Quadrupole ICP-MS Research Articles

Human biomonitoring for Cd, Hg and Pb in blood of inhabitants of the Sacco Valley (Italy).

The Sacco Valley (Lazio, Italy) is characterized by high density population and several industrial chemical productions that during the time had led to a substantial amount of by-products. The result was a severe environmental pollution of the area and in particular of the river Sacco. In 1991, the analysis of water and soils samples of three industrial landfills revealed the presence of organochlorine compounds and heavy metals. A research project named "Health of residents living in Sacco Valley area", coordinated by the regional Department of Epidemiology, was undertaken and financed to evaluate the state of health of the population living near those polluted areas. Cd, Hg and Pb were quantified in 246 blood samples of potentially exposed residents of the Sacco Valley by quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS). Individuals who agreed to be sampled did not exhibit high levels of the elements. The distance from the river does not seem to be directly connected with the elements levels in blood. The contribution of these contaminants to the total intake due to ingestion of food was difficult to evaluate. The unclear trend of data would require a characterization of the polluted site with environmental sampling of different matrices.

A method for increasing the precision of isotope ratio analysis on a Quadrupole ICP-MS based on measurements of lead and strontium

In the present article a measurement and data evaluation method for high precision isotope ratio determination with the Quadrupole ICP-MS is presented and applied on Pb and Sr samples. The developed algorithm requires a modification of the measurement procedure. Instead of measuring one well defined concentration, the measurement of a concentration series of the sample has to be performed. The resulting signal intensities of each isotope are plotted against each other in an x,y-diagram. The different concentrations of the samples correlate by a linear model. The slope of the linear line is per definition the isotope ratio. This type of determination is called the Concentration-Gradient-Method, which is abbreviated as CGM. One particularity of this kind of data evaluation is a significant increase of precision and accuracy of the isotope ratio determination performed with Quadrupole ICP-MS. Moreover, a significant intercept is expressed by linear regression. It could be demonstrated that this intercept is a consequence of constant interference overlapping the isotope signal. Constant values that may cause such interference are signal noise and polyatomic interference of the measuring system as well as isobaric interference of the dilution medium. Last is proved in the present work. The potential of the presented method is shown by application examples of liquid and liquid digested Pb and Sr samples. In comparison the Concentration-Gradient-Method (CGM) increases the isotope ratio determination to a factor of approximately 3 and an increase of the accuracy of 10% with respect to the ordinary data acquisition and evaluation procedure.

Isotope ratio determination of objects in the field by portable laser ablation sampling and subsequent multicollector ICPMS

Laser ablation coupled to multicollector inductively coupled plasma mass spectrometry (LA-MC-ICPMS) allows accurate and precise isotope ratio determination of solid samples in a quasi-nondestructive manner, making the technique interesting for isotopic provenance studies of valuable historical artifacts. In order to enable LA-MC-ICPMS analysis of objects that cannot be transported to the laboratory for analysis, a portable laser ablation sampling device was applied. Ablated material was collected on filters, which were subsequently analyzed in the laboratory by means of MC-ICPMS. Filters were analyzed by: (I) acid digestion followed by solution nebulization MC-ICPMS and (II) fast scanning filter ablation coupled to MC-ICPMS. For both procedures, the analytical performance was investigated for lead isotope ratio measurements in ceramics, lead ore (galena) and the metallic lead standard NIST SRM 981. Filter digestion followed by solution analysis allowed determination of lead isotope ratios with external precisions of better than 0.10‰. Mass-dependent deviations towards lighter isotope ratios of 0.10‰ per u were observed for metallic lead, which indicates to a low extent isotopic fractionation during the sampling procedure. Filter ablation coupled to MC-ICPMS resulted in reduced precision compared to the solution measurements. However, it enabled straightforward simultaneous isotopic and elemental analysis by splitting the carrier gas flow to a MC-ICPMS and quadrupole ICPMS. In summary, portable LA sampling followed by MC-ICPMS analysis was shown to enable lead isotope ratio determinations of objects in the field with an analytical performance similar to a laboratory-based analysis. The approach was applied to lead isotope provenancing of ancient Chinese ceramics.

Evaluation of a Collision-Reaction Interface (CRI) for Carbon Effect Correction on Chromium Determination in Environmental Samples by ICP-MS

Spectral interferences in inductively coupled plasma quadrupole mass spectrometry (ICP-MS) may affect several trace element analyses. In this work, the performance of a collision-reaction interface (CRI) for correction of spectral interferences on chromium determination at m/z 52 affected by 40Ar12C+ in a rich-carbon medium was evaluated. Hydrogen or He gases were introduced through sampler or skimmer cones of the CRI for promoting collisions and reactions. Background equivalent concentrations (BEC) and signal-background ratios (SBR) were the chosen parameters for evaluating CRI performance. It was observed that the introduction of both gases through the sampler cone was not effective considering the maximum gas flow rate evaluated at 140 mL min−1. The best condition to reduce polyatomic interferences caused by carbon containing species was obtained while introducing 60 mL min−1 of H2 through the skimmer cone. The trueness of the developed procedure was checked by 52Cr+ determination in certified reference materials. Sequential extractions in acetic acid and ammonium acetate (carbon sources) media, according to the Bureau Communautaire de Référence (BCR) of the Commission of the European Communities, was employed for BCR 701 (Lake Sediment) and microwave-assisted digestion was applied for Sewage Sludge from Industrial Origin (BCR 146 R). The feasibility of the CRI to overcome spectral interferences caused by molecular ions containing carbon on 52Cr+ determined by ICP-MS was demonstrated.

Comparison of PM10 concentrations and metal content in three different sites of the Venice Lagoon: An analysis of possible aerosol sources

The Venice Lagoon is exposed to atmospheric pollutants from industrial activities, thermoelectric power plants, petrochemical plants, incinerator, domestic heating, ship traffic, glass factories and vehicular emissions on the mainland. In 2005, construction began on the mobile dams (MOSE), one dam for each channel connecting the lagoon to the Adriatic Sea as a barrier against high tide. These construction works could represent an additional source of pollutants. PM10 samples were taken on random days between 2007 and 2010 at three different sites: Punta Sabbioni, Chioggia and Malamocco, located near the respective dam construction worksites. Chemical analyses of V, Cr, Fe, Co, Ni, Cu, Zn, As, Mo, Cd, Sb, Tl and Pb in PM10 samples were performed by Inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS) and results were used to identify the main aerosol sources. The correlation of measured data with meteorology, and source apportionment, failed to highlight a contribution specifically associated to the emissions of the MOSE construction works. The comparison of the measurements at the three sites showed a substantial homogeneity of metal concentrations in the area. Source apportionment with principal component analysis (PCA) and positive matrix factorization (PMF) showed that a four principal factors model could describe the sources of metals in PM10. Three of them were assigned to specific sources in the area and one was characterised as a source of mixed origin (anthropogenic and crustal). A specific anthropogenic source of PM10 rich in Ni and Cr, active at the Chioggia site, was also identified.

Human exposure to lead, cadmium and mercury through fish and seafood product consumption in Italy: a pilot evaluation

The presence of selected toxic heavy metals, such as cadmium (Cd), lead (Pb) and mercury (Hg), was investigated in fish and seafood products, namely, blue mussel, carpet shell clam, European squid, veined squid, deep-water rose shrimp, red mullet, European seabass, gilthead seabream, Atlantic cod, European hake, Atlantic bluefin tuna and swordfish so as to assess their human exposure through diet. Metals were detected by quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS) and hydride generation atomic absorption spectrometry (Hg-AAS). Measurements of Cd, Pb and Hg were performed by means of analytical methods validated in compliance with UNI CEI EN ISO/IEC 17025 [2005. General requirements for the competence of testing and calibration laboratories. Milano (Italy): UNI Ente Nazionale Italiano di Unificazione]. The exposure assessment was undertaken matching the levels of Cd, Pb and total Hg with consumption data related to fish and seafood products selected for this purpose. In order to establish human health implications, the estimated weekly intakes (EWIs) for Cd, Pb and Hg were compared with the standard tolerable weekly intakes (TWI) for Cd and provisional tolerable weekly intakes (PTWIs) for Pb and Hg stipulated by the European Food Safety Authority (EFSA) and the Food and Agriculture Organization/World Health Organization (FAO/WHO) Joint Expert Committee on Food Additives (JECFA). The found metal concentrations were largely below the maximum levels (MLs) established at the European Union level with the exception of Cd. This metal exceeded the MLs in squid, red mullet, European hake and Atlantic cod. Squid and blue mussel showed the highest Pb concentrations which accounted for 60% and 10% of the MLs, respectively. Highest Hg levels were found in predatory fish. The concentrations of Hg in swordfish, Atlantic bluefin tuna and red mullet accounted for 50%, 30% and 30% of the MLs, respectively. The EWIs for Cd, Pb and Hg related to the consumption of fish and seafood products by the median of the Italian total population accounted for 20%, 1.5% and 10% of the standard TWI for Cd as well as PTWIs for Pb and Hg, respectively. Furthermore, the EWIs estimated using consumption data concerning Italian consumers did not exceed the standard TWI and PTWIs, except for Cd at 95th percentile.

Measurement of the isotopic abundance of boron-10 by inductively coupled plasma-quadrupole mass spectrometry

This article describes the method for measuring the isotopic abundance of 10B in nuclear grade boron carbide using inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS). The results of investigation revealed that both the integration time and the dwell time have a major influence on the reproducibility of ICP-QMS measurements. As a result of optimization of the measurement conditions, reproducibility below 0.2% relative standard deviation (RSD) (0.17% RSD maximum) was achieved. In addition, the measured value of the isotopic abundance of 10B for each sample well agreed with the values measured by the TIMS. Thus, the method described in the present investigation was very effective in the analysis of isotopic abundance of 10B in B4C or H3BO3. The results of this study suggest that ICP-QMS could be applied to the precise analysis of the isotopic abundance of 10B required in the field of nuclear applications.

Assessment of Polyatomic Interferences Elimination Using a Collision Reaction Interface (CRI) for Inorganic Analysis of Fuel Ethanol by ICP-QMS

The effectiveness of a collision-reaction interface (CRI) as instrumental device and the addition of oxygen in the composition of auxiliary gas were evaluated to minimize polyatomic species generated in plasma gas caused by direct introduction of fuel ethanol samples through spray chambers in inductively coupled plasma quadrupole mass spectrometry (ICP-QMS). The oxygen flow-rate was optimized as a compromise among signal counts, signal to background ratio (SBR), and background equivalent concentration (BEC). For 12.5 mL min−1 O2, ethanol samples diluted 20 times were introduced into the plasma and deposits of carbon compounds on the sampler and/or skimmer cones were not observed. The performance of CRI using H2 and He inserted through the sampler or skimmer cones was evaluated. Hydrogen gas added through the skimmer cone was more efficient to reduce blank and BEC values. This strategy was necessary to eliminate spectral interferences caused by 40Ar12C+, 40Ar16O+, 12C16O+, at isotopes 52Cr+, 56Fe+, 28Si+ and 24Mg+, respectively. Using matrix-matching calibration and Y internal standard, the optimized method was applied to the determination of Al, Ba, Co, Cr, Cu, Fe, Mg, Mn, Mo, Na, Ni, Pb, Sb, Si, V, and Zn in fuel ethanol. Accuracy of developed method was checked after addition/recovery tests. Recoveries and RSD (n = 12) for all elements varied within the 78–114% and 0.4–2% ranges, respectively. Limits of detection for all elements obtained by combining CRI and ICP-QMS were always better than 0.80 µg L−1 except for Si at 14 µg L−1.

Analysis of twenty five impurities in uranium matrix by ICP-MS with iron measurement optimized by using reaction collision cell, cold plasma or medium resolution

An analytical procedure was developed to determine the concentration of 25 impurities (Li, Be, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Mo, Ag, Cd, In, Sm, Eu, Gd, Dy, W, Pb, Bi and Th) in a uranium matrix using the quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS). The dissolution of U3O8 powder was made with a mixture of hydrochloric acid and nitric acid. Then, a selective separation of uranium using the UTEVA column was used before measurement by Q-ICP-MS. The procedure developed was verified using the Certified Reference Material “Morille”. The analytical results agree well except for 5 elements where values are underestimated (Li, Be, In, Pb and Bi). Among the list of impurities, iron was particularly investigated because it is well known that this element possesses a polyatomic interference that increases the detection limit. A comparison between iron detection limits obtained with different methods was performed. Iron polyatomic interference was at least reduced, or at best entirely resolved in some cases, by using the cold plasma or the collision/reaction cell with several gases (He, NH3 and CH4). High-resolution ICP-MS was used to compare the results obtained. A detection limit as low as 8ngL−1 was achieved.

French children's exposure to metals via ingestion of indoor dust, outdoor playground dust and soil: Contamination data

In addition to dietary exposure, children are exposed to metals via ingestion of soils and indoor dust, contaminated by natural or anthropogenic outdoor and indoor sources. The objective of this nationwide study was to assess metal contamination of soils and dust which young French children are exposed to. A sample of 484 children (6months to 6years) was constituted in order to obtain representative results for young French children. In each home indoor settled dust was sampled by a wipe in up to five rooms. Outdoor playgrounds were sampled with a soil sample ring (n=315) or with a wipe in case of hard surfaces (n=53). As, Cd, Cr, Cu, Mn, Pb, Sb, Sr, and V were measured because of their potential health concern due to soil and dust ingestion. The samples were digested with hydrochloric acid, and afterwards aqua regia in order to determine both leachable and total metal concentrations and loadings by mass spectrometry with a quadrupole ICP-MS. In indoor settled dust most (total) loadings were below the Limit of Quantification (LOQ), except for Pb and Sr, whose median loadings were respectively 9 and 10μg/m². The 95th percentile of loadings were 2μg/m² for As, <0.8 for Cd, 18 for Cr, 49 for Cu, <64 for Mn, 63 for Pb, 2 for Sb, 56 for Sr, and <8 for V. Median/95th percentile of loadings in settled dust on outdoor playgrounds were 2/16, <0.8/1.3, 17/53, 49/330, 99/424, 32/393, 2/13, 86/661 and 10/37μg/m² for As, Cd, Cr, Cu, Mn, Pb, Sb, Sr, and V respectively. In outdoor playground soil median/95th percentile of concentrations (μg/g) were 8/26, <0.65/1, 25/52, <26/53,391/956, 27/254, 0.7/4, 54/295, 23/57 for As, Cd, Cr, Cu, Mn, Pb, Sb, Sr, and V respectively. These results are comparable with those observed in other countries. Because of their representative nature, we can assess children's exposures to these metals via soil and dust and the associated risks in urban and rural environments. Ratios of leachable/total concentrations and loadings, calculated on >LOQ measurements, differed among metals. To a lesser extent, they were also affected by type of matrix, with (except for Cd) a greater leachability of dust (especially indoor) compared to soils.

Improvement of the determination of element concentrations in quartz-hosted fluid inclusions by LA-ICP-MS and Pitzer thermodynamic modeling of ice melting temperature

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has become an essential analytical tool for the study of paleofluid chemistry through the analysis of individual fluid inclusions. The calculation of major and trace element concentrations in fluid inclusions is usually based on empirical equations whose significance and accuracy are questionable. In addition, methods for estimation of analytical uncertainties element concentration in individual fluid inclusions are lacking. This study describes a method based upon Pitzer’s thermodynamic model for the calculation of major element (Na, K, Mg and Ca) concentrations in low-to moderate-salinity fluid inclusions. A signal processing protocol, used in combination with the new method is also developed to calculate the concentration, for each inclusion, and uncertainty for each major and trace element. In order to validate the proposed method, synthetic and natural fluid inclusions (from Alpine quartz veins) were ablated with a 193nm ArF excimer laser and analyzed with a quadrupole ICP-MS, equipped with an octopole collision–reaction cell. The difference between the calculated and actual element concentration (i.e. accuracy) does not exceed 20% and the calculated relative standard deviation (i.e. precision) for all element concentrations is ∼10% in standards (glasses, solutions in capillary tubes and synthetic fluid inclusions). The element concentrations obtained with this new method for the Alpine fluid inclusions are in good agreement with those previously measured using Laser Induced Breakdown Spectroscopy (LIBS) or crush-leach methods. Finally, the calculated concentrations and associated uncertainties determined for each element in individual fluid inclusions show that the sensitivity of LA-ICP-MS analysis is high enough to reflect small variations of major and trace element concentrations in the Alpine paleofluid, initially considered to have a constant chemistry. The new approach presented in this paper highlights small but significant variations in the paleofluid chemistry that were not previously detected with conventional LA-ICP-MS data processing.

Solid Phase Extraction Using a Sulfoxide Adsorbent for Preconcentration and Separation of Hg(II) in Natural Water Followed by ICP-MS Measurements

A separation and preconcentration method based on solid-phase extraction using sulfoxide adsorbent was developed for the determination of Hg(II) in natural water samples by inductively coupled plasma mass spectrometry (ICP-MS). The sulfoxide adsorbent was packed into a commercially available syringe-driven column (with a bed volume of 1.0 mL), which permitted off-line sample loading and on-line elution/measurement. The optimized operating conditions were as follows: sample condition for Hg(II) adsorption, 0.5% HCl; sample-loading flow rate, 10 mL min(-1); eluent for recovering Hg(II), 1% cysteine water solution. A test using multi-element mixed solution showed that most trace elements in natural water, except for Bi, could be completely separated from Hg(II). The recoveries of Hg(II) were 99.0 ± 3.2 and 100.7 ± 4.3%, respectively, when 0.64 and 0.16 ng mL(-1) of Hg(II) were added into the test sample. The detection limit of Hg(II) using a quadrupole ICP-MS after 10-fold preconcentration was 1.5 pg mL(-1). The blank value was 2.8 ± 0.5 pg mL(-1).

Reconstructing historical Pb and Hg pollution in NW Spain using multiple cores from the Chao de Lamoso bog (Xistral Mountains)

We have applied a single-bog multi-core approach to reconstruct historical Pb and Hg accumulation in an ombrotrophic bog from NW Spain, Chao de Lamoso (Xistral Mountains). Mercury was determined using a LECO-ALTEC AMA-254 analyzer, Pb with an EMMA-XRF analyzer and stable lead isotopes (four cores) by Quadrupole ICP-MS. Maximum concentrations were 74–122μgg−1 for Pb and 142–300ngg−1 for Hg. Higher variability was found for Hg than for Pb (2–3 times and 1.5 times, respectively). The slopes of the relationship between Hg and Pb cumulative inventories also suggested differences in relative accumulation of both elements. This substantial spatial variability indicates that, compared with Pb, a more extended sampling may be needed for an accurate estimation of Hg accumulation in mires.The isotopic records showed higher and almost constant 206Pb/207Pb ratios (average 1.174±0.004) in the lower sections and a continuous decrease to the surface (minimum 1.141). By using the change in the isotopic composition of Pb we estimated a chronology for the last ∼200years which enabled and approximation of the temporal trends in metal pollution. Based on the average isotopic composition of the studied cores and the application of a simple binary mixing model, six periods with increasing proportions of pollution Pb were identified: prior to ∼1875 AD, with an average proportion lower than 16%; ∼1875–1910 AD, increasing up to 24%; ∼1910–1950 AD, up to 35%; ∼1950–1970, up to 54%; ∼1970–1980 AD, up to 74%; and after ∼1980 AD, increasing up to 80%. The period with the highest rate of increase in recent (since ∼1900 AD) pollution Pb (equivalent to 2% year−1) seems to have started at the maximum in Pb accumulation around the early 1970s. The Hg records showed a more simple evolution with four main phases: prior to ∼1875 AD with enrichments around 1.5-fold the background, ∼1875–1955 AD with increasing enrichments; from ∼1955 AD to ∼1980 AD with maximum values (up to 4.2-fold); and from ∼1980 AD to present, with a steady decline to 2.4-fold.For the most recent period (after ∼1980 AD), the combination of decreasing Pb and Hg concentrations and accumulation rates/enrichments, and low 206Pb/207Pb ratios, may point to a higher relative importance of local sources (i.e. coal burning in a nearby power plant) in atmospheric metal pollution in the area.

An Intercomparison Study of Analytical Methods for the Determination of Magnesium in Low Alloy Steel

AbstractIn an intercomparison study three low alloy steel materials were analyzed on their content of the trace element Mg, and five different analytical techniques were used, namely spark‐OES, inductively coupled plasma optical emission spectrometry (ICP‐OES), inductively coupled plasma time of flight mass spectrometry (ICP‐TOFMS), inductively coupled plasma quadrupole mass spectrometry (ICP‐QMS), and glow discharge mass spectrometry (GD‐MS). Solid steel discs were used for analysis with spark‐OES and GD‐MS. For the analyses with ICP‐OES, ICP‐TOFMS, and ICP‐QMS steel chips were wet‐digested in aqua regia, and the wet‐digestion was performed either in polypropylene tubes placed in a heating block or in Teflon pressure vessels using a microwave assisted system. The Mg concentrations obtained for the three steel materials were: 2.0, 2.8, and 10.3 µg g−1, respectively, and the spread in results was acceptable, giving RSD values in the range of 20–30%.

Dispersive liquid–liquid micro-extraction for simultaneous preconcentration of 14 lanthanides at parts per trillion levels from groundwater and determination using a micro-flow nebulizer in inductively coupled plasma-quadrupole mass spectrometry

This paper reports on the simultaneous extraction and preconcentration of 14 lanthanide (rare earth) elements in groundwater by a dispersive liquid–liquid microextraction (DLLME) method and their determination by inductively coupled plasma quadrupole mass spectrometry (ICP-QMS). A low flow rate (200 μL min−1) SeaSpray™ micro-flow nebulizer was used for the sample introduction. In this method, the rare earth elements are complexed with 2,6-pyridinedicarboxylic acid (2,6-PDCA) in the presence of Aliquat® 336 (tricaprylmethylammonium chloride), which enhanced the hydrophobicity of the ion-association complex, resulting in its improved extraction into chloroform. The extraction was carried out after adjusting the pH of the water sample to 4. The rare earth ions were back extracted from the chloroform layer with nitric acid for determination by ICP-QMS. Some effective parameters for complex formation and extraction, such as volume of extractant/disperser solvent, extraction time, pH and concentration of the chelating agent and surfactant, have been optimized. Under optimum conditions, an average preconcentration factor of 97 was obtained for 50 mL of water sample for determination by ICP-QMS. The calibration graphs were linear in the range of 1–100 ng L−1 for the 14 REEs, with limits of detection ranging from 0.05–0.55 ng L−1. The precision ranged from 1–5% R.S.D. (n = 3), when processing 50 mL aliquots of groundwater. The method has been applied to a few groundwater samples. The recoveries obtained for the rare earth elements in groundwater samples spiked to 10 ng L−1 were 92–109%.

Interference standard and oxide ion detection as strategies to determine phosphorus and sulfur in fuel samples by inductively coupled plasma quadrupole mass spectrometry

Due to their high ionization energies and severe spectral interferences, P and S are challenging elements in inductively coupled plasma quadrupole mass spectrometry (ICP-QMS). An alternative to improve sensitivity is to monitor P and S oxide and hydroxide species which are easily formed under cool plasma conditions. To improve accuracy, an interesting approach is the interference standard (IFS) method. Similar to internal standardization, the IFS method is based on the idea that interfering polyatomic ions and some Ar species (IFS) present similar behaviors in the plasma. Thus, by applying a conventional external calibration method and using the analytical–IFS signal ratio, one can minimize the contribution of the interfering ion to the analytical signal and improve accuracy. In this work, plasma operating conditions are adjusted to maximize the formation of 31P16O+, 32S16O+ and 32S16OH+. Under the optimal conditions and using the 36ArH+ as an IFS probe, limits of detection as low as 5 and 600 μg l−1 are obtained for P and S determined at m/z 47 and 49, respectively. The efficiency of the IFS method in reducing interferences, e.g.30Si16OH+ on 31P16O+, and 31P16OH+ on 32S16O+, is also evaluated. Accuracy is significantly improved in lubricating oil, diesel and biodiesel analyses. No significant differences are observed between the reference values and the ones obtained with the 36ArH+ IFS probe at a 95% confidence level. The 36Ar+ and 38Ar+ IFS probes are also efficient in most determinations.

Trace elements in human follicular fluid: development of a sensitive multielement ICP-MS method for use in biomonitoring studies

Little information is available in the literature regarding trace element analysis of human follicular fluid. Most peer-reviewed publications offer few details about sample preparation, method development, or method validation. We have attempted to fill this gap in current knowledge by providing comprehensive details of our method development and validation process for the measurement of 24 trace elements (As, Ba, Be, Cd, Co, Cr, Cs, Cu, Hg, Mo, Mg, Mn, Pb, Pt, Rb, Se, Sb, Sn, Sr, Tl, U, V, W, Zn) in follicular fluid. A number of different sample preparation procedures were explored, with a goal of optimizing method detection limits (MDLs), for both quadrupole-inductively coupled plasma-mass spectrometry (Q-ICP-MS) and sector field (SF)-ICP-MS. Human follicular fluid samples (n = 72) were obtained from 64 women undergoing in vitro fertilization (IVF) treatment, and were successfully analyzed for 24 trace elements using SF-ICP-MS.

U-series dating of carbonates using inductively coupled plasma-quadrupole mass spectrometry

We describe an analytical methodology to quantify 238U– 234U and 230Th using isotope-dilution systematics and inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS) for geochronological purposes. This required characterization of the mass spectrometer detector performance over a large dynamic range, including a careful calibration between pulse and analogue ion-counting modes. Our methodology gives an analytical precision for 234U/ 238U and 230Th/ 238U of 4‰ and 7‰ (2 × standard error), respectively, and yields 230Th-ages with 4–5% uncertainty from 500 ng of 238U. We tested our methodology by analyzing carbonate samples (corals and speleothems) which were previously dated using MC-ICPMS; excellent agreement between both techniques was obtained. Our results indicate that ICP-QMS is suitable to obtain valuable meaningful geochronological data, but it is limited to dating samples older than 1 ka, and younger than 400 ka. Our methodology thus represents an attractive alternative to obtain geochonological data to select the most interesting samples prior to high-precision analysis. Moreover, such data would also valuable to build preliminary age-models, which can be further complemented with high-precision analyses.

Application of the interference standard method for the determination of sulfur, manganese and iron in foods by inductively coupled plasma mass spectrometry

The interference standard method (IFS) is evaluated to improve the accuracy of the determination of S, Mn and Fe in meat and grain samples by inductively coupled plasma quadrupole mass spectrometry (ICP-QMS). Due to ICP-QMS relatively low resolution, polyatomic interferences caused by 16O 2 +, ( 16OH) 2 +, 40Ar 14NH +, and 40Ar 16O +, for example, can compromise determinations at m/ z 32, 34, 55, and 56, respectively. In IFS, differently from traditional internal standard methods, plasma naturally occurring species are used to correct for variations in the interference signal rather than the analyte signal. The method is based on the hypothesis that the interfering ion and the IFS probe present similar behaviors in the plasma, and that by using the analytical (analyte plus interference)/IFS signal ratio one could reduce variations due to interference and, consequently, improve accuracy. In this work, this strategy is evaluated in real sample applications and significant improvements on accuracy are observed for 32S, 34S, 55Mn, and 56Fe determinations. Recoveries ranging from 72% for Mn to 105% for Fe in two different standard reference materials are obtained using the 38Ar probe. These analytes are successfully determined in meat and grain samples with concentrations ranging from 4.42 μg g −1 for Mn in corn to 7270 μg g −1 for S in chicken liver. The method is compared with other strategies such as internal standardization and mathematical correction. No instrumental modification or introduction of foreign gases is required, which is especially attractive for routine applications.

Identification of sources of lead exposure in French children by lead isotope analysis: a cross-sectional study

BackgroundThe amount of lead in the environment has decreased significantly in recent years, and so did exposure. However, there is no known safe exposure level and, therefore, the exposure of children to lead, although low, remains a major public health issue. With the lower levels of exposure, it is becoming more difficult to identify lead sources and new approaches may be required for preventive action. This study assessed the usefulness of lead isotope ratios for identifying sources of lead using data from a nationwide sample of French children aged from six months to six years with blood lead levels ≥25 μg/L.MethodsBlood samples were taken from 125 children, representing about 600,000 French children; environmental samples were taken from their homes and personal information was collected. Lead isotope ratios were determined using quadrupole ICP-MS (inductively coupled plasma - mass spectrometry) and the isotopic signatures of potential sources of exposure were matched with those of blood in order to identify the most likely sources.ResultsIn addition to the interpretation of lead concentrations, lead isotope ratios were potentially of use for 57% of children aged from six months to six years with blood lead level ≥ 25 μg/L (7% of overall children in France, about 332,000 children), with at least one potential source of lead and sufficiently well discriminated lead isotope ratios. Lead isotope ratios revealed a single suspected source of exposure for 32% of the subjects and were able to eliminate at least one unlikely source of exposure for 30% of the children.ConclusionsIn France, lead isotope ratios could provide valuable additional information in about a third of routine environmental investigations.