@article{MTMT:30393701, title = {Describing chemical transformations in multiple spiking isotope dilution: Fundamental aspects and definitions}, url = {https://m2.mtmt.hu/api/publication/30393701}, author = {Meija, J. and Ouerdane, L. and Mester, Zoltán}, doi = {10.1039/b814388a}, journal-iso = {ANALYST}, journal = {ANALYST}, volume = {134}, unique-id = {30393701}, issn = {0003-2654}, abstract = {Currently, several mathematical methods exist to address simultaneous species formation and degradation using multiple spiking isotope dilution mass spectrometry. While all of these strategies have been compared numerically, comparison of the underlying principles is lacking. Owing to recent interest in using the species inter-conversion factors, mainly to study the quality of analytical methods, this manuscript reviews the mathematical logic and inconsistencies of the existing double or triple spiking isotope dilution models. Systematic terminology is also introduced to clarify the species inter-conversion coefficient definitions. © The Royal Society of Chemistry.}, year = {2009}, eissn = {1364-5528}, pages = {466-471}, orcid-numbers = {Mester, Zoltán/0000-0002-2377-2615} } @article{MTMT:30393700, title = {Isotope scrambling and error magnification in multiple-spiking isotope dilution}, url = {https://m2.mtmt.hu/api/publication/30393700}, author = {Meija, J. and Ouerdane, L. and Mester, Zoltán}, doi = {10.1007/s00216-009-2619-x}, journal-iso = {ANAL BIOANAL CHEM}, journal = {ANALYTICAL AND BIOANALYTICAL CHEMISTRY}, volume = {394}, unique-id = {30393700}, issn = {1618-2642}, abstract = {The purpose of performing multiple spiking isotope dilution is to quantify interconverting substances. This feature has been utilized in analytical chemistry now for more than a decade. In this manuscript we show that the interconversion of analytes is inevitably accompanied by the gradual loss of information that can be extracted from the isotope patterns. Therefore, any corrections for analyte interconversion are performed at the expense of the precision of the obtained amount of interconverting analytes. Consequently, there is a natural, predictable limit to the applicability of multiple-spiking isotope dilution methods that can be summarized into a simple equation. © Crown copyright in right of Canada 2009.}, keywords = {ISOTOPES; Monte Carlo; Monte Carlo; UNCERTAINTY; UNCERTAINTY; dilution; Monte Carlo methods; Error propagation; Error propagation; Isotope dilution; Isotope dilution; Isotope scrambling; Isotope scrambling; Multiple spiking; Multiple spiking}, year = {2009}, eissn = {1618-2650}, pages = {199-205}, orcid-numbers = {Mester, Zoltán/0000-0002-2377-2615} } @article{MTMT:30393699, title = {General equation for multiple spiking isotope dilution mass spectrometry}, url = {https://m2.mtmt.hu/api/publication/30393699}, author = {Ouerdane, L. and Mester, Zoltán and Meija, J.}, doi = {10.1021/ac900205b}, journal-iso = {ANAL CHEM}, journal = {ANALYTICAL CHEMISTRY}, volume = {81}, unique-id = {30393699}, issn = {0003-2700}, abstract = {Isotope dilution is a well-known primary ratio method of quantitative analysis that yields good-quality metrological results. Many equations have been proposed to calculate the amount of substance from the isotope ratio measurements, and these have been used successfully for more than a half-century. Decades ago, isotope dilution equations were extended to correct for analyte formation during analysis, which is especially apparent in the analysis of methylmercury or chromium(VI). Considering only methods for the determination of these two analytes, many variables that are involved must be considered (for example, the extent of analyte formation, the number of isotopes monitored for each analyte, the number of substances, or the nature of mass spectra (elemental versus molecular)). To date, no master equation that can adequately address all of these aspects of the problem has been proposed. In this manuscript, we propose a general equation for isotope dilution.}, keywords = {ARTICLE; quantitative analysis; spike; Methyl mercury; Mass spectrometry; Mass spectrometry; ISOTOPES; quality control; isotope dilution assay; dilution; Chromium; mercury compounds; mathematical computing; Mass spectrometers; Analytes; Mass spectra; chromium 51; Master equations; Analyte; General equations; Methylmercury; Isotope dilutions; Isotope dilution mass spectrometry; Isotope-ratio measurements; Ratio method}, year = {2009}, eissn = {1520-6882}, pages = {5075-5079}, orcid-numbers = {Mester, Zoltán/0000-0002-2377-2615} } @article{MTMT:1466218, title = {Species specific IDMS for accurate quantification of carboplatin in urine by LC-ESI-TOFMS and LC-ICP-QMS}, url = {https://m2.mtmt.hu/api/publication/1466218}, author = {Koellensperger, G and Stefánka, Zsolt and Meelich, K and Galanski, M and Keppler, B K and Stingeder, G and Hann, S}, doi = {10.1039/b708541a}, journal-iso = {J ANAL ATOM SPECTROM}, journal = {JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY}, volume = {23}, unique-id = {1466218}, issn = {0267-9477}, abstract = {For the first time, 194Pt isotopically enriched carboplatin has been synthesized, serving for species specific isotope dilution analysis. Carboplatin was determined in urine, implementing both LC-ICP-QMS and LC-ESI-TOFMS. Hence, a separation method was applied, compatible with both ICP-QMS and ESI-MS detection. IDMS quantification was evaluated in terms of measurement uncertainty, comparing the two mass spectrometric detection methods. The procedural limits of detection of HPLC-ICP-QMS and HPLC-ESI-TOFMS were 0.1 ng g-1 and 15 ng g-1, respectively. Both methodologies were successfully applied to the quantification of carboplatin in the urine of a chemotherapy patient. The obtained carboplatin concentrations agreed within their uncertainties. Uncertainty budgeting calculations revealed that the accuracy of quantification was primarily limited by the precision of isotope ratio measurement, governing the determination of the ratios Rx, Ry and Rb of the IDMS equation. For ICP-QMS, a total combined uncertainty of 5.7% (coverage factor 2) was assessed. In accordance to the impaired precision of blend ratio determination in ESI-TOFMS (precision of 5% compared to 1% in ICP-QMS), this method revealed a total combined uncertainty of 23%. © The Royal Society of Chemistry 2008.}, year = {2008}, eissn = {1364-5544}, pages = {29-36} } @article{MTMT:30393708, title = {Paradigms in isotope dilution mass spectrometry for elemental speciation analysis}, url = {https://m2.mtmt.hu/api/publication/30393708}, author = {Meija, J. and Mester, Zoltán}, doi = {10.1016/j.aca.2007.11.050}, journal-iso = {ANAL CHIM ACTA}, journal = {ANALYTICA CHIMICA ACTA}, volume = {607}, unique-id = {30393708}, issn = {0003-2670}, abstract = {Isotope dilution mass spectrometry currently stands out as the method providing results with unchallenged precision and accuracy in elemental speciation. However, recent history of isotope dilution mass spectrometry has shown that the extent to which this primary ratio measurement method can deliver accurate results is still subject of active research. In this review, we will summarize the fundamental prerequisites behind isotope dilution mass spectrometry and discuss their practical limits of validity and effects on the accuracy of the obtained results. This review is not to be viewed as a critique of isotope dilution; rather its purpose is to highlight the lesser studied aspects that will ensure and elevate current supremacy of the results obtained from this method. Crown Copyright © 2007.}, keywords = {EXTRACTION; review; Chemistry; Measurement; priority journal; Mass spectrometry; Mass spectrometry; Mass spectrometry; Mass spectrometry; ISOTOPES; ISOTOPES; Reproducibility of Results; isotope dilution assay; dilution; dilution; accuracy; mathematical computing; validation process; isotope; Radioisotope Dilution Technique; Indicator Dilution Techniques; Isotope dilution; Isotope dilution; Elemental speciation; Elemental speciation; Isotopic equilibration; Isotopic equilibration}, year = {2008}, eissn = {1873-4324}, pages = {115-125}, orcid-numbers = {Mester, Zoltán/0000-0002-2377-2615} } @article{MTMT:30393716, title = {Calculations of double spike isotope dilution results revisited}, url = {https://m2.mtmt.hu/api/publication/30393716}, author = {Meija, J. and Yang, L. and Caruso, J.A. and Mester, Zoltán}, doi = {10.1039/b607823k}, journal-iso = {J ANAL ATOM SPECTROM}, journal = {JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY}, volume = {21}, unique-id = {30393716}, issn = {0267-9477}, abstract = {The use of isotope pattern deconvolution analysis is proposed to simplify the double spiking species-specific isotope dilution result calculations when inter-conversion might occur. A detailed example is given for the determination of Cr(iii)/Cr(vi) in yeast by isotope dilution-HPLC-ICP-MS. The results are in exact agreeent with the conventional isotope dilution calculations. © The Royal Society of Chemistry 2006.}, keywords = {YEAST; high performance liquid chromatography; Mass spectrometry; ISOTOPES; Inductively coupled plasma; Convolution; Isotope dilution; Deconvolution analysis}, year = {2006}, eissn = {1364-5544}, pages = {1294-1297}, orcid-numbers = {Mester, Zoltán/0000-0002-2377-2615} } @article{MTMT:1721087, title = {Certification of a new selenized yeast reference material (SELM-1) for methionine, Selenomethionine and total selenium content and its use in an intercomparison exercise for quantifying these analytes}, url = {https://m2.mtmt.hu/api/publication/1721087}, author = {Mester, Zoltán and Willie, S and Yang, Lu and Sturgeon, R and Caruso, J and Fernandez, M and Fodor, Péter and Goldschmidt, R and Goenaga-Infante, H and Lobinski, R and Maxwell, P and McSeehy, S and Polatajko, A and Sadi, B and Sanz-Medel, A and Scriver, C and Szpunar, J and Wahlen, R and Wolf, W}, doi = {10.1007/s00216-006-0338-0}, journal-iso = {ANAL BIOANAL CHEM}, journal = {ANALYTICAL AND BIOANALYTICAL CHEMISTRY}, volume = {385}, unique-id = {1721087}, issn = {1618-2642}, year = {2006}, eissn = {1618-2650}, pages = {168-180}, orcid-numbers = {Mester, Zoltán/0000-0002-2377-2615} } @article{MTMT:30393730, title = {Determination of methionine and selenomethionine in selenium-enriched yeast by species-specific isotope dilution with liquid chromatography-mass spectrometry and inductively coupled plasma mass spectrometry detection}, url = {https://m2.mtmt.hu/api/publication/30393730}, author = {McSheehy, S. and Yang, L. and Sturgeon, R. and Mester, Zoltán}, doi = {10.1021/ac048637e}, journal-iso = {ANAL CHEM}, journal = {ANALYTICAL CHEMISTRY}, volume = {77}, unique-id = {30393730}, issn = {0003-2700}, abstract = {Selenomethionine (SeMet) and methionine (Met), liberated by acid hydrolysis of selenium-enriched yeast, were quantified by liquid chromatography-mass spectrometry (LC/MS) using standard additions calibrations as well as isotope dilution (ID) based on species-specific 13C-enriched spikes. LC inductively coupled plasma mass spectrometry (ICPMS) was also employed for the quantification of SeMet, and 74Se-enriched SeMet was used for ID calibration. The results were evaluated to ascertain the feasibility of using these methods in a campaign to certify selenized yeast Good agreement was found between the methods, which, when averaged, gave concentrations of 5482.2 ± 101 and 3256.9 ± 217.4 μg/g for Met and SeMet, respectively. This corresponds to a 1.68:1 Met-to-SeMet ratio in the yeast Quantification by ID LC/MS and LC ICPMS yields the most precise sets of results with relative standard deviations in the range 0.5-1.3% (n = 6). A total selenium concentration of 2064.6 ± 45.4 μg/g was obtained for this yeast material. The extraction efficiency and a mass balance budget were determined. Acid hydrolysis liberated 81.0% of the total selenium present SeMet comprised 79.0% of the extracted selenium and 63.9% of the total selenium present in the yeast.}, keywords = {EXTRACTION; ARTICLE; YEAST; YEAST; HYDROLYSIS; Carbon Isotopes; liquid chromatography; liquid chromatography; nonhuman; Species Specificity; species difference; quantitative analysis; CALIBRATION; Chromatography, Liquid; Mass spectrometry; Mass spectrometry; Mass spectrometry; ISOTOPES; synthesis; isotope dilution assay; analytic method; Selenium; Selenium; Selenium; selenomethionine; selenomethionine; selenomethionine; METHIONINE; METHIONINE; METHIONINE; atomic emission spectrometry; Inductively coupled plasma; carbon 13; Yeasts; acid hydrolysis}, year = {2005}, eissn = {1520-6882}, pages = {344-349}, orcid-numbers = {Mester, Zoltán/0000-0002-2377-2615} } @article{MTMT:1390069, title = {Methylmercury in tuna: demonstrating measurement capabilities and evaluating comparability of results worldwide from the CCQM P-39 comparison}, url = {https://m2.mtmt.hu/api/publication/1390069}, author = {Quetel, CR and Snell, JP and Aregbe, Y and Abrankó, László and Jókainé Szatura, Zsuzsa and Brunori, C and Morabito, R and Hagan, W and Azemard, S and Wyse, E and Fajon, V and Horvat, M and Logar, M and Donard, OFX and Krupp, E and Entwisle, J and Hearn, R and Schantz, M and Inagaki, K and Takatsu, A and Grinberg, P and Willlie, S and Dimock, B and Hintelmann, H and Zhu, J and Gonzalez, EB and Centineo, G and Alonso, JEG and Sanz-Medel, A and Bjorn, E}, doi = {10.1039/b505368d}, journal-iso = {J ANAL ATOM SPECTROM}, journal = {JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY}, volume = {20}, unique-id = {1390069}, issn = {0267-9477}, abstract = {Six metrology institutes (NMIs) representing at the Comite 'International des Poids et Mesures (CIPM) 4 Member States of the Metre Convention and 2 international organisations, and 8 "expert'' laboratories selected outside CIPM have compared their capabilities to quantitatively measure methylmercury (MeHg) in a prepared tuna material containing approximately 4.3 mg kg(-1) Hg. This comparison was the object of the CIPM - Comite Consultatif pour la Quantite de Matiere (CCQM) Pilot Study 39, organised by the Institute for Reference Materials and Measurements (IRMM), from the European Commission - Joint Research Centre. Beside the test material itself, a bottle of the BCR-464 tuna Certified Reference Material (CRM) and an ampoule of IRMM-670, a 202 Hg isotope enriched MeHg candidate isotopic CRM, were distributed to all participants, who were free to apply the measurement strategy of their choice. Four, including 1 NMI, relied on external calibration or the method of standard additions, whereas the other 10 implemented an isotope dilution mass spectrometry (IDMS) approach and chose to use the IRMM-670 for their measurements. Alkaline digestion at room temperature ( with manual shaking) or high temperature ( under sonication, oven or hot plate conditions) was employed by most participants, with hydrochloric acid leaching the second most popular choice. Alkylation ( 4 phenylations, 4 ethylations and 3 propylations) in the aqueous phase was preferred by a large majority over butylation by the Grignard reaction. All participants were requested to estimate the uncertainty associated with their results and 9 out of 14 stated relative combined uncertainties below 6% (k = 2). Despite this apparent consensus, the perception of which factor caused the largest contribution to this estimation differed among participants because of the differences in the analytical methodologies deployed but also because of wide differences of the concepts of uncertainty estimation. The mixture mode' (MM) median, calculated also from the measurement uncertainties stated by the participants, was 1.967 +/- 0.204 x 10(-5) mol kg(-1) (95% confidence). Twelve of the results were re-grouped within a range of less than 0.3 x 10(-5) mol kg(-1) (MM median = 1.967 +/- 0.162 x 10(-5) mol kg(-1), 95% confidence): they nearly all (1 exception) overlapped with each other within k = 2 stated uncertainties. For the other 2 results the uncertainty seemed to have been particularly underestimated as they lay, respectively, at more than 20% above and less than - 40% below the overall average. The relative standard deviation of the results of 9 laboratories out of the 10 that applied IDMS was about 2.6%. It can be assumed from the degree of equivalence shown by 12 out of 14 study participants that, at present, laboratories worldwide are potentially able to supply accurate results for MeHg in fish-type matrices ( containing about 2 x 10(-5) mol kg(-1)) within +/- 10% uncertainty. This encouraging outcome permitted scheduling of a follow-up CCQM-K43 key comparison for a lower MeHg content level in salmon tissues.}, year = {2005}, eissn = {1364-5544}, pages = {1058-1066}, orcid-numbers = {Abrankó, László/0000-0002-0160-7280} } @article{MTMT:1466221, title = {Investigation of the reaction of cisplatin with methionine in aqueous media using HPLC-ICP-DRCMS}, url = {https://m2.mtmt.hu/api/publication/1466221}, author = {Stefánka, Zsolt and Hann, S and Koellensperger, G and Stingeder, G}, doi = {10.1039/b402028f}, journal-iso = {J ANAL ATOM SPECTROM}, journal = {JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY}, volume = {19}, unique-id = {1466221}, issn = {0267-9477}, abstract = {The reaction of cisplatin with methionine was studied by high performance ion chromatography coupled to inductively coupled plasma mass spectrometry equipped with dynamic reaction cell technique (HPLC-ICP-DRCMS) at two different cisplatin concentrations simulating chemotherapy conditions and waste water levels. The reaction of cisplatin with methionine was monitored over a period of 16 h. Accurate quantification of all platinum containing compounds was achieved via species unspecific on-line isotope dilution mass spectrometry. A limit of detection (LOD) of 0.31, 0.25, 3.83, 1.07, 0.56, 0.82 and 2.38 μg L -1 was calculated at m/z 194 for cisplatin, monoaquacisplatin, diaquacisplatin and the four platinum containing adducts, respectively. Stoichiometric platinum/sulfur ratios were assessed for characterization of the four adducts using ICP-DRCMS detection employing oxygen as reaction gas. An excellent sulfur detection limit of 1.30 μg L-1 could be achieved by HPLC-ICP-DRCMS (20 μL injection volume). At high cisplatin levels (0.6 mmol L-1) typical in chemotherapy, it was found that adducts show different kinetic behavior depending on the two investigated chloride levels (1.5 and 150 mmol L-1). Moreover, the reaction course depended on the concentration of the reactants, i.e. cisplatin and methionine. Experiments simulating possible reactions of the compounds in the aquatic environment revealed that at low μmol L-1 levels no adduct formation occurred. Finally, the stability of the four adducts potentially formed during chemotherapy was investigated representing the dilution of patient urine via hospital waste water. A considerable amount of highly active monoaquacisplatin was formed, indicating a reversal of detoxification reaction pathways of the human body. © The Royal Society of Chemistry 2004.}, year = {2004}, eissn = {1364-5544}, pages = {894-898} } @article{MTMT:21785825, title = {Comparison of extraction methods for quantitation of methionine and selenomethionine in yeast by species specific isotope dilution gas chromatography-mass spectrometry}, url = {https://m2.mtmt.hu/api/publication/21785825}, author = {Yang, L and Sturgeon, R E and McSheehy, S and Mester, Zoltán}, doi = {10.1016/j.chroma.2004.09.018}, journal-iso = {J CHROMATOGR A}, journal = {JOURNAL OF CHROMATOGRAPHY A}, volume = {1055}, unique-id = {21785825}, issn = {0021-9673}, year = {2004}, eissn = {1873-3778}, pages = {177-184}, orcid-numbers = {Mester, Zoltán/0000-0002-2377-2615} } @article{MTMT:21577729, title = {Determination of selenomethionine in yeast using CNBr derivatization and species specific isotope dilution GC ICP-MS and GC-MS}, url = {https://m2.mtmt.hu/api/publication/21577729}, author = {Yang, L and Sturgeon, R E and Wolf, W R and Goldschmidt, R J and Mester, Zoltán}, doi = {10.1039/b410543e}, journal-iso = {J ANAL ATOM SPECTROM}, journal = {JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY}, volume = {19}, unique-id = {21577729}, issn = {0267-9477}, year = {2004}, eissn = {1364-5544}, pages = {1448-1453}, orcid-numbers = {Mester, Zoltán/0000-0002-2377-2615} } @article{MTMT:30393734, title = {Determination of methionine and selenomethionine in yeast by species-specific isotope dilution GC/MS}, url = {https://m2.mtmt.hu/api/publication/30393734}, author = {Yang, L. and Mester, Zoltán and Sturgeon, R.E.}, doi = {10.1021/ac049475p}, journal-iso = {ANAL CHEM}, journal = {ANALYTICAL CHEMISTRY}, volume = {76}, unique-id = {30393734}, issn = {0003-2700}, abstract = {A method for the simultaneous determination of methionine (Met) and selenomethionine (SeMet) in yeast using species-specific isotope dilution (ID) gas chromatography/mass spectrometry (GC/MS) is described. Samples were digested by refluxing for 16 h with 4 M methane-sulfonic acid. Analytes were derivatized with methyl chloroformate and extracted into chloroform for GC/MS analysis. In addition to use of commercially available 13C-enriched Met and SeMet spikes for species specific ID analysis, a 74Se-enriched SeMet spike was also available for comparison of results. In selective ion monitoring mode, the intensities of ions at m/z 221, 222, 269, 270, and 263 were used to calculate the 221/222, 269/270, and 269/263 ion ratios for quantification of Met and SeMet. Concentrations of 5959 ± 33 and 3404 ± 12 μg g -1 (one standard deviation, n = 6) with relative standard deviations of 0.55 and 0.36% for Met and SeMet, respectively, were obtained using 13C-enriched spikes. A concentration of 3417 ± 8 μg g -1 (one standard deviation, n = 6) was obtained using the 74Se-enriched SeMet spike. The concentration of SeMet measured in the yeast is equivalent to 66.43 ± 0.24% of total Se and 30.31 ± 0.11% of total Met is in the form of SeMet. Method detection limits (three times the standard deviation) of 3.4 and 1.0 μg g-1 were estimated for Met and SeMet, respectively, based on a 0.25-g subsample of yeast with 1 mL of extract used for derivatization. A similar concentration of 5930 ± 29 μg g-1 (one standard deviation, n = 4) for Met and a lower concentration of 2787 ± 49 μg g-1 (one standard deviation, n = 4) for SeMet were obtained for this yeast sample using species-specific ID analysis based on GC/MS with 13C-enriched Met and SeMet spikes when a 2-h open microwave digestion approach using 8 M methanesulfonic acid was used.}, keywords = {DERIVATIVES; EXTRACTION; ARTICLE; YEAST; Carbon Isotopes; nonhuman; Species Specificity; Mass spectrometry; Mass spectrometry; ISOTOPES; METHANE; isotope dilution assay; analytic method; DERIVATIZATION; Gas chromatography; Gas chromatography; selenomethionine; selenomethionine; selenomethionine; METHIONINE; METHIONINE; Concentration (process); concentration (parameters); Inorganic acids; CHLOROFORM; carbon 13; Gas Chromatography-Mass Spectrometry; Mesylates; Yeasts; FLUXES; Indicator Dilution Techniques; Refluxing; ion monitoring; Sulfonic acid; Isotope dilution; mesylic acid; 1,1,1 trichloroethane}, year = {2004}, eissn = {1520-6882}, pages = {5149-5156}, orcid-numbers = {Mester, Zoltán/0000-0002-2377-2615} }