury in mice treated with thimerosal, (sodium ethylmercurithiosalicylate) 10 mg L-1 in drinking water ad libitum for 1, 2.5, 6, or 14 days. Prior to analysis, samples were spiked with aqueous solutions of CH3200Hg+, C2H5199Hg+, and 201Hg2+ and then digested in 20% tetramethylammonium hydroxide and extracted at pH 9 with DDTC/toluene. Extracted mercury species were reacted with butylmagnesium chloride to form butylated derivatives. Absolute detection limits for CH3Hg+, C2H5Hg+, and Hg2+ were 0.4, 0.2, and 0.6 pg on the basis of 3 of five separate blanks. Up to 9% of the C2H5Hg+ was decomposed to Hg2+ during sample preparation, and it is therefore crucial to use a species-specific internal standard when determining ethylmercury. No demethylation, methylation, or ethylation during sample preparation was detected. The ethylmercury component of thimerosal was rapidly taken up in the organs of the mice (kidney, liver, and mesenterial lymph nodes), and concentrations of C2H5Hg+ as well as Hg2+ increased over the 14 days of thimerosal treatment. This shows that C2H5Hg+ in mice to a large degree is degraded to Hg2+. Increased concentrations of CH3Hg+ were also observed, which was found to be due to impurities in the thimerosal.

Identifiers
urn:nbn:se:umu:diva-9948 (URN)10.1021/ac0342370 (DOI)
Available from: 2008-05-29 Created: 2008-05-29 Last updated: 2017-10-24Bibliographically approved

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