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1.
Methyl mercury was determined by gas chromatography, microwave induced plasma, atomic emission spectrometry (GC-MIP-AES) using two different methods. One was based on extraction of mercury species into toluene, pre-concentration by evaporation and butylation of methyl mercury with a Grignard reagent followed by determination. With the other, methyl mercury was extracted into dichloromethane and back extracted into water followed by in situ ethylation, collection of ethylated mercury species on Tenax and determination. The accuracy of the entire procedure based on butylation was validated for the individual steps involved in the method. Methyl mercury added to various types of soil samples showed an overall average recovery of 87.5%. Reduced recovery was only caused by losses of methyl mercury during extraction into toluene and during pre-concentration by evaporation. The extraction of methyl mercury added to the soil was therefore quantitative. Since it is not possible to directly determine the extraction efficiency of incipient methyl mercury, the extraction efficiency of total mercury with an acidified solution containing CuSO4 and KBr was compared with high-pressure microwave acid digestion. The solvent extraction efficiency was 93%. For the IAEA 356 sediment certified reference material, mercury was less efficiently extracted and determined methyl mercury concentrations were below the certified value. Incomplete extraction could be explained by the presence of a large part of inorganic sulfides, as determined by x-ray absorption near-edge structure spectroscopy (XANES). Analyses of sediment reference material CRM 580 gave results in agreement with the certified value. The butylation method gave a detection limit for methyl mercury of 0.1 ng g(-1), calculated as three times the standard deviation for repeated analysis of soil samples. Lower values were obtained with the ethylation method. The precision, expressed as RSD for concentrations 20 times above the detection limit, was typically 5%.  相似文献   

2.
Methyl mercury was determined by gas chromatography, microwave induced plasma, atomic emission spectrometry (GC-MIP-AES) using two different methods. One was based on extraction of mercury species into toluene, pre-concentration by evaporation and butylation of methyl mercury with a Grignard reagent followed by determination. With the other, methyl mercury was extracted into dichloromethane and back extracted into water followed by in situ ethylation, collection of ethylated mercury species on Tenax and determination. The accuracy of the entire procedure based on butylation was validated for the individual steps involved in the method. Methyl mercury added to various types of soil samples showed an overall average recovery of 87.5%. Reduced recovery was only caused by losses of methyl mercury during extraction into toluene and during pre-concentration by evaporation. The extraction of methyl mercury added to the soil was therefore quantitative. Since it is not possible to directly determine the extraction efficiency of incipient methyl mercury, the extraction efficiency of total mercury with an acidified solution containing CuSO4 and KBr was compared with high-pressure microwave acid digestion. The solvent extraction efficiency was 93%. For the IAEA 356 sediment certified reference material, mercury was less efficiently extracted and determined methyl mercury concentrations were below the certified value. Incomplete extraction could be explained by the presence of a large part of inorganic sulfides, as determined by ¶x-ray absorption near-edge structure spectroscopy (XANES). Analyses of sediment reference material CRM 580 gave results in agreement with the certified value. The butylation method gave a detection limit for methyl mercury of 0.1 ng g–1, calculated as three times the standard deviation for repeated analysis of soil samples. Lower values were obtained with the ethylation method. The precision, expressed as RSD for concentrations 20 times above the detection limit, was typically 5%.  相似文献   

3.
Species-specific stable isotope dilution in combination with gold trap- or gas chromatography (GC)-inductively coupled plasma mass spectrometry (ICP-MS) is reported for the determination of inorganic mercury and methylmercury in diatoms (Chaetoceros curvisetus). The optimum conditions for the separation parameters were established. The isotope dilution analysis was performed using 199Hg-enriched Hg2+ and laboratory-synthesized 201Hg-enriched methylmercury. The absolute detection limits obtained with isotope dilution-ICP-MS were 9 pg for total mercury and 0.6 pg for methylmercury. The relative error of 7 Hg isotopic abundances based on the peak area measurements was better than 2.0% for 20 pg of methylmercury (as Hg) and 250 pg of inorganic mercury. The accuracy of the method was validated with a biological certified reference material. The developed method was then applied to investigate the uptake of inorganic mercury and methylmercury by C. curvisetus. Continuous uptake of inorganic mercury and methylmercury was observed during 5 days of incubation.  相似文献   

4.
Several hyphenated analytical techniques, including gas chromatography (GC) coupled with atomic fluorescence spectrometry (AFS), microwave-induced plasma atomic emission spectrometry (AES), and mass spectrometry (MS), have been evaluated for methylmercury and ethylmercury analysis following aqueous derivatization with both sodium tetraethylborate and sodium tetraphenylborate. Both GC-AFS and GC-AES were shown to be excellent techniques with detection limits in the range of sub-picogram levels (0.02-0.04 pg as Hg). Both techniques have wide linear ranges, although setting of the AFS sensitivity has to be selected manually based on the concentration of mercury in the sample. Phenylation seems to be more favorable in this study because of its capability of distinguishing between ethylmercury and inorganic mercury, and low cost compared to ethylation. Although sensitivity of GC-MS is poor with detection limits ranging from 30 to 50 pg as Hg, it is an essential technique for confirmation of the derivatization products.  相似文献   

5.
A multi-element, element-specific detector for gas chromatography (GC) based on atomic emission spectroscopy (AES) with a microwave induced plasma (MIP) source was tested on some environmental samples. As derivatization procedure, direct aqueous phase ethylation and chelation/extraction followed by Grignard reaction were tested on the following ions: methylmercury, ethylmercury, phenylmercury, mercury(II), trimethyllead, dimethyllead, lead(II), trimethyltin, dimethyltin, triethyltin, tripropyltin, tributyltin, dibutyltin, butyltin, and tin(IV). For mercury species a direct aqueous phase phenylation was successfully tested. The different methods of derivatization are compared, and the performance (sensitivity, linearity) of the GC-MIP-AES system is discussed. Some examples of application to environmental samples (biological tissues) are given.  相似文献   

6.
Liang L  Horvat M  Bloom NS 《Talanta》1994,41(3):371-379
An improvement has been made in previous mercury speciation methods, which omits the use of liquid nitrogen by modifying the GC conditions. In addition, the sometimes observed thermal decomposition of ethylation derivatives in the process of desorbing the compounds to the GC column has been investigated and overcome. The resulting improvements have allowed simultaneous determination of methylmercury (MMHg) and inorganic mercury (Hg(II)). They have also increased the precision of the ethylation reaction and refined the MMHg determination. Optimal conditions for MMHg were confirmed and supplemented, while the parameters for dimethyl mercury (DMHg) and Hg(II) were thoroughly investigated for the first time. The absolute detection limits (DL) for 2sigma of the reagent blanks as Hg and about 0.6, 0.6 and 1.3 pg for DMHg, MMHg and Hg(II), respectively. The improved method is five-fold faster than the original method, allowing up to 80 samples to be analyzed within 8 hr.  相似文献   

7.
An analytical procedure for the determination of methylmercury in human hair after acid digestion using aqueous ethylation, headspace solid-phase microextraction sampling and final gas chromatography-cold-vapour atomic fluorescence spectrometry detection is described. Acid digestion, extraction procedure and chromatographic conditions were optimised. An optimal linear range using standard mercury solutions was found and concentration detection limits for the mercury species, MeHg and Hg2+, were about 50 and 80 ng/g, respectively, for 100 mg of human hair. The reproducibility of the developed analytical procedure assessed for hair samples with incurred MeHg was better than 18% (n=5). A certified reference material from the National Institute of Environmental Studies (Japan) was used for validation. Analysis of human hair collected from urban inhabitants was performed and the mean value of methylmercury content in hair samples was 0.764 +/- 0.732 microg/g for the population tested. The developed analytical method is simple, fast and a suitable procedure for the monitoring and screening of human exposure to methylmercury.  相似文献   

8.
Two speciated isotope dilution (SID) approaches consisting of a single-spike (SS) method and a double-spike (DS) method including a reaction/transformation model for the correction of inadvertent transformations affecting mercury species were compared in terms of accuracy, method performance, and robustness for the simultaneous determination of methylmercury (MeHg), inorganic mercury (iHg), and total mercury (HgT) concentrations in five biological Standard Reference Materials (SRMs). The SRMs consisted of oyster and mussel tissue materials displaying different mercury species concentration levels and different textural/matrix properties including freeze-dried (FD) materials (SRMs 1566b, 2976, and 2977) and cryogenically prepared and stored fresh-frozen (FF) materials (SRMs 1974a, 1974b). Each sample was spiked with (201)iHg (Oak Ridge National Laboratory, ORNL) and Me(202)Hg (Institute for Reference Materials and Measurements. IRMM-670) solutions and analyzed using alkaline microwave digestion, ethylation, and gas chromatography inductively coupled plasma mass spectrometry (GC/ICP-MS). The results obtained by the SS-SID method suggested that FF and FD materials are not always commutable for the simultaneous determination of iHg, MeHg, and HgT, due to potential transformation reactions resulting probably from the methodology and/or from the textural/matrix properties of the materials. These transformations can occasionally significantly affect mercury species concentration results obtained by SS-SID, depending on the species investigated and the materials considered. The results obtained by the DS-SID method indicated that the two classes of materials were commutable. The simultaneous and corrected concentrations of iHg, MeHg, and HgT obtained by this technique were not found to be statistically different form the certified and reference concentration together with their expanded uncertainty budgets for the five SRMs investigated, exemplifying the robustness, the accuracy, and the improved commutability of this method compared to SS-SID measurements.  相似文献   

9.
Hollow-cathode (HC) radiofrequency glow-discharge (rf-GD) optical-emission spectrometry (OES) has been used as detector for the determination of inorganic mercury by cold-vapour (CV) generation in a flow-injection (FI) system. Both NaBH4 and SnCl2 were evaluated as reducing reagents for production of mercury CV. The conditions governing the discharge (pressure, He flow rate, and delivered power) and Hg CV generation (NaBH4 or SnCl2 concentration and reagent flow rate) were optimized using both reducing agents. The analytical performance characteristics of FI-CV-rf-GD-OES for mercury detection were evaluated at the 253.6 nm emission mercury line. Detection limits (DL) of 0.2 ng mL(-1) using SnCl2 and 1.8 ng mL(-1) using NaBH4 were obtained (100 microliter sample injections were used). When the optimized experimental conditions using SnCl2 had been determined, the analytical potential of this CV-rf-GD-OES method was investigated as on-line detector for high-performance liquid chromatographic (HPLC) speciation of mercury (Hg(II) and methylmercury). The HPLC-CV-rf-GD-OES detection limits for 100 microliter sample injections were found to be 1.2 and 1.8 ng mL(-1) (as mercury) of inorganic mercury and methylmercury, respectively. The reproducibility observed was below +/- 8% for both species. Finally, the HPLC-CV-rf-GD-OES system developed was successfully applied to the determination of methylmercury (speciation) in two certified reference materials, Dorm-2 and Dolt-2.  相似文献   

10.
An on-line inorganic and organomercury species separation, preconcentration and determination system consisting of cold vapor atomic absorption spectrometry (CV-AAS or CV-ETAAS) coupled to a flow injection (FI) method was studied. The inorganic mercury species was retained on a column (i.d., 3 mm; length 3 cm) packed to a height of 0.7 cm with a chelating resin aminopropyl-controlled pore glass (550 A) functionalized with [1,5-bis (2 pyridyl)-3-sulphophenyl methylene thiocarbonohydrazyde] placed in the injection valve of a simple flow manifold. Methylmercury is not directly determined. Previous oxidation of the organomercurial species permitted the determination of total mercury. The separation of mercury species was obtained by the selective retention of inorganic mercury on the chelating resin. The difference between total and inorganic mercury determined the organomercury content in the sample. The inorganic mercury was removed on-line from the microcolumn with 6% (m/v) thiourea. The mercury cold vapor generation was performed on-line with 0.2% (m/v) sodium tethrahydroborate and 0.05% (m/v) sodium hydroxide as reducing solution. The determination was performed using CV-AAS and CV-ETAAS, both approaches have been used and compared for the speciation of mercury in sea food. A detection limit of 10 and 6 ng l(-1) was achieved for CV-AAS and CV-ETAAS, respectively. The precision for 10 replicate determinations at the 1 microg l(-1) Hg level was 3.5% relative standard deviation (R.S.D.), calculated from the peak heights obtained. Both approaches were validated with the use of two certified reference materials and by spiking experiments. By analyzing the two biological certified materials, it was evident that the difference between the total mercury and inorganic mercury corresponds to methylmercury. The concentrations obtained by both techniques were in agreement with the certified values or with differences of the certified values for total Hg(2+) and CH(3)Hg(+), according to the t-test for a 95% confidence level. It is amazing how this very simple method is able to provide very important information on mercury speciation.  相似文献   

11.
《Microchemical Journal》2010,94(2):206-210
A simple and reliable method to determine total and inorganic mercury in biological certified reference material (CRM) by cold vapor atomic absorption spectrometry (CV AAS) is proposed. After the CRM treatment at room temperature with tetramethylammonium hydroxide (TMAH), inorganic mercury is determined by CV AAS. Total mercury is measured by the same technique, after sample acid digestion in a microwave oven. Organic mercury, basically methylmercury, is obtained by difference. In both procedures, the quartz tube is kept at room temperature. By means of analysis of the following reference materials: pig kidney, lobster hepatopancreas, dogfish liver and mussel tissue, it was clear that the difference between the total and inorganic mercury concentrations agrees with the methylmercury concentration. Only one calibration curve against aqueous standards in acidic medium was carried out for both procedures. The concentrations obtained by both procedures are in agreement with the certified values according to the t-test at a 95% confidence level. The relative standard deviations were lower than 3.0% for digested CRM and 6.0% for CRM treated with TMAH for most of the samples. The limits of detection in the samples were 0.02 µg g 1 and 0.04 µg g 1 for inorganic and total Hg, respectively, since the sample mass for total mercury was half of that for inorganic mercury determination. Simplicity and high efficiency without using chromatographic techniques are some of the qualities of the proposed method, being adequate for fractionation analysis of mercury in biological samples.  相似文献   

12.
The analysis of methylmercury in extracts from environmental solid samples by gas chromatography coupled to microwave induced plasma atomic emission spectrometry (GC-MIP/AES) after the ethylation of the extract and the preconcentration of the volatile products in hexane has been critically investigated. In order to correct potential sources of random error along the analytical procedure affecting the overall repeatability of the analysis, the use of the inorganic mercury naturally occurring in the sample as internal standard in the analysis of methylmercury is proposed. A study to establish the best conditions to achieve a quantitative recovery of methylmercury without damaging its chemical structure has also been carried out. Magnetic stirring (without heating) of the sediment or fish tissue with 2 mol dm−3 HNO3 or 10% methanolic KOH, respectively, during 90 min has been considered as the most effective procedure to release methylmercury preserving its structure. The proposed method has been validated using certified reference materials (CRM-580, CRM-463 and DOLT-2), assessing its quality in terms of accuracy, repeatability and detection limit. Finally, several sediment and fish samples collected in the estuary of the Nerbioi-Ibaizabal (Bilbao, Basque Country) have been analyzed following the procedures proposed. The results obtained show the validity of the proposed method to analyze real samples.  相似文献   

13.
A simple and reliable method to determine total and inorganic mercury in biological certified reference material (CRM) by cold vapor atomic absorption spectrometry (CV AAS) is proposed. After the CRM treatment at room temperature with tetramethylammonium hydroxide (TMAH), inorganic mercury is determined by CV AAS. Total mercury is measured by the same technique, after sample acid digestion in a microwave oven. Organic mercury, basically methylmercury, is obtained by difference. In both procedures, the quartz tube is kept at room temperature. By means of analysis of the following reference materials: pig kidney, lobster hepatopancreas, dogfish liver and mussel tissue, it was clear that the difference between the total and inorganic mercury concentrations agrees with the methylmercury concentration. Only one calibration curve against aqueous standards in acidic medium was carried out for both procedures. The concentrations obtained by both procedures are in agreement with the certified values according to the t-test at a 95% confidence level. The relative standard deviations were lower than 3.0% for digested CRM and 6.0% for CRM treated with TMAH for most of the samples. The limits of detection in the samples were 0.02 µg g− 1 and 0.04 µg g− 1 for inorganic and total Hg, respectively, since the sample mass for total mercury was half of that for inorganic mercury determination. Simplicity and high efficiency without using chromatographic techniques are some of the qualities of the proposed method, being adequate for fractionation analysis of mercury in biological samples.  相似文献   

14.
A comparative study of three mercury chelate forming reagents [diethyldithiocarbamate, pyrrolidin-1-yldithioformate and diphenylthiocarbazone (dithizone)] has been carried out for the preconcentration of ultratrace amounts of inorganic mercury and methylmercury in silica C(18) minicolumns as the solid sorbent. Sample flow injection in-line sorbent extraction was coupled with continuous cold vapour atomic absorption spectrometry (CVAAS) for detection. Results showed the superiority of the carbamate type reagents over the dithizone for the on-line formation and preconcentration of the corresponding mercury chelates. Using diethyldithiocarbamate (DDC) as reagent, aqueous sample volumes of 100 ml can be preconcentrated with 100% efficiency for both inorganic mercury and methylmercury. Quantitative release of the retained DDC chelates was obtained for volumes of eluent (ethanol) of 50 microl. Following the proposed procedure, detection limits of 16 ng/l. of mercury were achieved for sample volumes of 25 ml. The relative standard deviation was +/- 3.4% at 0.5 microg/l. Hg(II) levels. The method has been successfully applied to the determination of low levels of mercury in sea-water.  相似文献   

15.
Summary An analytical procedure is described for the determination of methylmercury and ethylmercury compounds in fish and sediment samples, using gas chromatography atomic fluorescence spectrometry following aqueous phenylation with sodium tetraphenylborate. The derivatization products were identified by gas chromatography mass spectrometry. The advantages of using phenylation with sodium tetraphenylborate over ethylation with sodium tetraethylborate are discussed. The validation of the analytical procedure was performed by analyzing standard reference material (DORM-2). Applications for the analysis of fish and sediment samples were carried out and compared to other techniques.  相似文献   

16.
Peng ZL  Qu F  Song G  Lin JM 《Electrophoresis》2005,26(17):3333-3340
A simple and rapid nonaqueous capillary electrophoresis method for simultaneous separation of four kinds of mercury species, namely inorganic mercury, methylmercury, ethylmercury, and phenylmercury, is reported. The effective mobilities of organomercury in aqueous and nonaqueous electrolytes were compared. Imidazole was confirmed not only as a co-ion for the separation but also as an online complexing reagent for mercury species. The optimum conditions for separation were achieved by using methanol solvent containing 0.15 M acetic acid and 15 mM imidazole as electrolyte. The sensitive detection of mercury species was accomplished at 191 nm.  相似文献   

17.
Two methods, based on hollow fiber liquid–liquid–liquid (three phase) microextraction (HF-LLLME) and hollow fiber liquid phase (two phase) microextraction (HF-LPME), have been developed and critically compared for the determination of methylmercury content in human hair and sludge by graphite furnace atomic absorption spectrometry (GFAAS). In HF-LPME, methylmercury was extracted into the organic phase (toluene) prior to its determination by GFAAS, while inorganic mercury remained as a free species in the sample solution. In HF-LLLME, methylmercury was first extracted into the organic phase (toluene) and then into the acceptor phase (4% thiourea in 1 mol L 1 HCl) prior to its determination by GFAAS, while inorganic mercury remained in the sample solution. The total mercury was determined by inductively coupled plasma-mass spectrometry (ICP-MS), and the levels of inorganic mercury in both HF-LLLME and HF-LPME were obtained by subtracting methylmercury from total mercury. The factors affecting the microextraction of methylmercury, including organic solvent, extraction time, stirring rate and ionic strength, were investigated and the optimal extraction conditions were established for both HF-LLLPME and HF-LPME. With a consumption of 3.0 mL of the sample solution, the enrichment factors were 204 and 55 for HF-LLLPME and HF-LPME, respectively. The limits of detection (LODs) for methylmercury were 0.1 μg L 1 and 0.4 μg L 1 (as Hg) with precisions (RSDs (%), c = 5 μg L− 1 (as Hg), n = 5) of 13% and 11% for HF-LLLPME–GFAAS and HF-LPME–GFAAS, respectively. For ICP-MS determination of total mercury, a limit of detection of 39 ng L 1 was obtained. Finally, HF-LLLME–GFAAS was applied to the determination of methylmercury content in human hair and sludge, and the recoveries for the spiked samples were in the range of 99–113%. In order to validate the method, HF-LLLME–GFAAS was also applied to the analysis of a certified reference material of NRCC DORM-2 dogfish muscle, and the determined values were in good agreement with the certified values.  相似文献   

18.
Sample preparation methods for non-separation cold vapor atomic absorption spectrometry (CVAAS) sequential inorganic mercury speciation in biological certified reference materials (CRMs) were investigated. The methylmercury concentration was calculated as the difference between total and inorganic mercury. Microwave-assisted decomposition method, and three ultrasonic extraction procedures based on acid leaching with HCl and HCOOH and solubilization with TMAH were employed as sample preparation methods. The replacement of a sample decomposition procedure by extraction prior to analysis by CVAAS, as well as the aspect of speciation analysis is discussed. The limits of detection in the sample were determined as 50 and 10 ng L−1 for inorganic and total mercury, which corresponds to absolute detection limits of 40 and 8 ng g−1 for inorganic and total mercury, respectively. The results were in good agreement with the 95% confidence level t-test of the certified values for total and inorganic mercury in the reference materials investigated. From the analysis of the CRMs, it was evident that the difference between the total and inorganic mercury concentrations agrees with the methylmercury concentration. The relative standard deviation was better than 11% for most of the samples.   相似文献   

19.
黄会秋  黄莉来  夏坪 《色谱》2016,34(9):918-924
建立了同时测定水产品中甲基汞和无机砷的水相衍生-气相色谱-质谱联用分析方法。采用6 mol/L盐酸超声辅助提取水产品中的甲基汞与无机砷,于-10℃冷冻离心后,提取液中的无机砷(As3+与As5+)与2,3-二巯基丙醇(BAL)溶液于35℃水浴中衍生反应30 min,用甲苯萃取衍生物与甲基汞,萃取前加入无水乙醇避免非脂成分进入有机相中,向甲苯萃取液中添加甲基汞的衍生剂四苯硼钠溶液(pH 3.6)。采用选择离子监测(SIM)模式,外标法测定水产品中的甲基汞与无机砷。结果表明,水产品中甲基汞与无机砷在5~2000 μg/L范围内线性关系良好,相关系数(r)均大于0.999;检出限为0.7~3 μg/kg (S/N=3)。在10、100、1000 μg/kg加标水平下,方法加标回收率为80.0%~110.0%,相对标准偏差(n=6)为2.5%~9.4%。该方法操作简便、准确、灵敏度高,已成功应用于水产品中无机砷与甲基汞的食品污染物风险监测中。  相似文献   

20.
This paper reports the development of an analytical approach for speciation analysis of mercury at ultra-trace levels on the basis of solid-phase microextraction and multicapillary gas chromatography hyphenated to inductively coupled plasma-time-of-flight mass spectrometry. Headspace solid-phase microextraction with a carboxen/polydimethylsyloxane fiber is used for extraction/preconcentration of mercury species after derivatization with sodium tetraethylborate and subsequent volatilization. Isothermal separation of methylmercury (MeHg), inorganic mercury (Hg2+) and propylmercury (PrHg) used as internal standard is achieved within a chromatographic run below 45 s without the introduction of spectral skew. Method detection limits (3 x standard deviation criteria) calculated for 10 successive injections of the analytical reagent blank are 0.027 pg g(-1) (as metal) for MeHg and 0.27 pg g(-1) for Hg2+. The repeatability (R.S.D., %) is 3.3% for MeHg and 3.8% for Hg2+ for 10 successive injections of a standard mixture of 10pg. The method accuracy for MeHg and total mercury is validated through the analysis of marine and estuarine sediment reference materials. A comparison of the sediment data with those obtained by a purge-and-trap injection (PTI) method is also addressed. The analytical procedure is illustrated with some results for the ultra-trace level analysis of ice from Antarctica for which the accuracy is assessed by spike recovery experiments.  相似文献   

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