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1.
An important but commercially unavailable compound isotopically enriched monoethylmercury chloride (C2H5201HgCl), has been synthesized from commercially available 201HgO (98.11% enriched isotopic purity) and tetraethyltin. The required synthesis time is 1 h at 90 °C, and the product is the single product of monoethylmercury chloride, yielding more than 95% as 201Hg in C2H5201Hg+ (98.19 ± 0.22% enriched isotopic purity). The synthesized product was analyzed with high‐performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC‐ICP‐MS) to determine its concentration, isotopic composition and purity. The synthetic isotopically enriched monoethylmercury synthesized can be used in speciated isotope dilution mass spectrometry (SIDMS) and isotope dilution mass spectrometry (IDMS) analyses as a standard. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
2.
A simple and efficient extraction method based on acidic leaching has been developed for measurement of methylmercury (MeHg) in benthic organisms and plant material. Methylmercury was measured by speciated isotope-dilution mass spectrometry (SIDMS), using gas chromatography interfaced with inductively coupled plasma mass spectrometry (GC–ICP–MS). Reagent concentration and digestion temperature were optimized for several alkaline and acidic extractants. Recovery was evaluated by addition of MeHg enriched with CH3201Hg+. Certified reference materials (CRM) were used to evaluate the efficiency of the procedure. The final digestion method used 5 mL of 4 mol L–1 HNO3 at 55°C to leach MeHg from tissue and plant material. The digest was further processed by aqueous phase ethylation, without interference with the ethylation step, resulting in 96±7% recovery of CH3201Hg+ from oyster tissue and 93±7% from pine needles. Methylmercury was stable in this solution for at least 1 week and measured concentrations of MeHg in CRM were statistically not different from certified values. The method was applied to real samples of benthic invertebrates and inter-laboratory comparisons were conducted using lyophilized zooplankton, chironomidae, and notonectidae samples.Contribution No. 15 of the Mercury Experiment to Assess Atmospheric Loadings in Canada and the US (METAALICUS). 相似文献
3.
R. C. Rodríguez Martín‐Doimeadios T. Stoichev E. Krupp D. Amouroux M. Holeman O. F. X. Donard 《应用有机金属化学》2002,16(10):610-615
A synthesis method for the micro‐scale laboratory preparation of isotopically enriched monomethylmercury (MMHg) has been successfully established. This compound is an important standard for species‐specific isotope dilution analysis. The isotopically enriched MMHg has been synthesized from commercially available mercury oxide (201HgO) using methylcobalamin co‐enzyme as methylating agent. The time required is less than 2 h and the final yield is about 90%. The proposed method is faster than those previously reported in the literature. It allows work on a micro scale to control the use of expensive enriched isotope standard. It also allows control of unintentional formation of dimethylmercury. The enriched mercury‐containing reaction products were analyzed by capillary gas chromatography coupled to an inductively coupled plasma mass spectrometer after derivatization with sodium tetraethylborate. The isotopic composition, concentration, purity and stability of the synthesized, enriched MMHg have been investigated in order to establish standard protocols for MMHg isotope dilution analysis or isotope labeling incubation experiments. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
4.
Rebecca Wagner Stephanie J. Wetzel John Kern H. M. Skip Kingston 《Journal of mass spectrometry : JMS》2012,47(2):147-154
The employment of chemical weapons by rogue states and/or terrorist organizations is an ongoing concern in the United States. The quantitative analysis of nerve agents must be rapid and reliable for use in the private and public sectors. Current methods describe a tedious and time‐consuming derivatization for gas chromatography–mass spectrometry and liquid chromatography in tandem with mass spectrometry. Two solid‐phase extraction (SPE) techniques for the analysis of glyphosate and methylphosphonic acid are described with the utilization of isotopically enriched analytes for quantitation via atmospheric pressure chemical ionization–quadrupole time‐of‐flight mass spectrometry (APCI‐Q‐TOF‐MS) that does not require derivatization. Solid‐phase extraction‐isotope dilution mass spectrometry (SPE‐IDMS) involves pre‐equilibration of a naturally occurring sample with an isotopically enriched standard. The second extraction method, i‐Spike, involves loading an isotopically enriched standard onto the SPE column before the naturally occurring sample. The sample and the spike are then co‐eluted from the column enabling precise and accurate quantitation via IDMS. The SPE methods in conjunction with IDMS eliminate concerns of incomplete elution, matrix and sorbent effects, and MS drift. For accurate quantitation with IDMS, the isotopic contribution of all atoms in the target molecule must be statistically taken into account. This paper describes two newly developed sample preparation techniques for the analysis of nerve agent surrogates in drinking water as well as statistical probability analysis for proper molecular IDMS. The methods described in this paper demonstrate accurate molecular IDMS using APCI‐Q‐TOF‐MS with limits of quantitation as low as 0.400 mg/kg for glyphosate and 0.031 mg/kg for methylphosphonic acid. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
5.
A field-adapted procedure based on species-specific isotope dilution (SSID) methodology for trace-level determinations of methyl mercury (CH3Hg+) in mire, fresh and sea water samples was developed, validated and applied in a field study. In the field study, mire water samples were filtered, standardised volumetrically with isotopically enriched CH3200Hg+, and frozen on dry ice. The samples were derivatised in the laboratory without further pre-treatment using sodium tetraethyl borate (NaB(C2H5)4) and the ethylated methyl mercury was purge-trapped on Tenax columns. The analyte was thermo-desorbed onto a GC-ICP-MS system for analysis. Investigations preceding field application of the method showed that when using SSID, for all tested matrices, identical results were obtained between samples that were freeze-preserved or analysed unpreserved. For DOC-rich samples (mire water) additional experiments showed no difference in CH3Hg+ concentration between samples that were derivatised without pre-treatment or after liquid extraction. Extractions of samples for matrix–analyte separation prior to derivatisation are therefore not necessary. No formation of CH3Hg+ was observed during sample storage and treatment when spiking samples with 198Hg2+. Total uncertainty budgets for the field application of the method showed that for analyte concentrations higher than 1.5 pg g–1 (as Hg) the relative expanded uncertainty (REU) was approximately 5% and dominated by the uncertainty in the isotope standard concentration. Below 0.5 pg g–1 (as Hg), the REU was >10% and dominated by variations in the field blank. The uncertainty of the method is sufficiently low to accurately determine CH3Hg+ concentrations at trace levels. The detection limit was determined to be 4 fg g–1 (as Hg) based on replicate analyses of laboratory blanks. The described procedure is reliable, considerably faster and simplified compared to non-SSID methods and thereby very suitable for routine applications of CH3Hg+ speciation analysis in a wide range of water samples. 相似文献
6.
L. Hinojosa Reyes 《Analytica chimica acta》2009,631(2):121-476
A rapid and efficient closed vessel microwave-assisted extraction (MAE) method based on acidic leaching was developed and optimized for the extraction of total mercury (Hg), inorganic mercury (Hg2+) and methylmercury (CH3Hg+) from fish tissues. The quantitative extraction of total Hg and mercury species from biological samples was achieved by using 5 mol L−1 HCl and 0.25 mol L−1 NaCl during 10 min at 60 °C. Total Hg content was determined using inductively coupled plasma mass spectrometry (ICP-MS). Mercury species were measured by liquid chromatography hyphenated with inductively coupled plasma mass spectrometry (LC-ICP-MS). The method was validated using biological certified reference materials ERM-CE464, DOLT-3, and NIST SRM-1946. The analytical results were in good agreement with the certified reference values of total Hg and CH3Hg+ at a 95% confidence level. Further, accuracy validation using speciated isotope-dilution mass spectrometry (SIDMS, as described in the EPA Method 6800) was carried out. SIDMS was also applied to study and correct for unwanted species transformation reactions during and/or after sample preparation steps. For the studied reference materials, no statistically significant transformation between mercury species was observed during the extraction and determination procedures. The proposed method was successfully applied to fish tissues with good agreement between SIDMS results and external calibration (EC) results. Interspecies transformations in fish tissues were slightly higher than certified reference materials due to differences in matrix composition. Depending on the type of fish tissue, up to 10.24% of Hg2+ was methylated and up to 1.75% of CH3Hg+ was demethylated to Hg2+. 相似文献
7.
Speciation of Mercury in Microalgae by Isotope Dilution-inductively Coupled Plasma Mass Spectrometry
Beibei Song Huijun He Lufeng Chen Shifeng Yang Yin Yongguang 《Analytical letters》2017,50(13):2161-2176
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
8.
Reyes LH Mizanur Rahman GM Fahrenholz T Skip Kingston HM 《Analytical and bioanalytical chemistry》2008,390(8):2123-2132
Eight different analytical extraction procedures commonly used to extract mercury species from biological samples were evaluated
by analyzing Tuna Fish Tissue Certified Reference Material (ERM-CE464) certified for the content of total mercury and methylmercury.
Speciated isotope dilution mass spectrometry (SIDMS; US Environmental Protection Agency’s method 6800) was utilized to evaluate
and effectively compensate for potential errors during measurement and accurately quantify mercury species using all the extraction
methods. SIDMS was used to accurately evaluate species transformations during sample pretreatment, preparation and analysis
protocols. The extraction methods tested in this paper were based on alkaline extraction with KOH or tetramethylammonium hydroxide;
acid leaching with HCl, HNO3 or CH3COOH; extraction with l-cysteine hydrochloride; and enzymatic digestion with protease XIV. Detection of total mercury and mercury species from all
extraction methods was carried out by inductively coupled plasma mass spectrometry (ICP-MS) and high-performance liquid chromatography–ICP-MS,
respectively. Microwave-assisted extraction and ultrasound-assisted extraction were found to be the most efficient alkaline
digestion protocols that caused the lowest levels of transformation of mercury species (6% or less). Extraction with 5 M HCl
or enzymatic digestion with protease resulted in the second-highest extraction efficiency, with relatively lower transformation
of methylmercury to inorganic mercury (3 and 1.4%, respectively). Despite frequent use of acid leaching for the extraction
of mercury species from tuna fish samples, the lowest extraction efficiencies and the highest mercury species transformation
were obtained when microwave-assisted extraction with 4 M HNO3 or CH3COOH was used. Transformations as high as 30% were found using some literature protocols; however, all the extractions tested
produced accurate quantitation when corrected in accordance with the SIDMS method standardized in the US Environmental Protection
Agency’s method 6800.
Figure Determinative CRM Tuna Fish Tissue Methylmercury Calibration vs. Determinative Calculation. 相似文献
9.
Species-specific (SS) isotope dilution analysis with gel electrophoresis (GE)-laser ablation (LA)-ICP-MS is a promising technique for the quantification of particular metal-binding proteins in biological samples. However, unavailable isotopically enriched spike and metal losses in GE separation are main limitations for SS-isotope dilution PAGE-LA-ICP-MS. In this study, we report for the first time the absolute quantification of transferrin (Tf) and albumin (Alb) in human serum by non-denaturing (native) GE combined with species-unspecific isotope dilution mass spectrometry (IDMS). In order to achieve a homogeneous distribution of both protein and isotope-enriched spike (simulated isotope equilibration), immersing the protein strips with 34S spike solution after gel electrophoresis was demonstrated to be an effective way of spike addition. Furthermore, effects of immersion time and 34S spike concentration were investigated to obtain optimal conditions of the post-electrophoresis isotope dilution method. The relative mass of spike and ablated sample (msp/msam) in IDMS equation was calculated by standard Tf and Alb proteins, which could be applied to the quantification of Tf and Alb in ERM-DA470k/IFCC for method confirmation. The results were in agreement with the certified value with good precision and small uncertainty (1.5–3%). In this method, species-specific spike protein is not necessary and the integrity of the heteroatom-protein could be maintained in sample preparation process. Moreover, the application of species-unspecific isotope dilution GE-LA-ICP-MS has the potential to offer reliable, direct and simultaneous quantification of proteins after conventional 1D and 2D gel electrophoretic separations. 相似文献
10.
Chaonan Xie Qin Li Gang Han Huan Liu Jien Yang Jincheng Li 《Biomedical chromatography : BMC》2019,33(5)
Tricaine methanesulfonate is one of most commonly used anesthetics in fish during blood sampling, artificial propagation and long‐distance transportation. In this study, an accurate method for the quantitative determination of tricaine in fish samples by a stable isotope dilution assay coupled with high‐performance liquid chromatography–triple quadrupole mass spectrometry was developed. Tricaine‐D5 was synthesized and used as an isotopically labeled internal standard for the determination of tricaine. The analytical performance of the method was validated for tricaine determination in marine fish and freshwater fish. The determination of tricaine was linear in the range of 2.0–200.0 μg L?1. The limit of detection and limit of quantitation for fish muscle tissues were 1.0 and 4.0 μg kg?1, respectively. Good recoveries were obtained in the range of 92.08–97.50%. The inter‐ and intra‐assay relative standard deviations (RSD values) were investigated, and the values were 0.39–3.01 and 0.85–2.77%, respectively. The values of CCα and CCβ were 10.21–10.43 and 10.42–10.87 μg kg?1, respectively. The clearance of MS‐222 from grass carp was further studied using our method. The results demonstrate that MS‐222 could be well absorbed and rapidly eliminated after bath administration. 相似文献
11.
The organosilicone surfactant Silwet L‐77® (L‐77), used as an agrochemical adjuvant, is a mixture comprised predominantly of [(CH3)3SiO]2? (CH3)Si? (CH2)3? (OCH2CH2)n? OCH3 oligomers (n = 3–16, average n ≈ 7.5). The commercially available L‐77 mixture was purified by reversed‐phase high‐performance liquid chromatography (HPLC) to obtain individual trisiloxane surfactant components. Pure oligomers (n = 3, 6 and 9) were also synthesized. Synthesis was achieved by hydrosilylation of monomeric ethoxylate monomethyl ether starting reagents. Pure hexa‐ and nona‐ethylene glycols were produced by condensation of smaller oligomers. Atmospheric‐pressure ionization mass spectrometry (MS) methods were used to characterize fully the commercial L‐77 product and synthesized or isolated components. The application of Fourier‐transform ion cyclotron resonance MS and online HPLC–electrospray ionization MS techniques to the analysis of this surfactant are described here. The application of these analytical techniques also enabled elucidation of the synthetic by‐products present in the commercial formulation. In addition, physico‐chemical properties specific to agrochemical uses, such as droplet spread areas on plant foliage and surface tension for the different oligomer solutions, are also reported. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
12.
Dual-mode heart-cutting two-dimensional liquid chromatography (DMHC 2D-LC) was applied to isotope dilution mass spectrometry (IDMS) to reduce the bias in the quantitative analysis of a target analyte present in a limited quantity in human plasma. Based on a Waters I-Class LC system, the DMHC 2D-LC system was operated in one- and two-dimensional modes to facilitate the determination of heart-cutting time and the efficient trapping of the target LC eluate. Experiments to determine the feasibility of coupling with IDMS were performed with triple quadrupole mass spectrometry using folic acid standards and/or 13C5-folic acid. To validate the performance of the DMHC 2D-LC/IDMS system on a complex sample, human plasma was analyzed for folic acid and the result was compared with that obtained using conventional single-column LC. The total run time of the DMHC 2D-LC system was 20 min, the same as that of the single-column LC system. The peak profile of the spiked 13C5-folic acid obtained with single-column LC/MS was affected by matrix effects, but resolved with DMHC 2D-LC/MS, thus improving the accuracy of the analysis. The DMHC 2D-LC/IDMS system showed reliable performance in analyzing the target analyte in human plasma, eliminating matrix effects and saving analysis time. 相似文献
13.
Troy A. Lowe Martin R. L. Paine David L. Marshall Larry A. Hick Jenny A. Boge Philip J. Barker Stephen J. Blanksby 《Journal of mass spectrometry : JMS》2010,45(5):486-495
Hindered amine light stabilisers (HALS) are the most effective antioxidants currently available for polymer systems in post‐production, in‐service applications, yet the mechanism of their action is still not fully understood. Structural characterisation of HALS in polymer matrices, particularly the identification of structural modifications brought about by oxidative conditions, is critical to aid mechanistic understanding of the prophylactic effects of these molecules. In this work, electrospray ionisation tandem mass spectrometry (ESI‐MS/MS) was applied to the analysis of a suite of commercially available 2,2,6,6‐tetramethylpiperidine‐based HALS. Fragmentation mechanisms for the [M + H]+ ions are proposed, which provide a rationale for the product ions observed in the MS/MS and MS3 mass spectra of N‐H, N‐CH3, N‐C(O)CH3 and N‐OR containing HALS (where R is an alkyl substituent). A common product ion at m/z 123 was identified for the group of antioxidants containing N‐H, N‐CH3 or N‐C(O)CH3 functionality, and this product ion was employed in precursor ion scans on a triple quadrupole mass spectrometer to identify the HALS species present in a crude extract from of a polyester‐based coil coating. Using MS/MS, two degradation products were unambiguously identified. This technique provides a simple and selective approach to monitoring HALS structures within complex matrices. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
14.
Goenaga-Infante H Sturgeon R Turner J Hearn R Sargent M Maxwell P Yang L Barzev A Pedrero Z Cámara C Díaz Huerta V Fernández Sánchez ML Sanz-Medel A Emese K Fodor P Wolf W Goldschmidt R Vacchina V Szpunar J Valiente L Huertas R Labarraque G Davis C Zeisler R Turk G Rizzio E Mackay LG Myors RB Saxby DL Askew S Chao W Jun W 《Analytical and bioanalytical chemistry》2008,390(2):629-642
Results of an international intercomparison study (CCQM-P86) to assess the analytical capabilities of national metrology institutes
(NMIs) and selected expert laboratories worldwide to accurately quantitate the mass fraction of selenomethionine (SeMet) and
total Se in pharmaceutical tablets of selenised-yeast supplements (produced by Pharma Nord, Denmark) are presented. The study,
jointly coordinated by LGC Ltd., UK, and the Institute for National Measurement Standards, National Research Council of Canada
(NRCC), was conducted under the auspices of the Comité Consultatif pour la Quantité de Matière (CCQM) Inorganic Analysis Working
Group and involved 15 laboratories (from 12 countries), of which ten were NMIs. Apart from a protocol for determination of
moisture content and the provision of the certified reference material (CRM) SELM-1 to be used as the quality control sample,
no sample preparation/extraction method was prescribed. A variety of approaches was thus used, including single-step and multiple-step
enzymatic hydrolysis, enzymatic probe sonication and hydrolysis with methanesulfonic acid for SeMet, as well as microwave-assisted
acid digestion and enzymatic probe sonication for total Se. For total Se, detection techniques included inductively coupled
plasma (ICP) mass spectrometry (MS) with external calibration, standard additions or isotope dilution MS (IDMS), inductively
coupled plasma optical emission spectrometry , flame atomic absorption spectrometry and instrumental neutron activation analysis.
For determination of SeMet in the tablets, five NMIs and three academic/institute laboratories (of a total of five) relied
upon measurements using IDMS. For species-specific IDMS measurements, an isotopically enriched standard of SeMet (76Se-enriched SeMet) was made available. A novel aspect of this study relies on the approach used to distinguish any errors
which arise during analysis of a SeMet calibration solution from those which occur during analysis of the matrix. To help
those participants undertaking SeMet analysis to do this, a blind sample in the form of a standard solution of natural abundance
SeMet in 0.1 M HCl (with an expected value of 956 mg kg−1 SeMet) was provided. Both high-performance liquid chromatography (HPLC)–ICP-MS or gas chromatography (GC)–ICP-MS and GC-MS
techniques were used for quantitation of SeMet. Several advances in analytical methods for determination of SeMet were identified,
including the combined use of double IDMS with HPLC-ICP-MS following extraction with methanesulfonic acid and simplified two-step
enzymatic hydrolysis with protease/lipase/driselase followed by HPLC-ICP-IDMS, both using a species-specific IDMS approach.
Overall, satisfactory agreement amongst participants was achieved; results averaged 337.6 mg kg−1 (n = 13, with a standard deviation of 9.7 mg kg−1) and 561.5 mg kg−1(n = 11, with a standard deviation of 44.3 mg kg−1) with median values of 337.6 and 575.0 mg kg−1 for total Se and SeMet, respectively. Recovery of SeMet from SELM-1 averaged 95.0% (n = 9). The ability of NMIs and expert laboratories worldwide to deliver accurate results for total Se and SeMet in such materials
(selensied-yeast tablets containing approximately 300 mg kg−1 Se) with 10% expanded uncertainty was demonstrated. The problems addressed in achieving accurate quantitation of SeMet in
this product are representative of those encountered with a wide range of organometallic species in a number of common matrices.
Figure Looking into the quantitative speciation of selenium in pharmaceutical supplements Photo courtesy of LGC. 相似文献
15.
Chrystelle Bancon‐Montigny Lu Yang Ralph E. Sturgeon Vanessa Colombini Zoltn Mester 《应用有机金属化学》2004,18(2):57-64
Isotopically enriched CH3198HgCl (MeHgCl) has been synthesized from commercially available elemental 198Hg (96% isotopic purity). Elemental mercury is first converted to HgCl2 and subsequently reacted with methylcobalamin to produce MeHgCl. The resulting MeHgCl is isolated from the reaction mixture by successive extractions with toluene and dried over Na2SO4. The product structure was verified using gas chromatography–mass spectrometry (GC–MS) and the isotopic composition was determined by GC–inductively coupled plasma MS. The yield obtained is 99%. The proposed method allows preparation of milligram quantities of MeHgCl in one step, minimizing the cost of this synthesis. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
16.
A new method was proposed for the accurate determination of mercury in cosmetic samples based on isotopic dilution (ID)-photochemical vapor generation (PVG)-inductively coupled plasma mass spectrometry (ICP MS) measurement. Cosmetic samples were directly dissolved in formic acid solution and subsequently subjected to PVG for the reduction of mercury into vapor species following by ICP MS detection. Therefore, the risks of analyte contamination and loss were avoided. Highly enriched 201Hg isotopic spike is added to cosmetics and the isotope ratios of 201Hg/202Hg were measured for the quantitation of mercury. With ID calibration, the influences originating from sample matrixes for the determination of mercury in cosmetic samples have been efficiently eliminated. The effects of several experimental parameters, such as the concentration of the formic acid, and the flow rates of carrier gas and sample were investigated. The method provided good reproducibility and the detection limits were found to be 0.6 pg mL−1. Finally, the developed method was successfully applied for the determination of mercury in six cosmetic samples and a spike test was performed to verify the accuracy of the method. 相似文献
17.
The hydrolysis of CH3Hg+ was studied potentiometrically in NaClO4 media in the range 0.1–3.0 mol dm−3 ionic strength at 25 °C. Evaluation of data with the non‐linear least‐squares computer programs BSTAC and STACO led us to propose the formation of CH3HgOH and (CH3Hg)2OH+ species. The stoichiometric stability constants obtained for the two species at the different ionic strengths were correlated by means of Modified Bromley Methodology (MBM) to obtain the corresponding thermodynamic equilibrium constants, as well as the interaction parameters of the soluble species. This is the first of a series of potentiometric studies on the different equilibria of methylmercury with the majority of ions present in natural waters in order to simulate the behaviour of methylmercury in sea and estuary waters. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
18.
Qingyang Liu 《Microchemical Journal》2010,95(2):255-258
A novel method based on photo-induced chemical vapor generation (CVG) as interface to on-line coupled Hg-cysteine ion chromatograpy (IC) with atomic fluorescence spectrometry (AFS) was developed for rapid determination of methylmercury (MHg) in seafood. Separation of inorganic mercury (Hg2+) and methylmercury(CH3Hg+) was accomplished on a Hamilton PRP X-200 polymer-based exchange column with a mobile of 3% acetonitrile, 1% (w/w) L-cysteine and 20 mmol L− 1 pyridine and 160 mmol L− 1 formic acid, at pH 2.4 within 7 min. Once separated, both species are reduced by formic acid in mobile phase under UV radiation to convert Hg0 on-line, which is subsequently swept (by argon carrier gas) into an atomic fluorescence spectrometry (AFS) for measurement. Under the optimized experiment conditions, the detection limits (as Hg), based on three times the standard deviation of a standard solution, were found to be 0.1 ng mL− 1 for mercury and 0.08 ng mL− 1 for methylmercury, with an injection volume of 100 μL. The developed method was validated by determination of certified reference material DORM-2 and was further applied in determination of seafood samples. 相似文献
19.
提出了一种适用于微量气体定量分析的大小球三步同位素稀释质谱法,并给出其实验模型和不确定度理论分析结果。通过引入三步稀释过程,不涉及稀释剂的纯度、丰度、添加质量等方面的数据,仅需测定各步稀释剂质量之比,在其中的两步反稀释过程中使用了基标准纯物质,从而使微量气体的定量分析结果可溯源至基标准纯物质。该方法解决了已有同位素稀释质谱法在微量气体定量分析中的难题。 相似文献
20.
Ángel Castillo Emma Gracia-Lor Antoni Francesc Roig-Navarro Juan Vicente Sancho Pablo Rodríguez-González J. Ignacio García Alonso 《Analytica chimica acta》2013
Isotope dilution mass spectrometry (IDMS) based on isotope pattern deconvolution (IPD) has been applied here to MS/MS (QqQ) in order to carry out the quantification and confirmation of organic compounds in complex matrix water samples without the use of a methodological IDMS calibration graph. In this alternative approach, the isotope composition of the spiked sample is measured after fragmentation by SRM and deconvoluted into its constituting components (molar fractions of natural abundance and labeled compound) by multiple linear regression (IPD). The procedure has been evaluated for the determination of the pharmaceutical diclofenac in effluent and influent urban wastewaters and fortified surface waters by UHPLC (ESI) MS/MS using diclofenac-d4 as labeled compound. Calculations were performed acquiring a part and the whole fragment cluster ion, achieving in all cases recoveries within 90–110% and coefficients of variation below 5% for all water samples tested. In addition, potential false negatives arising from the presence of diclofenac-d2 impurities in the labeled compound were avoided when the proposed approach was used instead of the most usual IDMS calibration procedure. The number of SRM transitions measured was minimized to three to make possible the application of this alternative technique in routine multi-residue analysis. 相似文献