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The effect of isotopic composition on the uncertainty of routine metal mass concentration measurements in ambient air.

Brown RJ, Goddard SL, Brown AS, Yardley RE - J Autom Methods Manag Chem (2009)

Bottom Line: It is observed that the uncertainty contribution from possible variation in the isotopic composition of the sample depends on the element in question, but can be significant (e.g., for Pb, Cd, and Hg).Therefore, in order to confirm the validity of this quantification methodology and its uncertainty budget, the isotopic composition of the calibration standards used for quantification has been determined.The results of this analysis are presented here.

View Article: PubMed Central - PubMed

Affiliation: Analytical Science Team, National Physical Laboratory, Teddington, Middlesex TW11 0LW, UK.

ABSTRACT
The main sources of uncertainty encountered during the analysis of the mass concentration of metals in ambient air as part of the operation of the UK Heavy Metals Monitoring Network are presented. It is observed that the uncertainty contribution from possible variation in the isotopic composition of the sample depends on the element in question, but can be significant (e.g., for Pb, Cd, and Hg). The working curve method for the ICP-MS analysis of metals in solution, with a low resolution, high throughput instrument measuring at one m/z ratio per element, relies on the relative abundance of the isotopes under consideration being the same in both the sample and the calibration solution. Calculation of the uncertainty in this analysis assumes that the isotopic composition variation within the sample and calibration solution is limited to a defined range. Therefore, in order to confirm the validity of this quantification methodology and its uncertainty budget, the isotopic composition of the calibration standards used for quantification has been determined. The results of this analysis are presented here.

No MeSH data available.


The fraction of the overallmeasurement uncertainty for each metal contributed by the uncertainty in δX.
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Related In: Results  -  Collection


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fig2: The fraction of the overallmeasurement uncertainty for each metal contributed by the uncertainty in δX.

Mentions: As can be seen, thecontribution from the possible variation in the isotopic composition of thesample is strongly dependent on the element being determined. This contributionis very significant for Pb, significant for Hg, and Cd, less significant forCu, Zn and Pt, and negligible for Cr, Ni, Fe, and V. This is highlighted in Figure 2 which showsthe fraction of the overall measurement uncertainty contributed by uncertaintyin the isotopic composition of the sample being measured [25]. As expected from the data in Figure 1, thiscontribution is very significant for Pb, notable for Hg, Cd and possibly Cu,and insignificant for all other elements.


The effect of isotopic composition on the uncertainty of routine metal mass concentration measurements in ambient air.

Brown RJ, Goddard SL, Brown AS, Yardley RE - J Autom Methods Manag Chem (2009)

The fraction of the overallmeasurement uncertainty for each metal contributed by the uncertainty in δX.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2637369&req=5

fig2: The fraction of the overallmeasurement uncertainty for each metal contributed by the uncertainty in δX.
Mentions: As can be seen, thecontribution from the possible variation in the isotopic composition of thesample is strongly dependent on the element being determined. This contributionis very significant for Pb, significant for Hg, and Cd, less significant forCu, Zn and Pt, and negligible for Cr, Ni, Fe, and V. This is highlighted in Figure 2 which showsthe fraction of the overall measurement uncertainty contributed by uncertaintyin the isotopic composition of the sample being measured [25]. As expected from the data in Figure 1, thiscontribution is very significant for Pb, notable for Hg, Cd and possibly Cu,and insignificant for all other elements.

Bottom Line: It is observed that the uncertainty contribution from possible variation in the isotopic composition of the sample depends on the element in question, but can be significant (e.g., for Pb, Cd, and Hg).Therefore, in order to confirm the validity of this quantification methodology and its uncertainty budget, the isotopic composition of the calibration standards used for quantification has been determined.The results of this analysis are presented here.

View Article: PubMed Central - PubMed

Affiliation: Analytical Science Team, National Physical Laboratory, Teddington, Middlesex TW11 0LW, UK.

ABSTRACT
The main sources of uncertainty encountered during the analysis of the mass concentration of metals in ambient air as part of the operation of the UK Heavy Metals Monitoring Network are presented. It is observed that the uncertainty contribution from possible variation in the isotopic composition of the sample depends on the element in question, but can be significant (e.g., for Pb, Cd, and Hg). The working curve method for the ICP-MS analysis of metals in solution, with a low resolution, high throughput instrument measuring at one m/z ratio per element, relies on the relative abundance of the isotopes under consideration being the same in both the sample and the calibration solution. Calculation of the uncertainty in this analysis assumes that the isotopic composition variation within the sample and calibration solution is limited to a defined range. Therefore, in order to confirm the validity of this quantification methodology and its uncertainty budget, the isotopic composition of the calibration standards used for quantification has been determined. The results of this analysis are presented here.

No MeSH data available.