Noise identification and sampling frequency determination for precise Pb isotopic measurements by quadrupole-based Inductively Coupled Plasma Mass Spectrometry

Abstract

Abstract. Analytical precision of the isotope ratios measured by quadrupole-based ICP-MS is drastically controlled by the lowfrequency noises which originate from nebulisation and vaporisation processes, and from sample introduction systems. The undesirable influence of these latter can be however reduced by choosing efficiently the operating parameters. In the present study, the choice of the stabilisation time necessary in peak jump mode, and the one of the number of sweeps are discussed in the light of noise power spectra obtained with various speeds of the peristaltic pump used as sample introduction system. Obviously, the settings proposed are probably efficient only on our own ICP-MS, but they can be determined without any difficulty on any other equipment, only by following the methodology detailed here. With such guidelines, experimental within-run RSD % were observed following closely those predicted by the counting statistics (∼ 110 %). The isotopic measurements of natural samples (overbank sediments, airborne particulate matter, lichens and rainwater) exhibited fair accuracy and good reproducibility, making highly convenient the use of the ICP-MS, at least in an environmental purpose.Keywords. Inductively coupled plasma mass spectrometry -lead isotope ratios -instrumental parameters -optimisationnoise -quality control.

Historical mining and smelting in the Vosges Mountains (France) recorded in two ombrotrophic peat bogs

“…Uncertainties of ± 15% were therefore considered for all elements measured by ICP-MS. Lead from the remaining two-thirds aliquot was pre-concentrated on ionic resin AG1X4 (Biorad) and measured for isotopic abundance by Q-ICP-MS. Details regarding lead separation, instrumental settings, mass bias correction by bracketing, and dead time correction can be found elsewhere (Monna et al, 1998(Monna et al, , 2000. The BCR-1, a certified reference material processed together with peat samples, yielded lead isotopic compositions ( 206 Pb/ 207 Pb = 1.205 ± 0.004 and 208 Pb/ 206 Pb = 2.053 ± 0.006, at 95% confidence level) in good agreement with values reported in the literature ( 206 Pb/ 207 Pb = 1.2036 and 208 Pb/ 206 Pb = 2.0582; Baker et al, 2004).…”

Lichens Used as Monitors of Atmospheric Pollution Around Agadir (Southwestern Morocco)—A Case Study Predating Lead-Free Gasoline

“…Lead isotopic compositions (i.e., 206 Pb/ 207 Pb and 208 Pb/ 207 Pb) were determined using a quadrupole-based ICP-MS Perkin Elmer Elan 6000 (University of Reading, UK) or an HR-ICP-MS Thermo Element 2 (University of Paris Diderot, France). More details about acquisition settings and mass bias corrections by bracketing a NIST SRM 981 (common lead isotopic standard) solution can be found in Monna et al (1998Monna et al ( , 2000. Duplicates exhibit reproducibility within the limits of instrumental error, which are typically of 2 and 6 at the third decimal place (95% confidence level) for the 206 Pb/ 207 Pb and 208 Pb/ 207 Pb ratios, respectively (Tables 1 and 3).…”

Environmental impact of early palaeometallurgy: pollen and geochemical analysis

“…An aliquot of the solution was measured by an HP 4500 inductively coupled plasma -mass spectrometer (ICP-MS) to determine Cu, Zn, Cd, and Pb concentrations. Lead from another aliquot was purified using the conventional ionic resin AG1X4 (Biorad) and measured for its isotopic composition by a quadrupole-based HP 4500 (see Monna et al 1998Monna et al , 2000 for more details about the chemical procedure and precision). Blanks and reference material standards, including NIST 1547, JSD 1, JSD 2, NIST 1547, PACS-1 and BCSS-1, were also systematically added to each set of unknown samples in order to check accuracy and precision Table 1.…”