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Measuring Bioavailable Copper in Estuarine Waters using an Ion Exchange ResinSnyder, Jeffrey D. 02 November 1999 (has links)
Anion exchange methods were used to measure the percent of weakly bound and strongly bound copper in estuarine waters and agricultural drainage. Copper bound to an ion exchange resin has been operationally defined as bioavailable copper, or copper that is available for uptake by aquatic organisms.
Initial laboratory testing indicated that the percent of copper bound to the resin did not differ between a freshwater solution (pH 6.5 buffered with 30 mg/L as calcium carbonate) and a saline solution (25 ppth salinity at pH 8). Adding 20 mg/L natural organic matter (NOM) to each solution lowered the amount of copper sorbed to the resin by the same amount in saline and fresh water. Varying salinity from 16 to 30 ppth did not effect % bioavailability. This indicates that the ions typically found in seawater do not compete with copper for ion exchange onto the resin. Varying initial copper concentration from 195 to 495 ppb for the given NOM content of 12.5 mg/L did not effect % bioavailability, indicating that as the copper concentration of this water is increased over the range studied, the fraction of potentially toxic copper is constant.
Decreasing the pH of the system from 8.5 to 4 and the NOM from 12.5 to 0 mg/L statistically increased % bioavailability in both cases. However, copper retention onto the resin at pH values near 4 was hindered, possibly because resin functional groups become inefficient at low pH values. MINEQL+ predicted that the resin was not retaining approximately 30% Cu<sup>+2</sup> at a pH of 4. Copper retention to the resin was also not as high as expected at NOM contents between 0 and 3 mg/L at pH 8.1. MINEQL+ indicated that the water studied at pH 8.1 was comprised primarily of strongly bound copper-organic ligand species and Cu(OH)<sub>2</sub>. Experimental results suggested that the resin retained only 50% Cu(OH)<sub>2</sub>, which is a potentially bioavailable copper complex. However, MINEQL+ computer modeling indicated that the resin was accurately retaining potentially bioavailable copper in waters with a pH from 5.5 to 8.5, containing 3 to 12.5 mg/L NOM.
After assessing the characteristics of copper retention by the resin, it was applied to an estuarine system and agricultural drainage to measure bioavailable copper. The results indicated that in copper-containing agricultural runoff and groundwater the percent bioavailable copper was approximately 15% of the dissolved copper. This percentage was relatively constant over the range of copper concentrations observed. In estuarine systems receiving agricultural runoff, the percent bioavailable copper was about 11%.
This research was supported by a grant from the Virginia Pesticide Control Board. / Master of Science
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Stanovení mikroprvků v mléce pomocí ICP-OES po extrakci technikou DGT / Determination of microelements by ICP-OES after extraction by DGT techniqueHabartová, Aneta January 2020 (has links)
This thesis is focused on determination of microelements (Cd, Co, Cu, Fe, Mn, Ni, Pb a Zn) in milk by optical emission spectrometry with inductively coupled plasma (ICP-OES) after extraction by Diffusion Gradients in Thin films technique (DGT) containing Chelex 100 resin gel and agarose diffusion gel. The optimalization of DGT in model metal solutions was verified by recommended basic tests. The performance of the DGT technique in the diluted milk matrix was verified. By DGT technique was determined only Zn in real milk matrix with concentration 3,74 ± 0,02 mg/l. The other microelements in the prepared eluate were at or below the limit of detection of the instrumental method. The obtained results were compared with the analysis of milk after microwave digestion by ICP-OES. However, these results were below the detection limit of the device too, only Zn with concentration 3,91 ± 0,16 mg/l was measured. For the future analysis of the selected microelements in milk by DGT technique, further optimization of the preconcentration technique is required, or use of a more sensitive instrumental method.
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Avaliação da resina quelante chelex-100® na pré-concentração e da espectrometria de absorção atômica de alta resolução com fonte contínua e forno de grafite para a determinação de metais-traço em água produzida de alta salinidadeFreire, Aline Soares 14 April 2016 (has links)
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Dissertação - Aline Soares Freire - FINAL.pdf: 4503064 bytes, checksum: 1e469a75225eda50cf3c49c6ab32c87a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geociências-Geoquímica. Niterói, RJ / A análise de amostras hipersalinas ainda é um problema analítico a ser resolvido,
tendo em vista que a presença de sais dissolvidos é fonte freqüente de
interferências em espectrometria atômica. Atualmente, tem ocorrido um grande
aumento da demanda para caracterização de águas de alta salinidade, como as
águas produzidas, pelo fato de estas serem um dos maiores descartes da indústria
de petróleo. Devido a isto, metodologias analíticas para sua caracterização têm sido
amplamente desenvolvidas para a determinação de metais-traço em amostras
salinas e dentre as técnicas analíticas destaca-se a Espectrometria de Absorção
Atômica de Alta Resolução com Fonte Contínua, uma renovação da AAS
convencional. Contudo, para a obtenção de resultados acurados, é imprescindível
que se faça a remoção dos sais presentes nessas matrizes hipersalinas. Essa
separação prévia pode ser realizada através do emprego de resinas qualantes, que
pré-concentram o analito e permitem a remoção da matriz. Sendo assim, este
trabalho visa à avaliação do uso da resina quelante comercial Chelex-100® na préconcentração
de Co, Cu, Mn, Ni e Pb e posterior determinação destes por
Espectrometria de Absorção Atômica de Alta Resolução com Fonte Contínua e
Forno de Grafite (HR-CS GF AAS). A metodologia foi validada através do uso dos
materiais de referência certificados para água do mar CASS-4, CASS-5 e NASS-5.
Os limites de detecção obtidos, em μg L-1, foram de 0,006; 0,070; 0,024; 0,074; e
0,018 para Co, Cu, Mn, Ni e Pb, respectivamente. Amostras de água produzida
oriundas de plataformas de petróleo offshore foram analisadas e os resultados
mostraram que essas águas possuem baixas concentrações dos elementos
determinados ou os mesmos não foram detectados. Os valores encontrados são
muito inferiores aos limites preconizados pela legislação brasileira através da
Resolução CONAMA 357/05 / The analysis of hypersaline samples is still an analytical problem to be solved, once
the presence of dissolved salts is a frequent source of interferences in atomic
spectrometry. Actually, there is a large increase in the interest in the caracterization
of this kind of sample, as produced waters are one of the largest discharges of
petroleum industry. Hence, analytical methodologies to produced water
caracterization have been widely developed to trace metals determination in saline
samples and among the analytical techniques, there is High Resolution Continuum
Source Atomic Absorption Spectrometry, a renovation of conventional AAS.
However, to obtain accurated results, it's necessary to remove the salts present in
this high salinity matrices. This previous separation can be done employing a
chelating resin, that preconcentrates the analyte(s) and allows matrix removal. In this
way, the aim this work is to evaluate the use of chelating resin Chelex-100® to
preconcentrate Co, Cu, Mn, Ni and Pb, for the later determination by High Resolution
Continuum Source Graphite Furnace Atomic Absorption Spectrometry (HR-CS GF
AAS). The methodology was validated by the use of sewater certified reference
materials CASS-4, CASS-5 e NASS-5. The detection limits in μg L-1, were 0,006;
0,070; 0,024; 0,074; and 0,018 for Co, Cu, Mn, Ni and Pb, respectively. Produced
water samples from offshore petroleum platforms were analysed and results showed
that this waters have low concentrations of these studied elements or could not be
detected. Found values are much lower when compared to limits from Brazilian
legislation, in this case CONAMA 357/05 Resolution
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UTVÄRDERING AV DNA-EXTRAKTIONSPROTOKOLL FÖR FORENSISKA PROVERAwad, Kassem January 2019 (has links)
Vid låga mängder av DNA, vilket det ofta är vid forensiska prover, är en lyckad DNA-analys beroende av ett effektivt DNA-extraktionsprotokoll. Bland flera kommersiellt tillgängliga extraktionsmetoder för DNA har tidigare studier visat att Chelex 100 resin, som idag används på Nationellt Forensiskt Centrum i Linköping, är en snabb och enkel metod utan toxiska ämnen, långa väntetider eller större kostnader och som även ger ett högt DNA-utbyte. På teknisk mikrobiologi i Lund har olika chelex-baserade protokoll för spårsäkring och extraktion tagits fram för att optimera det aktuella protokollet på Nationellt Forensiskt Centrum. I detta arbete kombinerades spårsäkringsteknik och DNA-extraktionsprotokoll från tidigare studier med olika rör och tops, med syftet att i bästa fall generera ett protokoll som är optimalt för de vanligast förekommande brottsplatsproverna. I resultatet observerades högre DNA-utbyte med reducerade volymer lyseringsbuffert, vilket användning av rör-i-rörsystem tillät. När rör-i-rörsystem sedan kombinerades med extraktionsprotokoll innehållande SDS, observerades en ökning i DNA-utbytet. När dessa två faktorer vidare kombinerades med en tops vars skaft kan klippas rakt av ökade DNA-utbytet ytterligare. Ett byte från mikrofugrör, som används på Nationellt Forensiskt Centrum idag, till ett rör-i-rörsystem reducerar lyseringsvolymen från ca. 600 µl till 200 µl vilket är en avgörande faktor för effektivare extraktioner. / When handling low amounts of DNA, which often is the case with forensic samples, a successful DNA analysis is dependent on an effective DNA extraction protocol. Among many commercially available extraction methods for DNA, previous research has proved Chelex 100 resin, which is used at National Forensic Center in Linkoping, to be a quick and simple method without toxic substances, long waiting time or large costs, which in addition provides a high DNA exchange. At Applied Microbiology, Lund´s University, different chelex-based protocols for sampling and DNA extraction have been developed to optimize the present protocol at the National Forensic Center. In this study, sampling techniques and DNA extraction from previous studies was further combined with different tubes and swabs with the aim to, in best case, generate a protocol that is optimal for the most common crime scene samples. The results showed improved DNA yields with less extraction volume, which the tube in tube system made possible. When tube in tube system was combined with extraction protocols containing SDS, a higher DNA yield was observed. When these two factors were further combined with a cotton swab, whose shaft can be cut straight of, the DNA yield improved even more. A change from microfuge tubes, which is used at the National Forensic Center, to tube in tube system, the lysis volume could be reduced from approximately 600 µl to 200 µl which is a deciding factor for higher DNA yield.
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The production of 103Pd and 109Cd using proton irradiated tandem natAg/natAg targetsIneza, Claire 03 1900 (has links)
103Pd is an important therapeutic radionuclide and has recently found great interest due to its higher radiobiologic effect. 109Cd decays by electron capture and is generally used as calibration sources in industrial and medical fields. A new method for the production of 103Pd and 109Cd using the 66 MeV proton beam of iThemba LABS on a tandem natural silver target (Ag/Ag) has been developed. The tandem targets (each target with a mass of 9 g and a thickness of 3 mm) were placed in the high energy slot (62.515 MeV - 40.173 MeV) and low energy slot (38.652 MeV – 0 MeV) to produce the bulk 103Pd and 109Cd, respectively. The radiochemical separation of the Pd radionuclides (103Pd, 100Pd) and the co-produced Rh radioisotopes (mainly 101Rh and 100Rh which are produced from decay of their Pd parents) from the bulk natAg was achieved using a Chelex chelating resin column. In the preliminary studies, different size columns (3 cm x 1 cm, 11 cm x 1 cm, 13 cm x 1 cm and 16 cm x 1.5 cm) were investigated to determine the optimal column conditions for the separation. It was determined that the optimal conditions for the chemical separation was with a 13 cm x 1 cm resin column with the elution of Rh and Ag radionuclides carried out with 1 M HNO3 and the elution of Pd radionuclides with 10 M HCl. No Ag or Rh impurities were detected in the final product and the average recovery of Pd was > 96 %. This work was repeated using a ―hot‖ irradiated Ag target and the chemical processing was done in a hot cell using the same resin column conditions. The recovery of the high purity 103Pd from the irradiated natAg target was found to be > 95 %. The radiochemical separation of 109Cd from the bulk natAg target was done in two parts. In the first part, the precipitation method was used to reduce the silver into a metallic form using 30 g of Cu turnings. The resulting 109Cd filtrate was loaded onto a AG-X10 anion exchange resin column (6 cm x 1 cm). For the optimal chemical separation, the elution of Ag and Cu(II) was carried out with 2 M HCl containing H2O2 and the elution of 109Cd was accomplished with 1 M HNO3. The recovery yield of 109Cd was > 99 %. / Chemistry / M.Sc. (Chemistry)
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The production of 103Pd and 109Cd using proton irradiated tandem natAg/natAg targetsIneza, Claire 03 1900 (has links)
103Pd is an important therapeutic radionuclide and has recently found great interest due to its higher radiobiologic effect. 109Cd decays by electron capture and is generally used as calibration sources in industrial and medical fields. A new method for the production of 103Pd and 109Cd using the 66 MeV proton beam of iThemba LABS on a tandem natural silver target (Ag/Ag) has been developed. The tandem targets (each target with a mass of 9 g and a thickness of 3 mm) were placed in the high energy slot (62.515 MeV - 40.173 MeV) and low energy slot (38.652 MeV – 0 MeV) to produce the bulk 103Pd and 109Cd, respectively. The radiochemical separation of the Pd radionuclides (103Pd, 100Pd) and the co-produced Rh radioisotopes (mainly 101Rh and 100Rh which are produced from decay of their Pd parents) from the bulk natAg was achieved using a Chelex chelating resin column. In the preliminary studies, different size columns (3 cm x 1 cm, 11 cm x 1 cm, 13 cm x 1 cm and 16 cm x 1.5 cm) were investigated to determine the optimal column conditions for the separation. It was determined that the optimal conditions for the chemical separation was with a 13 cm x 1 cm resin column with the elution of Rh and Ag radionuclides carried out with 1 M HNO3 and the elution of Pd radionuclides with 10 M HCl. No Ag or Rh impurities were detected in the final product and the average recovery of Pd was > 96 %. This work was repeated using a ―hot‖ irradiated Ag target and the chemical processing was done in a hot cell using the same resin column conditions. The recovery of the high purity 103Pd from the irradiated natAg target was found to be > 95 %. The radiochemical separation of 109Cd from the bulk natAg target was done in two parts. In the first part, the precipitation method was used to reduce the silver into a metallic form using 30 g of Cu turnings. The resulting 109Cd filtrate was loaded onto a AG-X10 anion exchange resin column (6 cm x 1 cm). For the optimal chemical separation, the elution of Ag and Cu(II) was carried out with 2 M HCl containing H2O2 and the elution of 109Cd was accomplished with 1 M HNO3. The recovery yield of 109Cd was > 99 %. / Chemistry / M.Sc. (Chemistry)
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Vývoj techniky difúzního gradientu v tenkém filmu (DGT) pro stanoveni rtuti ve vodných systémech. / Development of Diffusive Gradients in Thin Films Technique for Determination of Mercury in Aquatic SystemsSzkandera, Roman January 2011 (has links)
The theoretical part of this doctoral thesis deals with determination of mercury and its species in aquatic systems. Special attention is paid to the use in situ sampling technique diffusive gradients in thin films technique (DGT) and its development. Current resin gels used for determination of mercury by DGT technique Duolite GT-73, Chelex-100 and Spheron-Thiol are described. Moreover, new types of resin gels including Iontosorb AV modified by imidazole or 6-mercaptopurine and commercially available titanium dioxide. Preparations of resin gels and their basic tests in model solution according to DGT Research are described. Mercury accumulation in relation to time and basic recovery test were tested and capacity of resins was determined. All tested resins meet the requirements of basic DGT Research tests and relative standard deviations of mercury in recovery tests were lower than 10 %. The sorption capacity of resins varied from 1,5 to 6 µmol.l-1 and decreased in following order: Duolite GT-73 > ISAV-IM > Chelex-100 > Spheron-Thiol > TiO2 > ISAV-MP. Mercury sorption on resins was investigated under conditions similar to those in natural waters. It was found that the ionic strength commonly occurring in natural waters does not affect the determination of mercury. The presence of chlorides significantly affects the determination of mercury using DGT with titanium dioxide and therefore this sorbent can not be recommended for the determination of mercury in sea waters. The accumulated amount of mercury, depending on the pH shows that all the sorbents can be used in natural waters with pH in the range form 4 to 8. Mercury sorption is most affected by the presence of humic acids, especially at ion-exchange resins containing other than thiol functional groups. The exception is titanium dioxide for which physical sorption of humic acid metal complexes is typical. Cadmium and copper in model solutions in the molar balance of the excess mostly influenced the sorption of mercury on Chelex-100 and Spheron-Thiol resins. After laboratory tests, the DGT units with studied sorbents were used for the determination of mercury in natural waters of South Moravia (Svratka, Jihlava and Svitava river). Mercury concentration determined using DGT units containing Duolite GT-73 resin was comparable to the total dissolved concentration of mercury in river water provided by direct determination using AAS technique. Order of magnitude smaller concentrations than the total dissolved mercury concentration were found using DGT containing Spheron-Thiol and ISAV-MP resins. These sorbents are probably able to capture only mercury present in the form of labile complexes. This can be used for speciation analysis if more DGT units with different resins are deployed together. Subtracting the measured DGT Spheron-Thiol or ISAV-MP concentrations from the DGT Duolite GT-73 concentration, information about the amount of mercury present in the form of stabile complexes can be obtained. The amount of mercury determined after application of DGT units containing ISAV-IM, Chelex 100 or TiO2 can probably represent the mercury fraction bound in even weaker complexes than fraction determined by Spheron-Thiol and ISAV-MP DGT.
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Studium vlastností sorpčních gelů pro stanovení rtuti technikou DGT. / Characterization of the resin gels for mercury determination by DGT technique.Finsterlová, Hana January 2009 (has links)
The aim of this thesis is testing of resin gels used in diffusive gradients in thin films technique (DGT) for determination of mercury in natural waters. The sorbets, chosen for preparation of resing gels were: Duolit GT- 73, Spheron- Thiol, and Chelex 100 and newly modified sorbent Iontosorb AV. At the beginning of work, the preparation procedure of all resing gels was optimized. After optimalization of preparation procedure the resin gels were tested in mercury model solutions. The recovery test and time dependence test were performed. When the basic tests were finished, they were followed by the tests of influence of natural ligand (humic acids and chlorides), and other parameters (above all pH and ionic strenght), on mercury determination by DGT technique.
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