Quadrupole ICP-MS Research Articles

Uncertainty contributions to the measurement of dissolved Co, Fe, Pb and V in seawater using flow injection with solid phase preconcentration and detection by collision/reaction cell—quadrupole ICP–MS

A flow injection manifold incorporating a solid phase chelating resin (Toyopearl AF-Chelate-650) is reported for the preconcentration of dissolved metals from seawater, with a focus on investigating the effect of the loading pH, wash solution composition and wash time. Cobalt, iron, lead and vanadium have been used as target analytes with contrasting oceanographic behaviour. Quadrupole ICP–MS has been used for detection to make the approach accessible to most laboratories and a collision/reaction cell has been incorporated to minimise polyatomic interferences. Results for the seawater CRM NASS-6 and two GEOTRACES reference materials were in good agreement with the certified/consensus values, demonstrating the suitability of the approach for the determination of trace metals in seawater. The experimental design used allowed a thorough investigation of the uncertainty contribution from each method parameter to the overall expanded uncertainty of the measurement. The results showed that the parameters making the largest contributions were the precision of the peak area measurement and the uncertainty associated with the slope of the calibration curve. Therefore, these are the critical parameters that should be targeted in order to reduce the overall measurement uncertainty. For iron, the wash blank also gave a measureable contribution.

In vivo penetration of bare and lipid-coated silica nanoparticles across the human stratum corneum

Skin penetration of silica nanoparticles (NP) currently used in pharmaceutical and cosmetic products is a topic of interest not only to evaluate their possible toxicity, but also to understand their behaviour upon contact with the skin and to exploit their potential positive effects in drug or cosmetic delivery field. Therefore, the present work aimed to elucidate the in vivo mechanism by which amorphous hydrophilic silica NP enter human stratum corneum (SC) through the evaluation of the role played by the nanoparticle surface polarity and the human hair follicle density. Two silica samples, bare hydrophilic silica (B-silica, 162±51nm in size) and hydrophobic lipid-coated silica (LC-silica, 363±74nm in size) were applied on both the volar and dorsal side of volunteer forearms. Twelve repetitive stripped tapes were removed from the human skin and evaluated for elemental composition by Energy Dispersive X-ray (EDX) analysis and for silicon content by Inductively Coupled Plasma quadrupole Mass Spectrometry (ICP-MS). All the stripped tapes revealed nanosized structures generally located in the broad spaces between corneocytes and characterized by the same elemental composition (relative weight percentage of silicon and silicon to oxygen weight ratio) than that of the applied samples. However, only about 10% B-silica permeated until the deepest SC layers considered in the study indicating a silica retention in the upper layers of SC, regardless of the hair follicle density. Otherwise, the exposure to LC-silica led to a greater silica skin penetration extent into the deeper SC layers (about 42% and 18% silica following volar and dorsal forearm application, respectively) indicating that the NP surface polarity played a predominant role on that of their size in determining the route and the extent of penetration.

Lead isotope ratios in bone ash of blesbok (Damaliscus pygargus phillipsi): A means of screening for the accumulation of contaminants from uraniferous rocks

This study was done to determine whether blesbok (Damaliscus pygargus phillipsi) from the Krugersdorp Game Reserve (KGR) in Gauteng Province, South Africa have higher concentrations of 238U and higher 206Pb/204Pb and 207Pb/204Pb ratios in their bone ash than blesbok from a nearby control reserve that is not exposed to mine water and has no outcrops of uraniferous rocks. Eight blesbok females from the KGR and seven from the control site, all killed with a brain shot, were used. A Thermo X-series 2 quadrupole ICPMS was used to measure the concentrations of 238U and lead and a Nu Instruments NuPlasma HR MC-ICP-MS to measure the lead isotope ratios in the tibial ash from each animal. KGR blesbok had higher mean concentrations of 238U (P = 0.02) and ratios of 206Pb/204Pb and 207Pb/204Pb (P < 0.00001) than the control blesbok. The probability of rejecting the false null hypothesis of no difference in the 206Pb/204Pb or 207Pb/204Pb ratios between KGR and control reserve animals (the power of the test) was 0.999. The blesbok from the KGR accumulated contaminants from an uraniferous environment. The 206Pb/204Pb and 207Pb/204Pb ratios in tibial ash proved effective in confirming accumulation of contaminants from uraniferous rocks.

Using ICP-qMS to trace the uptake of nanoscale titanium dioxide by microalgae–potential disadvantages of vegetable reference material

As nanoscale materials have gained in economic importance over recent years, concerns about accumulation in the environment and, consequently, analysis of nanoparticles in biological material have increasingly become the focus of scientific research. A nanomaterial used in a wide range of food, consumer and household products is titanium dioxide (nTiO2). Monitoring of nTiO2 via determination of elemental titanium (Ti) can be very challenging because of a variety of possible interferences. This work describes problems during the development of a quantification method for titanium dioxide (TiO2) using inductively coupled plasma-quadrupole mass spectrometry (ICP-qMS). To evaluate the analytical method, certified vegetable reference material NCS DC 73349 was used. Interestingly, measurements of NCS DC 73349 seemed to result in acceptable recovery values-however, this was without considering interferences or conceivable differences in the natural isotopic abundance of the certified titanium calibration solution and NCS DC 73349. Actually, recoveries were lower than initially assumed. The potential interferences causing augmented recovery could be attributed to the presence of the elements sulfur (S) and phosphorus (P), which were able to form oxide ions and nitrogen-interfering species. The effect of such interfering cluster ions could be prevented by dry ashing as a sample preparation step, to evaporate S and P, before digestion with aqua regia in a high-pressure asher (HPA). Final practicability of the analysis method was proved by monitoring the uptake of nTiO2 by the microalgae Scenedesmus acutus in an environmental exposure study.

Simultaneous speciation of selenoproteins and selenometabolites in plasma and serum by dual size exclusion-affinity chromatography with online isotope dilution inductively coupled plasma mass spectrometry

A method for the simultaneous speciation of selenoproteins and selenometabolites in mouse plasma has been developed based on in series two-dimensional size exclusion and affinity high-performance liquid chromatography (2D/SE-AF-HPLC), using two columns of each type, and hyphenation to inductively coupled plasma-(quadrupole) mass spectrometry (ICP-QMS). The method allows the quantitative determination of selenoprotein P (SeP), extracellular glutathione peroxidase (eGPx), selenoalbumin (SeAlb), and selenometabolites in mouse plasma using species-unspecific isotope dilution (SUID). The 2D chromatographic separation is proposed to remove typical spectral interferences in plasma from chloride and bromide on (77)Se ((40)Ar(37)Cl) and (82)Se ((81)Br(1)H). In addition, the approach increases chromatographic resolution allowing the separation of eGPx from Se metabolites of low molecular mass. The method is robust, reliable, and fast with a typical chromatographic runtime less than 20 min. Precision in terms of relative standard deviation (n = 5) is in the order of 4 %, and detection limits are in the range of 0.2 to 1.0 ng Se g(-1). Method accuracy for determination of total protein bound to Se was assessed by analyzing human serum reference material (BCR-637) certified for total Se content, and latterly applied to mouse plasma (Mus musculus). In summary, a reliable speciation method for the analysis of eGPx, selenometabolites, SeP, and SeAlb in plasma/serum samples is proposed for the first time and is applicable to the evaluation of Se status in human in clinical studies and other mammals for environmental or toxicological assessment.

Simple Analysis Method for Metallothionein-1, -2 and -3 in the Brain by One-Step Size-Exclusion Column HPLC On-Line Coupling with Inductively Coupled Plasma Mass Spectrometry

A simple analysis method of metallothionein (MT) isoforms MT-1, MT-2, and MT-3 was developed based on the use of one-step size-exclusion column (SEC) HPLC and on-line coupling with inductively coupled plasma mass spectrometry (ICP-MS). For the elucidation of the functions of MT isoforms in the brain, it is necessary to have a simple method to determine these isoforms. A SEC TSK gel G2000 SWXL PEEK (7.8 mm I.D. × 30 cm) system was used in this study. The HPLC system was connected with a quadrupole ICP-MS. All of the connections were made using PEEK tubing. To induce MTs, cadmium (Cd) chloride was administered to MT-1, 2 null and 129/Sv mice at a dose of 4 mg/kg body weight by i.p. injection. Mice were sacrificed 24 h after treatment under anesthesia. Brains and livers were collected, and all the samples were stored at −80°C until subsequent analyses. Soluble extracts of the livers and brains from 129/Sv mice either treated with cadmium or untreated were analyzed. MT-1, MT-2, and MT-3 were clearly separated by the one-step SEC HPLC-ICP-MS system (monitored at 65Cu, 66Zn, 113Cd and 55Mn for element) using an appropriate buffer (25 mM Tris-12.5 mM HCl containing 20 mM KCl) and an ultrafiltration membrane filter to eliminate high molecular weight proteins over 30,000 MW and Cu, Zn-SOD. Retention times (RTs) of peaks of each isoform were distinguishable; RTs of MT-1, MT-2, and rMT-3 were 8.6, 8.1, and 7.6 min, respectively. MT-1, MT-2, and MT-3 were separated clearly using this system. This system would be a powerful tool for the separation and metal-component analysis of MT isoforms to elucidate further the biological functions of MTs in the brain.

Fast and simple multi-element determination of essential and toxic metals in whole blood with quadrupole ICP-MS

The development of reliable and sensitive methods for elements quantification in low-level concentration is a necessary requirement to detect increases or deficiencies considered unusual in human body. In this sense the sensitivity and selectivity of mass spectrometric methods are particularly appropriate to deal with this issue since many elements in biological material are at extremely low concentration levels and necessity to be monitored. Simultaneous determination of Be, Bi, Ba, Pb, Pd, Pt, Rh, Ni, V, Cr, Mn, As, Cd, Mo, Co, Hg, Tl, Sr, Sb, Se, Cu and Zn in whole blood by ICP-MS is described. Sample preparation consisted of a simple dilution (twenty-fold) with 0.05% Triton X-100 in 0.2% HNO3. The method proved to be accurate (accuracy ranged from 88.9% to 108%), precise (CV was below 5% for all elements) and sensitive (LOQ were below 1 µg L-1 for most of the studied elements). Use of DRC was only necessary for chromium and vanadium determination in blood. The proposed method uses low quantities of blood and this feature is essential when analyzes involve human biological samples. The obtained results show the applicability of the developed methodology for the rapid, sensitive and simultaneous determination of inorganic constituents in whole blood.

Fluid inclusion measurements by laser ablation sector-field ICP-MS

The performance of a sector field ICP-MS in comparison with a quadrupole ICP-MS for fluid inclusion analysis has been evaluated.

Development of a new column switching method for simultaneous speciation of selenometabolites and selenoproteins in human serum

A method for the simultaneous speciation of selenoproteins and selenometabolites in human serum has been developed on the basis of in series three dimensional chromatography: size exclusion, affinity and anion exchange high performance liquid chromatography (3D/SE-AF-AEC-HPLC), using different columns of each type and hyphenation to inductively coupled plasma-(quadrupole) mass spectrometry (ICP-qMS). The method allows the quantitative simultaneous analysis of selenoprotein P (SeP), extracellular glutathione peroxidase (eGPx), selenoalbumin (SeAlb), selenite and selenate in human serum using species-unspecific isotope dilution (SUID). The 3D chromatographic separation is proposed to remove typical spectral interferences in this matrix from chloride and bromide on 77Se (40Ar37Cl), 80Se (79Br1H) and 82Se (81Br1H). In addition, a previous method based on 2D/SE-AF-HPLC is proposed as a simple alternative when low molecular mass selenium species are absent in the samples. The method is robust, reliable and fast with typical chromatographic runtime less than 35min. Detection limits are in the range of 0.2–1.3ng of Seg−1. Method accuracy for determination of total protein-bound to Se was assessed by analyzing an human serum reference material (BCR-637) certified for total Se content and method reliability checked in samples of human serum providing results in good agreement with the total selenium concentration. In addition, the application of the method to commercial human serum and plasma reference materials for quality control analysis, certified for total Se, has provided, for the first time, indicative levels of selenium containing proteins in these samples.

Removal of the gadolinium interference from the measurement of selenium in human serum by use of collision cell quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS)

Measurement of selenium in serum is an important clinical biomarker of nutritional status. The presence of gadolinium (Gd) in samples following administration of the contrast agents used for magnetic resonance imaging (MRI) results in a significant positive bias when using quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS). Three instrumental set-ups were assessed: standard mode with no collision gas and collision cell mode with either a hydrogen:helium mixture or hydrogen. The effect of Gd on the selenium (Se) signal was assessed using external quality assurance (EQA) specimens and internal quality control (IQC) materials, both unspiked and spiked with Gd. Serum previously shown to contain high concentrations of Gd-containing contrast agents were also analysed. Recoveries of Se in the spiked compared to the unspiked samples were: between 500% and 1300% using standard mode; 100% and 29,000% using collision cell mode with hydrogen:helium mixture; and between 99% and 103% using hydrogen. The use of H2 in the collision cell provided accurate results, indicating that the charge exchange reaction (CER) of Gd(2+) with H2 removes this interference. Analysis of patient serum known to contain the Gd contrast agent using the method gave results within the selenium reference range (adults 0.89-1.65 µmol/L). The presence of Gd, as low as 0.2 mg/L, in serum samples causes a positive interference on the measurement of Se by ICP-MS. Using a CER mode with pure H2 in the collision cell it was possible to fully remove the interference due to Gd(2+) from the signal for Se.

An integrated experimental-modeling approach to study the acid leaching behavior of lead from sub-micrometer lead silicate glass particles

This work focuses on the development of a procedure to study the mechanism of leaching of lead from sub-micrometer lead glass particles using 0.3moll−1 HNO3 as a leachant. Glass particles with an effective size distribution range from 0.05 to 1.4μm were generated by laser ablation (213nm Nd:YAG laser) and collected on an inline 0.2μm syringe filter. Subsequently, the glass particles on the filter were subjected to online leaching and continuous monitoring of lead (Pb-208) in the leachate by quadrupole ICP-MS. The lead leaching profile, aided by the particle size distribution information from cascade impaction, was numerically fitted to a mathematical model based on the glass intraparticle diffusion, liquid film distribution and thermodynamic glass-leachant distribution equilibrium. The findings of the modeling show that the rate-limiting step of leaching is the migration of lead from the core to the surface of the glass particle by an ion-exchange mechanism, governed by the apparent intraparticle lead diffusivity in glass which was calculated to be 3.1×10−18m2s−1. Lead leaching is illustrated in the form of graphs and animations of intraparticle lead release (in time and intraparticle position) from particles with sizes of 0.1 and 0.3μm.

Determination of Impurities in High Purity Germanium by Inductively Coupled Plasma Quadrupole Mass Spectrometry (ICP-QMS) After Matrix Volatilization Using Chlorine Gas

Determination of Impurities in High Purity Germanium by Inductively Coupled Plasma Quadrupole Mass Spectrometry (ICP-QMS) After Matrix Volatilization Using Chlorine Gas

Simultaneous determinations of zirconium, hafnium, yttrium and lanthanides in seawater according to a co-precipitation technique onto iron-hydroxide

Very low concentrations (pg mL(-1) or sub-pg mL(-1) level) along with the high salinity are the main problems in determining trace metal contents in seawater. This problem is mainly considered for investigations of naturally occurring YLOID (Y and Lanthanides) and Zr and Hf in order to provide precise and accurate results. The inductively coupled plasma mass spectrometry (ICP-MS), both in high and low resolution, offers many advantages including simultaneous analyses of all elements and their quantitative determination with detection limits of the order of pg mL(-1). However in the analysis of YLOID in seawater, a better determination needs an efficient combination of ICP-MS measurement with a pre-concentration technique. To perform an ultra-trace analysis in seawater, we have validated an analytical procedure involving an improved modified co-precipitation on iron hydroxides to ensure the simultaneous quantitative recovery of YLOID, Zr and Hf contents with measurement by a quadrupole ICP-MS. The validity of the method was assessed through a series of co-precipitation experiments and estimation of several quality control parameters for method validation, namely working range and its linearity, detection limit, quantification limit, precision and spike recoveries, and the methodological blank choice, are introduced, evaluated and discussed. Analysis of NASS-6, is the first report on the latest seawater reference material for YLOID, hafnium and zirconium.

A New Major Adze Quarry from Nānākuli, O‘ahu: Implications for Interaction Studies in Hawai‘i

A major new basalt adze quarry at Nānākuli Valley, Hawaiian Islands is described which now ranks as one of the two largest on O‘ahu and aside from the Mauna Kea adze quarry complex on Hawai‘i island and the Haleakalā source on Maui, is one of the major quarries in the archipelago. We defined the approximate limits of the quarry complex, located the in situ geological source of the fine-grained basalt used for adze manufacture, report the petrographic and geochemical variability of the source rock, and describe the adze reduction strategies from analysis of adze blanks andpreforms, as well as hammerstones and debitage. The geochemical variation of the nine source rocks and artefacts were defined by a comprehensive array of 10 fully quantitative major element concentrations, 43 trace element abundances, and high-precision Sr-Nd-Pb isotopic ratios obtained using the state-of-the-art Thermal Ionization Mass Spectrometry (TIMS, for Sr isotopes), Multi-Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS, for Nd-Pb isotopes), quadrupole ICP-MS (for trace elements) and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES, for major elements), respectively. A piece of branch coral was recovered from the surface of a rockshelter that provided a U-series date of possible quarry use in the mid-13th century. It is advocated that a comprehensive range of major and trace element concentrations and Sr-Nd-Pb isotopic ratios are required for geochemically characterising adze quarries to facilitate the long-term viability of sourcing studies.

Development of a 2D laser ablation inductively coupled plasma mass spectrometry mapping procedure for mercury in maize (Zea mays L.) root cross-sections

A LA-ICP-MS method based on a 213nm Nd:YAG laser and a quadrupole ICP-MS has been developed for mapping of mercury in root cross-sections of maize (Zea mays L.) to investigate the mechanism of mercury uptake from soil and its potential translocation to the edible parts. Conventional rastering was found to be unusable due to sorption of mercury onto the internal parts of the LA device, giving rising to memory effects resulting in serious loss of resolution and inaccurate quantification. Spot analysis on a virtual grid on the surface of the root sections using washout times of 10s in between spots greatly alleviated problems related to these memory effects. By ablating straight through the root sections on a poly(methyl methacrylate) support the calibration process was simplified as internal standardization and matrix-matching could be circumvented. Mercury-spiked freeze-drying embedding medium, sectioned similarly to the root sections, was used for the preparation of the standards. Standards and root sections were subjected to spot analysis using the following operational parameters: beam diameter, 15μm; laser fluence, 2.5Jcm−2; repetition rate, 20Hz; dwell time, 1s; acquisition time, 0.1s. The mercury peaks for standards and roots sections could be consistently integrated for quantification and construction of the 2D mercury maps for the root sections. This approach was successfully used to investigate the mercury distribution in root sections of maize grown in soil spiked to a level of 50mgkg−1 DW HgCl2. It was found that at given Hg concentrations in the substrate Hg ions practically do not cross root plasma membranes of the endodermal barrier, but are entirely retained in the root apoplastic space. This suggests that maize plants grown in Hg-contaminated areas translocate Hg to the upper edible parts of the plant only to a small extent.

Determination of ultratrace amounts of plutonium in high saline groundwater by inductively coupled plasma mass spectrometry

For determination of ultratrace amounts of plutonium in high saline groundwater, large-volume sampling and preconcentration are necessary. However, traditional co-precipitation methods, such as Fe(OH)3, Ca(OH)2–Mg(OH)2 and hydroxide-carbonate co-precipitation, are unable to meet the requirements of preconcentration of the ultratrace plutonium in high saline groundwater. In this paper, the ultratrace plutonium in high saline groundwater was concentrated by sequential co-precipitation with MnO2 and Fe(OH)3, and purified by two-stage anion-exchange separation on Dowex1 × 4 resin column. Quadrupole ICP-MS was employed for the determination of 239Pu with 242Pu spiked. After co-precipitation and purification, the major matrix elements were significantly decreased to μg mL−1 level and decontamination factor of uranium is better than 106. The detection limit for 239Pu in 50 L high saline water is 2.1 × 10−16 g L−1. Three high saline fountain samples (total dissolved solids more than 20 g L−1) from Dunhuang region of China were analyzed using this method. The concentrations of 239Pu in these samples were 0.48 ± 0.2 × 10−15, 1.40 ± 0.10 × 10−15 and 2.13 ± 0.21 × 10−15 g L−1 respectively. The recovery obtained for 7 pg of 242Pu spiked into real high saline-water samples was all above 70 %.

Trace metal chemistry in the pristine freshwater Lake Hauroko, Fiordland, New Zealand

The south-western region of the South Island of New Zealand is remote from human activities and is thought to be minimally affected by anthropogenic contaminants, making it a good candidate for understanding the geochemistry of pristine systems, and for providing baseline concentrations for trace elements and other chemical parameters. We have determined the inorganic and physical characteristics of a remote mountain lake (Lake Hauroko) in this region. The lake exhibits oligotrophic character and major ion concentrations and total alkalinity are very constant throughout summer and winter as well as with depth. Because of the low ionic strength, trace metal concentrations were measured directly on acidified samples by Quadrupole ICP-MS. Concentrations are low throughout, averaging (in ngl−1) for Mn 102.9, Fe 4570, Co 5.31, Ni 98.6, Cu 247.8, Zn 140.7, Cd 1.23 and Pb 24.85. We have compared these results with other lakes in New Zealand, with freshwater systems in Europe and North America as well as with the temperate stream model of Meybeck (1987). These comparisons confirm the very pristine character of this lake, making it an ideal natural laboratory for the study of natural biogeochemical cycles of trace element and nutrients at temperate latitudes.

Discrimination of Low-alpha 210 Lead for Electronics Material Using Isotope Ratio Measurement by ICP-QMS

The applicability of inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) has been investigated to the discrimination of low-alpha lead raw materials for electronics material. The experimental conditions for ICP-QMS were first optimized to improve the precision of isotope ratio measurement of lead materials. The lead isotope ratios of NIST SRM981 measured by an ICP-QMS under the optimized conditions agreed with those obtained by high precision mass spectrometers, thermal ionization mass spectrometer or multiple collector inductively coupled plasma mass spectrometer within the range of statistical errors. The relationship between the isotope ratios and alpha dose rates measured for six types of lead raw materials in various quality produced by different refining methods revealed that the leads examined here were divided into four groups. The low-alpha lead raw material showed a peculiar isotope ratio and was found to be discriminable by ICP-QMS.

Dispersive liquid–liquid micro extraction of boron as tetrafluoroborate ion (BF4−) from natural waters, wastewater and seawater samples and determination using a micro-flow nebulizer in inductively coupled plasma-quadrupole mass spectrometry

Boron, present in groundwater and seawater, is extracted as tetrafluoroborate anion by dispersive liquid–liquid microextraction (DLLME) and determined 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 tetrafluoroborate anion formed in the presence of 0.9 mol L−1 H2SO4 and 0.1 mol L−1 F− was extracted into chloroform in the presence of Aliquat® 336 (tricaprylmethylammonium chloride) at room temperature. The bulky cationic surfactant, Aliquat® 336, acts as a phase transfer agent, which not only forms an ion-pair complex with tetrafluoroborate anion but also helps in the rapid conversion of boric acid to BF4− ion. The tetrafluoroborate anion was back-extracted from the chloroform layer with nitric acid for determination by ICP-QMS. Effective parameters for the complex formation and its extraction, such as volume of extractant/disperser solvent, extraction time and concentration of the surfactant have been optimized. Under optimum conditions, an average preconcentration factor of 18 was obtained for 8 mL of water sample for determination by ICP-QMS. The calibration graph was linear in the range of 1–50 μg L−1 for boron, with a limit of detection of 0.3 μg L−1, calculated based on 3 s of blank (n = 6). The precision was close to 3% R.S.D. (n = 3), when processing 8 mL aliquots of sample. The method has been applied to determine boron in bottled mineral water, groundwater, wastewater and seawater samples. The recoveries obtained for the boron spiked to 30 μg L−1 levels in these water samples were 97–102%.

Application of mass spectrometric isotope dilution methodology for 90Sr age-dating with measurements by thermal-ionization and inductively coupled-plasma mass spectrometry

Application of an isotope-dilution method for determining 90Zr and 90Sr in a 90Sr source material spiked with 86Sr and 92Zr is described. A miniature gas pressurized extraction chromatography (GPEC) system with a column containing Eichrom Sr Resin™ was used for separating the elements so isobaric isotopes could be measured by mass spectrometry. Zirconium was rinsed through the column with 3 M HNO3/trace HF and strontium was eluted with 1% acetic acid. Two mass spectrometric techniques, inductively coupled plasma mass spectrometry (ICP-MS) and thermal ionization mass spectrometry (TIMS), were used for measuring isotope ratios. Data were obtained with 90Sr from a blood-irradiator source. Results from the TIMS measurements gave a decay time of 45.16 ± 0.26 years, and those from the ICP-MS gave 45.24 ± 0.20 years (uncertainties are expanded uncertainty, k = 2). Quadrupole ICP-MS is preferable to TIMS in this application if the ICP-MS data are suitably corrected for non-linearity and mass discrimination.