Isotope-ratio measurements of lead in NIST standard reference materials by multiple-collector inductively coupled plasma mass spectrometry

The capability of a second-generation Nu Instruments multiple collector inductively coupled plasma mass spectrometer (MC-ICP-MS) has been evaluated for precise and accurate isotope-ratio determinations of lead. Essentially the mass spectrometer is a double-focusing instrument of Nier-Johnson analyzer geometry equipped with a newly designed variable-dispersion ion optical device, enabling the measured ion beams to be focused into a fixed array of Faraday collectors and an ion-counting assembly. NIST SRM Pb 981, 982, and 983 isotopic standards were used. Addition of thallium to the lead standards and subsequent simultaneous measurement of the thallium and lead isotopes enabled correction for mass discrimination, by use of the exponential correction law and 205Tl/203Tl = 2.3875. Six measurements of SRM Pb-982 furnished the results 206Pb/204Pb = 36.7326(68), 207Pb/204Pb = 17.1543(30), 208Pb/204Pb = 36.7249(69), 207Pb/206Pb = 0.46700(1), and 208Pb/206Pb = 0.99979(2); the NIST-certified values were 36.738(37), 17.159(25), 36.744(50), 0.46707(20), and 1.00016(36), respectively. Direct isotope lead analysis in silicates can be performed without any chemical separation. NIST SRM 610 glass was dissolved and introduced into the MC-ICP-MS by means of a micro concentric nebulizer. The ratios observed were in excellent agreement with previously reported data obtained by TIMS and laser ablation MC-ICP-MS, despite the high Ca/Pb concentration ratio (200/1) and the presence of many other elements at levels comparable with that of lead. Approximately 0.2 microg lead are sufficient for isotope analysis with ratio uncertainties between 240 and 530 ppm.     

Accuracy and long-term reproducibility of lead isotopic measurements by multiple-collector inductively coupled plasma mass spectrometry using an external method for correction of mass discrimination

The precision of isotopic measurements of Pb by thermal ionization mass spectrometry (TIMS) is limited by the fact that this element does not possess an invariant isotope ratio that can be used for the correction of mass fractionation by internal normalization. Multiple-collector inductively coupled plasma mass spectrometry (MC-ICPMS) can overcome this limitation, because with plasma ionization, elements with overlapping mass ranges are thought to display identical mass discrimination. With respect to Pb, this can be exploited by the addition of Tl to the sample solutions; the mass discrimination factor obtained for Tl can then be used for the correction of the measured Pb isotope ratios. In this article we present the results of a detailed study that investigates the accuracy and precision of such an external correction technique for mass discrimination based upon the results of multiple analyses of a mixed standard solution of NIST SRM-981 Pb and SRM-997 Tl. Our data indicate that normalization of the Pb isotope ratios to the certified isotopic composition of SRM-997 Tl produces Pb isotopic results that are significantly lower than recently published reference values by TIMS. This systematic offset can be eliminated by renormalization of the Pb data to a different Tl isotopic composition to obtain an empirically determined mass discrimination factor for Pb that generates accurate results. It is furthermore shown that a linear law is least suited for the correction of mass discrimination, whereas a power or exponential law function provide significantly more accurate and precise results. In detail, it appears that a power law may provide the most appropriate correction procedure, because the corrected Pb isotope ratios display less residual correlations with mass discrimination compared to the exponentially corrected data. Using an exponential or power law correction our results, obtained over a period of over seven months, display a precision (2σ) of better than 60 parts per million (ppm) for ²⁰⁸Pb/²⁰⁶Pb and ²⁰⁷Pb/²⁰⁶Pb and of better than 350 ppm for ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb/²⁰⁴Pb, and ²⁰⁸Pb/²⁰⁴Pb. This represents a significant improvement compared to conventional TIMS techniques and demonstrates the potential of MC-ICPMS for routine, high-precision measurements of Pb isotopic compositions.     

Precise isotope-ratio measurements of lead species by capillary gas chromatography hyphenated to hexapole Multicollector ICP–MS

The precision and accuracy of lead isotope-ratio determination on a short transient signal has been assessed by coupling capillary gas chromatography to the Isoprobe (Micromass, UK), a single-focusing inductively coupled plasma mass spectrometer with multicollector detection. A T-piece connecting the GC transfer line to the torch enabled continuous aspiration of thallium solution for mass-bias correction. The volatile lead species PbEt₄ was derivatized from NIST isotopic certified lead standard SRM 981 and different amounts of PbEt₄ dissolved in iso-octane were injected into the GC. Chromatograms were recorded in multicollection mode by use of Faraday cups; seven isotopes (²⁰⁴Pb, ²⁰⁶Pb, ²⁰⁷Pb, ²⁰⁸Pb, ²⁰³Tl, ²⁰⁵Tl, and ²⁰²Hg) were monitored simultaneously at a transient resolution of 160 ms. PbEt₄ peaks were obtained with a half-width of 1.2 s and a base width of 3.5 s. Lead isotope ratios were calculated from the peak areas integrated for each lead isotope, giving precision in the range of 0.02 to 0.07% for ratios of high-abundant isotopes and injections of 5 and 50 pg absolute amount as lead (five replicates). Mass bias was found to be about 0.5% per mass unit and was corrected by using the continuously measured thallium signals at ²⁰³Tl and ²⁰⁵Tl. After mass-bias correction, deviation of the certified lead ratio values was found to be in the range of 0.02 to 0.15% accuracy.     

Isotopic precision for a lead species (PbEt4) using capillary gas chromatography coupled to inductively coupled plasma-multicollector mass spectrometry

Precision and accuracy of lead isotope ratios of a volatile lead species (PbEt₄) were determined by coupling a capillary GC to a magnetic sector multicollector ICP-MS. PbEt₄ was prepared by ethylation of a certified lead isotope solution (NIST SRM 981). Coupling was achieved by a transfer line, which allowed simultaneous introduction of a thallium standard solution to correct for mass discrimination. Seven isotopes (²⁰²Hg, ²⁰³Tl, ²⁰⁴Pb, ²⁰⁵Tl, ²⁰⁶Pb, ²⁰⁷Pb, ²⁰⁸Pb) were monitored simultaneously with a transient resolution of 50 ms. Pb isotope ratios for the PbEt₄ peaks were calculated using transient peak integrals of each isotope signal. Absolute detection limits were 20 (²⁰⁴Pb), 0.7 (²⁰⁶Pb), 1 (²⁰⁷Pb) and 0.3 pg (²⁰⁸Pb). Precision was assessed for five replicate injections of PbEt₄ in iso-octane, corresponding to a total amount of 300 pg of Pb. Precision of isotope ratios for ²⁰⁶Pb, ²⁰⁷Pb and ²⁰⁸Pb were better than 0.07% (RSD), with ratios including ²⁰⁴Pb being one order of magnitude worse. Accuracy using mass bias correction via ²⁰³Tl/²⁰⁵Tl ranged from 0.18% for ²⁰⁸Pb/²⁰⁶Pb to 0.9% for ²⁰⁸Pb/²⁰⁴Pb.     

Precise and accurate determination of lead isotope ratios in mining wastes by ICP-QMS as a tool to identify their source

A methodology for a precise and accurate determination of lead isotope ratios in mining wastes by inductively coupled plasma quadrupole-based mass spectrometry (ICP-QMS) has been developed. The study of instrumental bias factors led to the conclusion that internal correction to compensate mass discrimination is required as well as an interference equation correction when Hg is present. The proposed method has been applied to determine lead isotope ratios in several mining wastes, soils and sediments collected at three mining areas in Spain (Aran Valley, Cartagena and Osor).Statistical analysis highlights that ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁷Pb lead isotope ratios can be used as a fingerprint of mining waste origin which is related to the geological age of the lead ore.On the other hand, no statistically significant isotopic differences between original ore samples (galena) and processing wastes within a mining district were found, corroborating a unique lead source. Moreover, the lead isotopic composition of soil and sediment samples collected at the studied mining areas is close to that determined in the mining tailings from the same areas, suggesting that the unusual high content of lead in these samples is derived from mining activities rather than from other lead sources.     

Determination of sources of lead in tap water by inductively coupled plasma mass spectrometry (ICP-MS)

We measured the concentrations of Pb and its isotope ratios in coconmittantly obtained tap water and plumbing materials by inductively coupled mass spectrometry (ICP-MS). The Pb concentrations were determined by external calibration with²⁰⁹Bi as an internal standard. Isotope ratios were measured and mass discrimination corrected by normalization to NIST SRM-981 (common lead isotopic standard). Student/s t-test was used to compare the isotopic ratios of²⁰⁶Pb/²⁰⁷Pb,²⁰⁶Pb/²⁰⁸Pb, and²⁰⁷Pb/²⁰⁸Pb in the tap water with those in various plumbing materials. The comparisons revealed that the source of Pb in most of the tap water samples was derived from copper pipe or solder.     

Evaluation of extraction/digestion techniques used to determine lead isotopic composition in forest soils

Lead isotopic studies in soils provide an efficient tool for tracing the sources of lead pollution. Five different extraction/digestion techniques (0.05 M EDTA, 0.5 M HNO₃, 2 M HNO₃, aqua regia, total digestion) were used for lead isotopic composition (²⁰⁶Pb/²⁰⁷Pb) determination in three forest soil profiles with different kinds of prevailing Pb contamination (unpolluted area, smelting area and vicinity of a motorway). The results obtained showed that all extraction/digestion methods used for the determination of ²⁰⁶Pb/²⁰⁷Pb ratios in surface horizons containing high organic matter contents gave statistically identical values (according to the Tukey test). In mineral soil horizons, differences between the individual extraction/digestion methods could be observed (the lowest ²⁰⁶Pb/²⁰⁷Pb ratios were obtained from EDTA extracts, corresponding to weakly bound anthropogenic lead, and the highest ²⁰⁶Pb/²⁰⁷Pb ratios were obtained from total digestion). The combination of total digestion and EDTA extraction (labile lead fraction) seems to be the optimal combination for ²⁰⁶Pb/²⁰⁷Pb ratio determination and optimal result interpretation.     

Determination of lead concentrations and isotope ratios in recent snow samples from high alpine sites with a double focusing ICP-MS

A double focusing ICP-MS, equipped with a Micro Concentric Nebulizer, has been used to determine concentrations and isotopic ratios of lead in recent snow samples (1993–1996) from high alpine sites in Switzerland. Concentrations varied between 0.02 ± 0.002 and 5.5 ± 0.15 ng/g and are slightly lower than concentrations reported by Atteia [1], by Batifol et al. [2], and by Wagenbach et al. [3] for precipitation samples from similar remote sites in Europe. Since concentrations of lead in the fresh snow samples were mainly in the lower pg/g range, the method to determine the isotopic ratios ²⁰⁷Pb/²⁰⁶Pb and ²⁰⁸Pb/²⁰⁶Pb had to be optimized. They could finally be determined with an average standard error of 0.14% within 12 min and a total sample consumption of 0.8 mL. The average ratios ²⁰⁷Pb/²⁰⁶Pb and ²⁰⁸Pb/²⁰⁶Pb were 0.875 and 2.117, respectively. These values are comparable to isotopic compositions of lead in aerosols collected in Western Europe [4] and are less radiogenic than predicted by Grousset et al. [5]. Our data indicate that, although lead emissions from traffic have decreased largely during the last 10 years, the contribution from this source in modern snow is still detectable and seems to be equal to the lead input from other anthropogenic sources (e.g. waste incineration, industry).     

电感耦合等离子体质谱法测定黄沙土壤中铅同位素比

用电感耦合等离子体质谱法（ＩＣＰ—ＭＳ）测定了５个黄沙原土样品中铅同位素比２０７Ｐｂ／２０６Ｐｂ、２０８Ｐｂ／２０６Ｐｂ，样品来自被认为是黄沙气溶胶源地区，为了使铅同位素测量中质量偏差和漂移减至最少，在样品中加入了铊标准溶液，测量２０５Ｔｌ／２０３Ｔｌ比，校正质量数差别选择的影响．同时，采用ＩＣＰ—ＭＳ和电感耦合等离子体原子发射光谱法（ＩＣＰ一ＡｌＳ）测定了随粒径变化样品中１２种元素浓度的变化．     

ICP-MS measurements of lead isotopic ratios in soils heavily contaminated by lead smelting: tracing the sources of pollution

The Pb isotopic composition (²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁶Pb) in smelter-impacted soils was measured using a quadrupole-based ICP-MS. Four forest/tilled soil profiles were sampled according to the distance from the lead smelter in Píbram (Czech Republic), prevailing wind direction, geological background and soil type. The results were compared with the Pb isotopic composition of bedrocks and waste materials from Pb metallurgy (smelting slags, air-pollution-control residues). The isotopic composition of soils confirms the predominant role of metallurgy on the general pollution in the area. The highly contaminated soils from the vicinity of the smelter contain up to 35,300 mg Pb kg^–1 and exhibit an isotopic composition close to that of car battery processing (²⁰⁶Pb/²⁰⁷Pb up to 1.177). A coupled concentration/isotopic study of soil profiles showed that the smelter-induced pollution had penetrated even to the mineral soil horizons, indicating an important vertical mobility of Pb contaminant within the soil profile. The calculated downward penetration rate of Pb in soils ranges from 0.3 to 0.36 cm year^–1.     

Precise isotope-ratio measurements of lead species by capillary gas chromatography hyphenated to hexapole Multicollector ICP-MS

The precision and accuracy of lead isotope-ratio determination on a short transient signal has been assessed by coupling capillary gas chromatography to the Isoprobe (Micromass, UK), a single-focusing inductively coupled plasma mass spectrometer with multicollector detection. A T-piece connecting the GC transfer line to the torch enabled continuous aspiration of thallium solution for mass-bias correction. The volatile lead species PbEt4 was derivatized from NIST isotopic certified lead standard SRM 981 and different amounts of PbEt4 dissolved in iso-octane were injected into the GC. Chromatograms were recorded in multicollection mode by use of Faraday cups; seven isotopes (204Pb, 206Pb, 207Pb, 208Pb,     

Charged particle activation analysis applied to the detection of heavy elements

Trace analysis methods have been developed for determining thallium, lead and bismuth. Proton or deuteron activation is used followed by a radiochemical separation of the reaction products:²⁰³Pb from thallium,²⁰⁶Bi from lead, and²⁰⁷Po from bismuth. Activation curves are presented for different nuclear reactions occuring on the elements studied. Determinations have been carried out on high purity samples containing varying amounts of thallium, lead, and bismuth. Based on experimental data, the detection limits are estimated at 0.01 ppm for lead, and 0.001 ppm for thallium and bismuth, respectively.     

Isotopic Characterization of Lead in the Scottish Upland Environment

Abstract

Experimental plots have been set up at two Research Stations in upland areas of Scotland with the intention of characterising environmental samples using lead isotopic composition which varies according to the original source of the lead. Thermal ionisation mass spectrometry (TIMS) was used to measure lead isotope ratios with high precision. The ²⁰⁶Pb/²⁰⁷Pb ratios in rainwater were in the range from 1.101 to 1.153 over a period of two years at the two sites. Low ratios were associated with the very low ratios found in Britain in petrol additives during that period whereas higher ratios indicated a larger component derived from industrial sources at the Hartwood site. The ²⁰⁶Pb/²⁰⁷Pb ratios in the surface (0–2.5 cm) soil from a roadside plot were low (1.1126 and 1.1159 in 1989 and 1990, respectively) but the ratios in surface soils in plots distant from the road were considerably higher. Whereas the lead in roadside soil had a ²⁰⁶Pb/²⁰⁷Pb ratio indicating its source to be predominantly in recent petrol lead, there were significant components from other sources in the soils away from the road. The washing of grass samples resulted in no significant change in the lead isotope ratios. The lead isotope ratios measured in grass samples reflect the isotopic character of current atmospheric inputs but those in surface soil samples are an integrated record of atmospheric deposition over a long period of time. An undisturbed plot under a tree canopy had high concentrations of lead in the surface soil and low ²⁰⁶Pb/²⁰⁷Pb ratios. The ratios in fallen leaves on this plot were slightly but significantly lower than those in the grass grown on the plot. It would appear that the tree canopy is effective at scavenging lead carried in the atmosphere.     

Isotopic fingerprint method: Assessment of the origin of rare earth compounds from the isotope ratios of lead impurities

The isotope ratios ²⁰⁷Pb:²⁰⁶Pb and ²⁰⁸Pb: ²⁰⁶Pb are measured by means of inductively coupled plasma mass spectrometry (ICP-MS) for monazite minerals and commercial rare earth compounds and are evaluated with respect to the initial composition of the minerals and the origin of the samples. The application of the isotopic fingerprint method is demonstrated.Dedicated to Professor Dr. Dieter Klockow on the occasion of his 60th birthday     

Lead isotopic analysis of infant bone tissue dating from the Roman era via multicollector ICP–mass spectrometry

Archaeological samples originating from a cemetery of a Roman settlement, Pretorium Agrippinae (1st–3rd century A.D.), excavated near Valkenburg (The Netherlands) have been subjected to Pb isotopic analysis. The set of samples analysed consisted of infant bone tissue and possible sources of bone lead, such as the surrounding soil, garum, and lead objects (e.g., water pipes). After sample digestion with quantitative Pb recovery and subsequent quantitative and pure isolation of lead, the Pb isotopic composition was determined via multicollector ICP–mass spectrometry. The Pb isotope ratio results allowed distinction of three groups: bone, soil, and lead objects + garum. The ²⁰⁸Pb/²⁰⁶Pb ratio ranges were between 2.059 and 2.081 for the soils, between 2.067 and 2.085 for the bones, and between 2.087 and 2.088 for the lead objects. The garum sample is characterised by a ²⁰⁸Pb/²⁰⁶Pb ratio of 2.085. The bone group is situated on the mixing line between the soil and lead object groups, allowing the statement that diagenesis is not the main cause of the Pb found in the bones.      

应用多接收器电感耦合等离子体质谱法测定海洋碳酸盐中稳定铅同位素组成

研究了多接收器电感耦合等离子体质谱仪(MC-ICP MS)测定铅同位素比值时,影响测试结果准确度和精密度的主要因素及其优化过程。在优化条件下,10 h内连续30次测定4 ng/mL NIST SRM 981同位素标准溶液铅同位素比值,获得208Pb/206Pb、207Pb/206Pb和206Pb/204Pb相对标准偏差(RSDs)分别为0.005%、0.004%和0.054%。长期监测208Pb/206Pb、207Pb/206Pb和206Pb/204Pb,标准偏差(2SDs)分别为0.000 06、0.000 05和0.006 7。采用NEPTUNE MC-ICP MS法测定了低铅海洋碳酸盐样品中稳定铅的同位素比值,并对南海橙黄滨珊瑚(Porites lutea)和库氏砗磲(Tridacna gigas)进行了分析,得到全流程空白为8～10 pg,重复样误差优于0.1%。经0.50 mol/L HNO3洗脱之后,得到海南珊瑚样品中208Pb/206Pb、207Pb/206Pb的比值分别为2.086 2±0.001 5、0.849 90±0.001 47(n=16);海南砗磲样品中208Pb/206Pb、207Pb/206Pb的比值分别为2.116 9±0.004 2、0.864 81±0.001 62(n=9)。进一步考察了南海海洋碳酸盐中204Pb的同位素比值。分析结果表明,南海海洋碳酸盐中稳定铅同位素比值与中国气溶胶、珠江三角洲大气沉降、黄土及南海海底玄武岩等具有很好的相关性。方法适用于复杂基体高钙低铅的海洋碳酸盐样品中铅同位素比值的分析。     

Application of laser ablation multicollector inductively coupled plasma mass spectrometry for the measurement of calcium and lead isotope ratios in packaging for discriminatory purposes

The potential of high‐precision calcium and lead isotope ratio measurements using laser ablation coupled to multicollector inductively coupled plasma mass spectrometry (LA‐MC‐ICP‐MS) to aid distinction between four genuine and five counterfeit pharmaceutical packaging samples and further classification of counterfeit packaging samples has been evaluated. We highlight the lack of reference materials for LA‐MC‐ICP‐MS isotope ratio measurements in solids. In this case the problem is minimised by using National Institute of Standards and Technology Standard Reference Material (NIST SRM) 915a calcium carbonate (as solid pellets) and NIST SRM610 glass disc for sample bracketing external standardisation. In addition, a new reference material, NIST SRM915b calcium carbonate, has been characterised in‐house for Ca isotope ratios and is used as a reference sample. Significant differences have been found between genuine and counterfeit samples; the method allows detection of counterfeits and aids further classification of packaging samples. Typical expanded uncertainties for measured‐corrected Ca isotope ratio values (⁴³Ca/⁴⁴Ca and ⁴²Ca/⁴⁴Ca) were found to be below 0.06% (k = 2, 95% confidence) and below 0.2% for measured‐corrected Pb isotope ratios (²⁰⁷Pb/²⁰⁶Pb and ²⁰⁸Pb/²⁰⁶Pb). This is the first time that Ca isotope ratios have been measured in packaging materials using LA coupled to a multicollector (MC)‐ICP‐MS instrument. The use of LA‐MC‐ICP‐MS for direct measurement of Ca and Pb isotopic variations in cardboard/ink in packaging has definitive potential to aid counterfeit detection and classification. Copyright © 2010 John Wiley & Sons, Ltd.     

Source identification of Pb in aerosols at Jeju-do, Korea by using 207Pb/206Pb and 208Pb/206Pb

Aerosols and source related materials (fly ash from refuse incinerators, vehicle exhaust and soil) were collected in April, 2002 in the northern areas of Jeju-do, Korea, and the Pb isotopic ratios (²⁰⁷Pb/²⁰⁶Pb and ²⁰⁸Pb/²⁰⁶Pb) of the samples were measured in order to estimate the Pb sources of the aerosols. The Pb isotopic ratios of the aerosols were classified into two groups, depending on the sampling date. One group showed similar Pb isotopic ratios with those of the source related materials, suggesting that the contribution of the regional sources to the aerosols was very large. The other showed different Pb isotopic ratios from those of the regional sources and relatively high Pb isotopic ratios compared to the ratios of the first group. The results suggest that in the continental Asia there seems to be a long range transport of Pb with high ratios in desert sands, which are carried by northwest seasonal winds. This revised version was published online in July 2006 with corrections to the Cover Date.     

Evaluation of the combined measurement uncertainty in isotope dilution by MC-ICP-MS

The combination of metrological weighing, the measurement of isotope amount ratios by a multicollector inductively coupled plasma mass spectrometer (MC-ICP-MS) and the use of high-purity reference materials are the cornerstones to achieve improved results for the amount content of lead in wine by the reversed isotope dilution technique. Isotope dilution mass spectrometry (IDMS) and reversed IDMS have the potential to be a so-called primary method, with which close comparability and well-stated combined measurement uncertainties can be obtained.This work describes the detailed uncertainty budget determination using the ISO-GUM approach. The traces of lead in wine were separated from the matrix by ion exchange chromatography after HNO(3)/H(2)O(2) microwave digestion. The thallium isotope amount ratio ( n((205)Tl)/ n((203)Tl)) was used to correct for mass discrimination using an exponential model approach. The corrected lead isotope amount ratio n((206)Pb)/ n((208)Pb) for the isotopic standard SRM 981 measured in our laboratory was compared with ratio values considered to be the least uncertain. The result has been compared in a so-called pilot study "lead in wine" organised by the CCQM (Comité Consultatif pour la Quantité de Matière, BIPM, Paris; the highest measurement authority for analytical chemical measurements).The result for the lead amount content k(Pb) and the corresponding expanded uncertainty U given by our laboratory was:k(Pb)=1.329 x 10-10mol g-1 (amount content of lead in wine)U[k(Pb)]=1.0 x 10-12mol g-1 (expanded uncertainty U=kxuc, k=2)The uncertainty of the main influence parameter of the combined measurement uncertainty was determined to be the isotope amount ratio R(206,B) of the blend between the enriched spike and the sample.     

High-precision measurements of seawater Pb isotope compositions by double spike thermal ionization mass spectrometry

A new method for the determination of seawater Pb isotope compositions and concentrations was developed, which combines and optimizes previously published protocols for the separation and isotopic analysis of this element. For isotopic analysis, the procedure involves initial separation of Pb from 1 to 2 L of seawater by co-precipitation with Mg hydroxide and further purification by a two stage anion exchange procedure. The Pb isotope measurements are subsequently carried out by thermal ionization mass spectrometry using a ²⁰⁷Pb–²⁰⁴Pb double spike for correction of instrumental mass fractionation. These methods are associated with a total procedural Pb blank of 28 ± 21 pg (1sd) and typical Pb recoveries of 40–60%. The Pb concentrations are determined by isotope dilution (ID) on 50 mL of seawater, using a simplified version of above methods. Analyses of multiple aliquots of six seawater samples yield a reproducibility of about ±1 to ±10% (1sd) for Pb concentrations of between 7 and 50 pmol/kg, where precision was primarily limited by the uncertainty of the blank correction (12 ± 4 pg; 1sd). For the Pb isotope analyses, typical reproducibilities (±2sd) of 700–1500 ppm and 1000–2000 ppm were achieved for ²⁰⁷Pb/²⁰⁶Pb, ²⁰⁸Pb/²⁰⁶Pb and ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb, ²⁰⁸Pb/²⁰⁴Pb, respectively. These results are superior to literature data that were obtained using plasma source mass spectrometry and they are at least a factor of five more precise for ratios involving the minor ²⁰⁴Pb isotope. Both Pb concentration and isotope data, furthermore, show good agreement with published results for two seawater intercomparison samples of the GEOTRACES program. Finally, the new methods were applied to a seawater depth profile from the eastern South Atlantic. Both Pb contents and isotope compositions display a smooth evolution with depth, and no obvious outliers. Compared to previous Pb isotope data for seawater, the ²⁰⁶Pb/²⁰⁴Pb ratios are well correlated with ²⁰⁷Pb/²⁰⁶Pb, underlining the significant improvement achieved in the measurement of the minor ²⁰⁴Pb isotope.