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Steven J Soldin - One of the best experts on this subject based on the ideXlab platform.

  • Isotope Dilution tandem mass spectrometric method for t4 t3
    Clinica Chimica Acta, 2004
    Co-Authors: Nadia Soukhova, Offie P Soldin, Steven J Soldin
    Abstract:

    Abstract Background : The thyroid hormones thyroxine (T4) and 3,5,3′-triidothyronine (T3) are essential for regulating a number of biological processes, including growth, neurodevelopment, carbohydrate metabolism, oxygen consumption and protein synthesis. Immunoassays are the current methods for thyroid hormone measurement and suffer from a lack of specificity. Our objective was to simultaneously measure T4 and T3 using Isotope Dilution tandem mass spectrometry within a single run. To compare the results obtained by this MS/MS method with those obtained by an immunoassay procedure on the same samples (DPC Immulite for T3, Diagnostics Product, and Dade RxL Dimension for T4, Dade-Behring). Methods : An API-3000 tandem mass spectrometer (SCIEX, Toronto, Canada) equipped with TurboIonSpray and Shimadzu HPLC system was used employing Isotope Dilution with deuterium-labeled internal standard ( l -thyroxin-d 2 ). The method requires 100 μl of serum and involves addition of internal standard, precipitation of proteins with methanol and injection of the supernatant onto a C-18 column. After washing, the switch valve is activated and T4 and T3 eluted using a methanol gradient. T4 and T3 by immunoassay were performed using the Dade RxL Dimension and the DPC Immulite, respectively. Results and conclusions : An Isotope Dilution tandem mass spectrometry method for the simultaneous determination of total T4 and T3 in serum is described which is accurate, specific, precise (%CVs 3.5–9.0), simple and fast (

  • Isotope Dilution tandem mass spectrometric method for T4/T3.
    Clinica Chimica Acta, 2004
    Co-Authors: Nadia Soukhova, Offie P Soldin, Steven J Soldin
    Abstract:

    Abstract Background : The thyroid hormones thyroxine (T4) and 3,5,3′-triidothyronine (T3) are essential for regulating a number of biological processes, including growth, neurodevelopment, carbohydrate metabolism, oxygen consumption and protein synthesis. Immunoassays are the current methods for thyroid hormone measurement and suffer from a lack of specificity. Our objective was to simultaneously measure T4 and T3 using Isotope Dilution tandem mass spectrometry within a single run. To compare the results obtained by this MS/MS method with those obtained by an immunoassay procedure on the same samples (DPC Immulite for T3, Diagnostics Product, and Dade RxL Dimension for T4, Dade-Behring). Methods : An API-3000 tandem mass spectrometer (SCIEX, Toronto, Canada) equipped with TurboIonSpray and Shimadzu HPLC system was used employing Isotope Dilution with deuterium-labeled internal standard ( l -thyroxin-d 2 ). The method requires 100 μl of serum and involves addition of internal standard, precipitation of proteins with methanol and injection of the supernatant onto a C-18 column. After washing, the switch valve is activated and T4 and T3 eluted using a methanol gradient. T4 and T3 by immunoassay were performed using the Dade RxL Dimension and the DPC Immulite, respectively. Results and conclusions : An Isotope Dilution tandem mass spectrometry method for the simultaneous determination of total T4 and T3 in serum is described which is accurate, specific, precise (%CVs 3.5–9.0), simple and fast (

Juris Meija - One of the best experts on this subject based on the ideXlab platform.

  • reducing the matrix effects in chemical analysis fusion of Isotope Dilution and standard addition methods
    Metrologia, 2016
    Co-Authors: Enea Pagliano, Juris Meija
    Abstract:

    The combination of Isotope Dilution and mass spectrometry has become an ubiquitous tool of chemical analysis. Often perceived as one of the most accurate methods of chemical analysis, it is not without shortcomings. Current Isotope Dilution equations are not capable of fully addressing one of the key problems encountered in chemical analysis: the possible effect of sample matrix on measured Isotope ratios. The method of standard addition does compensate for the effect of sample matrix by making sure that all measured solutions have identical composition. While it is impossible to attain such condition in traditional Isotope Dilution, we present equations which allow for matrix-matching between all measured solutions by fusion of Isotope Dilution and standard addition methods.

  • Blank Correction in Isotope Dilution.
    Analytical chemistry, 2015
    Co-Authors: Enea Pagliano, Zoltan Mester, Juris Meija
    Abstract:

    A novel method for compensation of the procedural blank in Isotope Dilution is presented. This method, entitled “blank-matching”, copes with the blank through experimental design. Both sample and calibration solutions are exposed to the same amount of isotopic standard and same procedural blank. The identical treatment of sample and calibrators eliminates the need for subtracting the procedural blank from the result obtained by Isotope Dilution. A further advantage of the method is that quantitation of the analyte in the procedural blank is not required. Blank-matching is simple and fast to implement, and it permits direct determination of results without further corrections. This aspect has an important metrological outcome: blank-matching Isotope Dilution can be considered a primary method of analysis that does not involve the procedural blank as a potential source of bias.

  • Calibration graphs in Isotope Dilution mass spectrometry.
    Analytica chimica acta, 2015
    Co-Authors: Enea Pagliano, Zoltan Mester, Juris Meija
    Abstract:

    Isotope-based quantitation is routinely employed in chemical measurements. Whereas most analysts seek for methods with linear theoretical response functions, a unique feature that distinguishes Isotope Dilution from many other analytical methods is the inherent possibility for a nonlinear theoretical response curve. Most implementations of Isotope Dilution calibration today either eliminate the nonlinearity by employing internal standards with markedly different molecular weight or they employ empirical polynomial fits. Here we show that the exact curvature of any Isotope Dilution curve can be obtained from three-parameter rational function, y = f(q) = (a0 + a1q)/(1 + a2q), known as the Pade[1,1] approximant. The use of this function allows eliminating an unnecessary source of error in Isotope Dilution analysis when faced with nonlinear calibration curves. In addition, fitting with Pade model can be done using linear least squares.

  • General equation for multiple spiking Isotope Dilution mass spectrometry
    Analytical Chemistry, 2009
    Co-Authors: L. Ouerdane, Zoltan Mester, Juris Meija
    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.

  • Describing chemical transformations in multiple spiking Isotope Dilution: fundamental aspects and definitions.
    The Analyst, 2008
    Co-Authors: Juris Meija, Laurent Ouerdane, Zoltan Mester
    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.

Zoltan Mester - One of the best experts on this subject based on the ideXlab platform.

  • Blank Correction in Isotope Dilution.
    Analytical chemistry, 2015
    Co-Authors: Enea Pagliano, Zoltan Mester, Juris Meija
    Abstract:

    A novel method for compensation of the procedural blank in Isotope Dilution is presented. This method, entitled “blank-matching”, copes with the blank through experimental design. Both sample and calibration solutions are exposed to the same amount of isotopic standard and same procedural blank. The identical treatment of sample and calibrators eliminates the need for subtracting the procedural blank from the result obtained by Isotope Dilution. A further advantage of the method is that quantitation of the analyte in the procedural blank is not required. Blank-matching is simple and fast to implement, and it permits direct determination of results without further corrections. This aspect has an important metrological outcome: blank-matching Isotope Dilution can be considered a primary method of analysis that does not involve the procedural blank as a potential source of bias.

  • Calibration graphs in Isotope Dilution mass spectrometry.
    Analytica chimica acta, 2015
    Co-Authors: Enea Pagliano, Zoltan Mester, Juris Meija
    Abstract:

    Isotope-based quantitation is routinely employed in chemical measurements. Whereas most analysts seek for methods with linear theoretical response functions, a unique feature that distinguishes Isotope Dilution from many other analytical methods is the inherent possibility for a nonlinear theoretical response curve. Most implementations of Isotope Dilution calibration today either eliminate the nonlinearity by employing internal standards with markedly different molecular weight or they employ empirical polynomial fits. Here we show that the exact curvature of any Isotope Dilution curve can be obtained from three-parameter rational function, y = f(q) = (a0 + a1q)/(1 + a2q), known as the Pade[1,1] approximant. The use of this function allows eliminating an unnecessary source of error in Isotope Dilution analysis when faced with nonlinear calibration curves. In addition, fitting with Pade model can be done using linear least squares.

  • General equation for multiple spiking Isotope Dilution mass spectrometry
    Analytical Chemistry, 2009
    Co-Authors: L. Ouerdane, Zoltan Mester, Juris Meija
    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.

  • Describing chemical transformations in multiple spiking Isotope Dilution: fundamental aspects and definitions.
    The Analyst, 2008
    Co-Authors: Juris Meija, Laurent Ouerdane, Zoltan Mester
    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.

  • paradigms in Isotope Dilution mass spectrometry for elemental speciation analysis
    Analytica Chimica Acta, 2008
    Co-Authors: Juris Meija, Zoltan Mester
    Abstract:

    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.

Nadia Soukhova - One of the best experts on this subject based on the ideXlab platform.

  • Isotope Dilution tandem mass spectrometric method for t4 t3
    Clinica Chimica Acta, 2004
    Co-Authors: Nadia Soukhova, Offie P Soldin, Steven J Soldin
    Abstract:

    Abstract Background : The thyroid hormones thyroxine (T4) and 3,5,3′-triidothyronine (T3) are essential for regulating a number of biological processes, including growth, neurodevelopment, carbohydrate metabolism, oxygen consumption and protein synthesis. Immunoassays are the current methods for thyroid hormone measurement and suffer from a lack of specificity. Our objective was to simultaneously measure T4 and T3 using Isotope Dilution tandem mass spectrometry within a single run. To compare the results obtained by this MS/MS method with those obtained by an immunoassay procedure on the same samples (DPC Immulite for T3, Diagnostics Product, and Dade RxL Dimension for T4, Dade-Behring). Methods : An API-3000 tandem mass spectrometer (SCIEX, Toronto, Canada) equipped with TurboIonSpray and Shimadzu HPLC system was used employing Isotope Dilution with deuterium-labeled internal standard ( l -thyroxin-d 2 ). The method requires 100 μl of serum and involves addition of internal standard, precipitation of proteins with methanol and injection of the supernatant onto a C-18 column. After washing, the switch valve is activated and T4 and T3 eluted using a methanol gradient. T4 and T3 by immunoassay were performed using the Dade RxL Dimension and the DPC Immulite, respectively. Results and conclusions : An Isotope Dilution tandem mass spectrometry method for the simultaneous determination of total T4 and T3 in serum is described which is accurate, specific, precise (%CVs 3.5–9.0), simple and fast (

  • Isotope Dilution tandem mass spectrometric method for T4/T3.
    Clinica Chimica Acta, 2004
    Co-Authors: Nadia Soukhova, Offie P Soldin, Steven J Soldin
    Abstract:

    Abstract Background : The thyroid hormones thyroxine (T4) and 3,5,3′-triidothyronine (T3) are essential for regulating a number of biological processes, including growth, neurodevelopment, carbohydrate metabolism, oxygen consumption and protein synthesis. Immunoassays are the current methods for thyroid hormone measurement and suffer from a lack of specificity. Our objective was to simultaneously measure T4 and T3 using Isotope Dilution tandem mass spectrometry within a single run. To compare the results obtained by this MS/MS method with those obtained by an immunoassay procedure on the same samples (DPC Immulite for T3, Diagnostics Product, and Dade RxL Dimension for T4, Dade-Behring). Methods : An API-3000 tandem mass spectrometer (SCIEX, Toronto, Canada) equipped with TurboIonSpray and Shimadzu HPLC system was used employing Isotope Dilution with deuterium-labeled internal standard ( l -thyroxin-d 2 ). The method requires 100 μl of serum and involves addition of internal standard, precipitation of proteins with methanol and injection of the supernatant onto a C-18 column. After washing, the switch valve is activated and T4 and T3 eluted using a methanol gradient. T4 and T3 by immunoassay were performed using the Dade RxL Dimension and the DPC Immulite, respectively. Results and conclusions : An Isotope Dilution tandem mass spectrometry method for the simultaneous determination of total T4 and T3 in serum is described which is accurate, specific, precise (%CVs 3.5–9.0), simple and fast (

Enea Pagliano - One of the best experts on this subject based on the ideXlab platform.

  • reducing the matrix effects in chemical analysis fusion of Isotope Dilution and standard addition methods
    Metrologia, 2016
    Co-Authors: Enea Pagliano, Juris Meija
    Abstract:

    The combination of Isotope Dilution and mass spectrometry has become an ubiquitous tool of chemical analysis. Often perceived as one of the most accurate methods of chemical analysis, it is not without shortcomings. Current Isotope Dilution equations are not capable of fully addressing one of the key problems encountered in chemical analysis: the possible effect of sample matrix on measured Isotope ratios. The method of standard addition does compensate for the effect of sample matrix by making sure that all measured solutions have identical composition. While it is impossible to attain such condition in traditional Isotope Dilution, we present equations which allow for matrix-matching between all measured solutions by fusion of Isotope Dilution and standard addition methods.

  • Blank Correction in Isotope Dilution.
    Analytical chemistry, 2015
    Co-Authors: Enea Pagliano, Zoltan Mester, Juris Meija
    Abstract:

    A novel method for compensation of the procedural blank in Isotope Dilution is presented. This method, entitled “blank-matching”, copes with the blank through experimental design. Both sample and calibration solutions are exposed to the same amount of isotopic standard and same procedural blank. The identical treatment of sample and calibrators eliminates the need for subtracting the procedural blank from the result obtained by Isotope Dilution. A further advantage of the method is that quantitation of the analyte in the procedural blank is not required. Blank-matching is simple and fast to implement, and it permits direct determination of results without further corrections. This aspect has an important metrological outcome: blank-matching Isotope Dilution can be considered a primary method of analysis that does not involve the procedural blank as a potential source of bias.

  • Calibration graphs in Isotope Dilution mass spectrometry.
    Analytica chimica acta, 2015
    Co-Authors: Enea Pagliano, Zoltan Mester, Juris Meija
    Abstract:

    Isotope-based quantitation is routinely employed in chemical measurements. Whereas most analysts seek for methods with linear theoretical response functions, a unique feature that distinguishes Isotope Dilution from many other analytical methods is the inherent possibility for a nonlinear theoretical response curve. Most implementations of Isotope Dilution calibration today either eliminate the nonlinearity by employing internal standards with markedly different molecular weight or they employ empirical polynomial fits. Here we show that the exact curvature of any Isotope Dilution curve can be obtained from three-parameter rational function, y = f(q) = (a0 + a1q)/(1 + a2q), known as the Pade[1,1] approximant. The use of this function allows eliminating an unnecessary source of error in Isotope Dilution analysis when faced with nonlinear calibration curves. In addition, fitting with Pade model can be done using linear least squares.

  • Solution to the Isotope Dilution challenge.
    Analytical and bioanalytical chemistry, 2015
    Co-Authors: Enea Pagliano
    Abstract:

    Over the years, Isotope Dilution mass spectrometry (IDMS) has witnessed many reformulations. One of the earliest expressions for this quantitation model was given by the single Isotope Dilution (IDMS). In IDMS, the mass fraction of an analyte A is obtained from mass spectrometric analysis of a mixture (blend) of sample and an isotopically-enriched form of the analyte (B) which acts as an internal standard: