Evaluation of detector dead time calculation models for ICP-MS

Nelms, Simon M.; Quétel, Christophe R.; Prohaska, Thomas; Vogl, Jochen; Taylor, Philip

doi:10.1039/b007913h

Cited by 168 publications

(129 citation statements)

References 17 publications

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“…Solutions of the Pb isotope standard NIST-981 (typically 8, 16, 24, 32 and 40 µg L -1 ) were used to determine correction factors for the detector 'dead time' and for mass bias (K-factors) during analysis. [25] Only data measured in true pulse-counting mode were used to determine isotopic abundances; data were rejected if the detector 'tripped' to an analogue signal.…”

Section: Measurement Of Pb Isotopic Abundancementioning

confidence: 99%

Fractionation of lead in soil by isotopic dilution and sequential extraction

et al. 2011

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The chemical reactivity of lead in soil is difficult to assess and depends on both soil conditions and the origins of the lead. This paper tests the combined application of lead isotopic techniques and chemical extraction to our understanding of lead fractionation in soils. Possibly against expectation, it appears that the 'reactivity' of lead can be high and yet there is tentative evidence that the original source of the metal affects its fractionation in soil, even after long contact times. Abstract 'Reactivity' or 'lability' of lead is difficult to measure using traditional methods. We investigated the use of isotopic dilution with 204 Pb to determine metal reactivity in four soils historically contaminated with contrasting sources of Pb, including (i) petrol-derived Pb, (ii) Pb/Zn mine-spoil, (iii) long-term sewage sludge application and (iv) C19 th urban waste disposal; total soil Pb concentrations ranged from 217 -13600 mg kg -1 . A post-spike equilibration period of three days and 5.0 x 10 -4 M EDTA electrolyte provided reasonably robust conditions for measuring isotopically-exchangeable Pb although in acidic organic soils a dilute Ca(NO 3 ) 2 electrolyte may be better to avoid mobilisation of 'non-labile' Pb. Results showed that the reactive pool of soil Pb is often larger than may be intuitively expected but varies with the original Pb source. A comparison of isotopic exchangeability with the results of a sequential extraction procedure showed that (isotopically) 'non-labile' Pb may be broadly equated with 'residual' Pb in organic soils. However, in mineral soils the 'calcareous' and 'oxide-bound' Pb fractions included non-labile forms of Pb. De-coupling the isotopic signature of labile and nonlabile Pb pools suggested that, despite prolonged contact with soil, differences between the lability of the original contaminant and the native soil Pb may remain.

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Section: Measurement Of Pb Isotopic Abundancementioning

confidence: 99%

Fractionation of lead in soil by isotopic dilution and sequential extraction

et al. 2011

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“…50-1142, CPI International, Amsterdam, The Netherlands) for the Element2, and with a forced low-flow concentric glass nebulizer (P/N 1110720, MicroMist, Glass Expansion, West Melbourne, Australia) for the Elan 6000. All the measurements were carried out in the pulse counting mode, and the dead time effects [14] were corrected following specific methods described elsewhere [15] (using Method 2 for the Element2 and Method 4 for the Elan 6000). Dead time values of 14 Ϯ 4 ns (k ϭ 2) and 57 Ϯ 10 ns (k ϭ 2) were found for the Element2 and the Elan 6000, respectively.…”

Section: Instrumentationmentioning

confidence: 99%

Low uncertainty reverse isotope dilution ICP-MS applied to certifying an isotopically enriched Cd candidate reference material: A case study

Trešl

Quétel

2005

J. Am. Soc. Mass Spectrom.

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An analytical method is presented based on reverse isotope dilution single detector inductively coupled plasma magnetic sector mass spectrometry (ID-ICP-SMS) and applied to the specific case of the certification of a 111 Cd enriched candidate Cd spike calibration material (nominal mass fraction 10 mg kg Ϫ1 in 5% HNO 3 solution). Uncertainty propagation was used as a tool for both determining the analytical approach and validating it. The robustness of close to "exact matching" reverse IDMS to correction of measured isotope intensities for multiplicative (mass discrimination) and (semi)additive effects (dead time, instrumental background, and isobaric interference) is discussed. The very low experimental relative standard deviation of the mean (0.08%) of eight replicate determinations indicated that all significant sources of uncertainty had probably been taken into account for the estimation of the final combined uncertainty statement (U c ϭ 0.17%, k ϭ 1). IRMM-621 was used as comparator. Uncertainties on IUPAC isotopic abundances of 111 Cd and 112 Cd, for the natural Cd solution involved between the two enriched materials, formed nearly 60% of U c . The repeatability of the isotope ratio measurements contributed less than 10%. Correction for procedural blank necessitated somewhat unusual calculations (potential contamination of an enriched material with natural Cd). The procedure also involved a quadrupole based ICP-MS judged to be appropriate for the characterization of the isotopic composition. For comparison purposes, direct IDMS results are simulated using identical experimental input data. Finally, a significant background signal in the 106 -116 mass region, observed only with the magnetic sector instrument, was attributed to argon based isobaric interferences. I sotope dilution mass spectrometry (IDMS) was recognized as having the potential to be a primary ratio method of measurement [1]. When applied correctly, it can be of "practical use in establishing traceability to the SI unit system" [2] and accurate results with sufficiently small uncertainties can be achieved. The advantages and disadvantages of the IDMS method have been discussed [3,4] since its invention nearly 50 years ago. One of the significant advantages over other approaches is that the analyte recovery does not have to be quantitative, providing that isotopic equilibration has been achieved between all of the analyte and added spike material. Commonly there is the reverse IDMS (or two-way IDMS) whereby the spike material is calibrated against a well-characterized assay material. The alternative is direct IDMS (or one-way IDMS) which is faster but requires a spike material already reliably certified "once for all" for the element content and isotopic composition. Direct IDMS has the potential to lead to relative combined uncertainties on the amount content determination of ϳ1% (k ϭ 2) even with quadrupole ICP-MS (inductively coupled plasma mass spectrometry) instrumentation [5]. In many cases this is entirely fit for the purpose and a bett...

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“…Although there are various approaches for experimental determination of the dead time, 175 they are all based on the fact that appropriate correction of the measured signal intensities for dead time losses should result in a sensitivity (signal intensity/concentration unit) independent of the signal intensity and hence, independent of analyte concentration.…”

Section: Detector Issuesmentioning

confidence: 99%

Inductively coupled plasma- and glow discharge plasma-sector field mass spectrometry : Part I. Tutorial: Fundamentals and instrumentation

Jakubowski

Prohaska

Rottmann

et al. 2011

J. Anal. At. Spectrom.

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The aim of this series of two reviews is to introduce the basic concepts of ICP and GD sector field instruments, to discuss their peculiarities and performance, to present selected analytical applications for demonstration of the 'state of the art' and, finally, to identify possible future trends and developments. Part I focuses on fundamentals, instrumentation and operation of instruments to give an overview of the capabilities of the actual commercially available instrumentation, whereas selected applications will be discussed in detail in part II.

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Evaluation of detector dead time calculation models for ICP-MS

Cited by 168 publications

References 17 publications

Fractionation of lead in soil by isotopic dilution and sequential extraction

Fractionation of lead in soil by isotopic dilution and sequential extraction

Low uncertainty reverse isotope dilution ICP-MS applied to certifying an isotopically enriched Cd candidate reference material: A case study

Inductively coupled plasma- and glow discharge plasma-sector field mass spectrometry : Part I. Tutorial: Fundamentals and instrumentation

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