High-efficiency Sample Introduction System Research Articles

Assessment of TiO2 (nano)particles migration from food packaging materials to food simulants by single particle ICP-MS/MS using a high efficiency sample introduction system

TiO2 is the most widely used white pigment in plastics and food packaging industry, thus the question of its migration towards food and hence the impact on consumers is raised. Since recent research indicate its potential toxicity, it is necessary to study TiO2 contamination as a consequence of food storage. For this purpose, plastic containers from commercially-available dairy products and custom-made TiO2-spiked polypropylene materials were put in contact with 50% (v/v) ethanol and 3% (w/v) acetic acid, which were used here as food simulants. The migration assays were carried out under standard contact conditions of packaging use (as recommended by Commission Regulation (EU) N° 10/2011 for food contact migration testing), and under conditions of extreme mechanical degradation of the packaging. The TiO2 (nano)particles released in the food simulants were analysed by single particle inductively coupled plasma-tandem mass spectrometry in mass-shift mode and using a high efficiency sample introduction system (APEX™ Ω) to avoid matrix effects from food simulants. For the dairy product containers and for the spiked polypropylene, results showed release of TiO2 particles of rather large sizes (average size: 164 and 175 nm, respectively) under mechanical degradation conditions, i.e. when the polymeric structure is damaged. The highest amounts of TiO2 were observed in 50% ethanol after 10 days of storage at 50 °C (0.62 ng cm−2) for the dairy product containers and after 1 day of storage at 50 °C (0.68 ng cm−2) for the spiked polypropylene. However, the level of Ti released in particle form was very small compared to the total Ti content in the packaging and far below the acceptable migration limits set by European legislation. Release under standard contact conditions of use of the container was not measurable, thus the migration of TiO2 particles from this packaging to dairy products among storage is expected to be negligible.

Characterisation and quantification of titanium dioxide nanoparticles in food simulants by single particle inductively coupled plasma-tandem mass spectrometry using a high efficiency sample introduction system

This article reports the development of a novel method based on single particle inductively coupled plasma-tandem mass spectrometry (ICP-MS/MS) using a high efficiency sample introduction system (HESIS) for the characterisation and quantification of titanium dioxide (nano)particles (TiO2 NPs) in food simulants. The use of the mass-shift mode (O2 + H2 as a mixture reaction gas) avoids the isobaric interferences of 48Ca isotope hence allowing accurate characterisation of TiO2 NPs in complex matrices such the foodstuffs. Two HESIS (APEX™ Q and APEX™ Ω) were compared with the conventional ICP-MS/MS sample introduction system in terms of sensitivity and trueness for the detection of TiO2 NPs in various (organic) food simulants. APEX™ Ω proved to be an excellent approach to avoid matrix effects from food simulants and provided significantly lower limits of detection in size (LODsize) compared to the conventional introduction system. In order to avoid the saturation of the detector when detecting large TiO2 particles (> 300 nm), the analyses were carried out using the forced analogue detection mode and accurate characterisation of TiO2 NPs in terms of size and concentration was achieved, with an average LODsize of 20 nm over 3 days. This confirms the feasibility of this novel approach using an APEX™ Ω for the characterisation and quantification of TiO2 NPs in complex matrices such as the food simulants and its application to real-life studies regarding the migration of TiO2 NPs from food containers into the simulants.

Analysis of microsamples of biological fluids via inductively coupled plasma-tandem mass spectrometry using a micro-flow injection system coupled to a high-efficiency sample introduction setup

In many fields, the sample volume available is the limiting factor for ultra-trace elemental analysis, and thus, the development of novel methods that can extract more information from lower sample amounts is a topic that deserves attention. In this work, the performance of a micro-flow injection system coupled to either (1) a traditional or (2) a high-efficiency sample introduction system has been evaluated for the analysis of liquid microsamples using inductively coupled plasma-mass spectrometry (ICP-MS). The figures of merit with each sample introduction system have been studied in a wide range of sample volumes and sample uptake rates. The use of a high-efficiency low-volume sample introduction system provided a > 4-fold enhanced sensitivity as compared to the traditional one, while the former setup was demonstrated being capable of accurately delivering volumes as low as 5 or 10 μL to the ICP. Even for such low sample amounts, good linearity (>0.9998) and repeatability (RSD down to 0.2%) were experimentally demonstrated, while matrix effects were lower with the high-efficiency sample introduction system. The use of an internal standard adequately corrected for changes in sample introduction conditions, allowing quantitative results to be obtained by using a single set of calibration data obtained at fixed operating conditions (sample volume and sample uptake rate), with a bias <15% (typical acceptance criterion for clinical QC analysis). The set-up characterized was successfully applied to the analysis of microsamples of biological fluids (down to 0.4 μL of sample volume). Tandem ICP-MS (ICP-MS/MS) was used to overcome spectral overlap (chemical resolution with a mixture of NH3/He) affecting the determination of six clinically relevant metals (Co, Cr, Mn, Ni, Ti and V) at ultra-trace concentration levels. No significant differences were found between the results obtained in this work and the reference values, even when using different sample introduction conditions for the measurement of calibration standards and samples.

Rapid Monitoring of 241Am in Small Amount of Sediment Samples by ICP-MS/MS With a High Efficiency Sample Introduction System

Rapid Monitoring of 241Am in Small Amount of Sediment Samples by ICP-MS/MS With a High Efficiency Sample Introduction System

Rapid determination of ultra-trace plutonium in large volume of urine samples by tandem quadrupole inductively coupled plasma-mass spectrometry

Rapid bioassay method for plutonium in urine samples are employed to assess the possible internal dose resulting from exposure to plutonium in the event of a radiological and nuclear emergency. In this work, a rapid method for the determination of plutonium isotopes (239Pu and 240Pu) in large volume of urine samples was developed using tandem quadrupole ICP-MS combined with a high-efficiency sample introduction system (APEX-Ω). The mixture gases of NH3 and He was employed to effectively eliminate the tailing of 238U and the uranium hydride ions (238U1H+and 238U1H2+) and significantly improve the measurement sensitivity of plutonium. The method was validated by analyzing urine samples spiked with known amounts of 239Pu and 240Pu ranging from 1 to 60 fg. The detection limits for the method were estimated to be 0.83 fg for 239Pu, 0.14 fg for 240Pu in 1 L of urine.

A Novel and Simple Method for Elements Determination in Aerobiological Samples by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) Analysis

The identification of heavy metals in the atmosphere has increased a strong and growing interest. Thereby, monitoring of elements in aerobiological samples could be a powerful tool for detection of environmental pollution. In this work, a simple and fast method for the determination of trace metals bound to aeroparticles such as pollen was optimized. A single-step procedure for the dissolution of aerobiological samples in nitric acid and further determination by inductively coupled plasma mass spectrometry (ICP-MS) with a high-efficiency sample introduction system was developed. The procedure involved low dilution and low detection limits with adequate precision and its direct introduction into the ICP-MS system. The novel method proposed was successfully applied to determine five elements in concentrations from 0.04 mg g−1 (U) to 14.1 mg g−1 (Mn) in aerobiological samples. Through this procedure, the most significant correlations between pollen of Cupressaceae, Ulmus, and Moraceae with Mn, and pollen of Moraceae with Pb were found. This methodology could be a very useful tool to assess air pollution. We are not only proposing a new strategy to analyze air samples particles but also giving new information of the elemental composition carried by pollen.

高効率試料導入システムを用いた高時間分解ICP-MSによる単一ナノ粒子・細胞分析

高効率試料導入システムを用いた高時間分解ICP-MSによる単一ナノ粒子・細胞分析

Triple-Quadrupole Inductively Coupled Plasma-Mass Spectrometry with a High-Efficiency Sample Introduction System for Ultratrace Determination of (135)Cs and (137)Cs in Environmental Samples at Femtogram Levels.

High yield fission products, (135)Cs and (137)Cs, have entered the environment as a result of anthropogenic nuclear activities. Analytical methods for ultratrace measurement of (135)Cs and (137)Cs are required for environmental geochemical and nuclear forensics studies. Here we report a highly sensitive method combining a desolvation sample introduction system (APEX-Q) with triple-quadrupole inductively coupled plasma mass spectrometry (AEPX-ICPMS/MS) for the determination of (135)Cs and (135)Cs/(137)Cs isotope ratio at femtogram levels. Using this system, we introduced only selected ions into the collision/reaction cell to react with N2O, significantly reducing the isobaric interferences ((135)Ba(+) and (137)Ba(+)) and polyatomic interferences ((95,97)Mo(40)Ar(+), (119)Sn(16)O(+), and (121)Sb(16)O(+)). Compared to the instrument setup of ICPMS/MS, the APEX-ICPMS/MS enables a 10-fold sensitivity increase. In addition, an effective chemical separation scheme consisting of ammonium molybdophosphate (AMP) Cs-selective adsorption and two-stage ion-exchange chromatographic separation was developed to remove major matrix and interfering elements from environmental samples (10-40 g). This separation method showed high decontamination factors (10(4)-10(7)) for major matrix elements (Al, Ca, K, Mg, Na, and Si) and interfering elements (Ba, Mo, Sb, and Sn). The high sensitivity of APEX-ICPMS/MS and the effective removal sample matrix allowed reliable analysis of (135)Cs and (137)Cs with extremely low detection limits (0.002 pg mL(-1), corresponding to 0.006 Bq mL(-1) (137)Cs). The accuracy and applicability of the APEX-ICPMS/MS method was validated by analysis of seven standard reference materials (soils, sediment, and plants). For the first time, ultratrace determination of (135)Cs and (135)Cs/(137)Cs isotope ratio at global fallout source environmental samples was achieved with the ICPMS technique.

Single-step solubilization of milk samples with N,N-dimethylformamide for inductively coupled plasma-mass spectrometry analysis and classification based on their elemental composition

A single-step procedure for trace elements analysis of milk samples is presented. Solubilization with small amounts of dymethylformamide (DMF) was assayed prior to inductively coupled plasma mass spectrometry (ICPMS) detection with a high efficiency sample introduction system. All main instrumental conditions were optimized in order to readily introduce the samples without matrix elimination. In order to assess and mitigate matrix effects in the determination of As, Cd, Co, Cu, Eu, Ga, Gd, Ge, Mn, Mo, Nb, Nd, Ni, Pb, Pr, Rb, Sm, S, Sr, Ta, Tb, V, Zn, and Zr, matrix matching calibration with 103Rh as internal standard (IS) was performed. The obtained limits of detection were between 0.68 (Tb) and 30 (Zn) μgL−1. For accuracy verification, certified Skim milk powder reference material (BCR 063R) was employed. The developed method was applied to trace elements analysis of commercially available milks. Principal components analysis was used to correlate the content of trace metals with the kind of milk, obtaining a classification according to adults, baby or baby fortified milks. The outcomes highlight a simple and fast approach that could be trustworthy for routine analysis, quality control and traceability of milks.

Single-step procedure for trace element determination in synovial fluid by dynamic reaction cell-inductively coupled plasma mass spectrometry

A fast and single-step procedure for the dissolution of human synovial fluid in formic acid and further determination by dynamic reaction cell-inductively coupled plasma mass spectrometry (DRC-ICPMS) with a high-efficiency sample introduction system was developed. The samples were collected, treated and analyzed in the same screw-capped tubes. In order to overcome the effect of considerable carbon content, the sample introduction, nebulization and ICP operating conditions were carefully optimized. Furthermore, DRC technology with CH4 as reaction gas was used for the elimination of spectral interferences due to polyatomic ions. The effect of the sample matrix was evaluated and mitigated through comparison of direct calibration against aqueous standards, direct calibration in formic acid media and analyte addition calibration. The recommended procedure involved low dilution and low detection limits (from 0.003μgL−1 for U to 13.3μgL−1 for Ti) with adequate precision (from 0.6% for Co to 6.6% for Ti). The proposed method was successfully applied to determine 16 trace elements in concentrations from 0.03μgL−1 (Cd) to 88.2μgL−1 (Cu) in human synovial fluid samples.

Potential of high resolution ICP-OES for elemental and isotopic analysis of americium

The potential of the eleven most sensitive emission wavelengths of americium (Am) for prospective isotopic and elemental analysis was investigated in detail using a commercial high resolution ICP-OES spectrometer. Calibration of the instrumental response was carried out through stepwise dilution of a 241Am stock solution (1 550 mg/kg) that was prepared in-house via chemical separation of the element from a concentrated plutonium (Pu) solution (115 g/L). Sector field ICP-MS and α- and γ-spectrometry served to characterise extensively the employed Am and Pu solutions for their actual concentration, potential impurities and isotopic purity. Hyperfine splitting of relatively broad peaks (~ 10 pm) or multiplets, i.e. multiple peaks, was observed for most tested Am ICP-OES emission signals with 241Am and 243Am revealing identical signal patterns. The isotopic shift between 241Am and 243Am was generally small with a maximum difference of only ~ 3.7 pm found at λ = 450.945 nm and λ = 469.970 nm, respectively. As a consequence, the extraction of Am isotopic information from the ICP-emission spectra was limited. The use of a high efficiency sample introduction system helped to lower detection limits (LOD) for Am up to two orders of magnitude compared to previous values. While the emission wavelength λ = 283.226 nm provided the lowest LOD of 0.07 μg/kg, distinct spectral interferences originating from thorium (Th) (λ = 283.231 nm), would hamper the reliable determination of Am in Th-based nuclear fuels. A detailed interference study highlights the potential and drawback of each investigated emission wavelength for ICP-OES analysis of Am with special emphasis on nuclear fuel samples containing substantial amounts of Th, Pu and U.

Cross-validation of analytical procedures for the reliable determination of Nd concentrations in nuclear fuel using ICP-OES and sector field ICP-MS

This study focussed on the development and validation of straightforward ICP-OES and sector field ICP-MS procedures for the accurate determination of the neodymium (Nd) concentration in nuclear samples. After dissolution of a spent fuel in a chemical hot cell, Nd was analysed in the acidic solution without prior separation of any fission products. In order to improve sensitivity, a high efficiency sample introduction system was coupled to the employed high resolution ICP-OES instrument. The ten most sensitive emission wavelengths of Nd were investigated systematically, all of them yielding detection limits (LODs) of less than 1 μg kg−1. The highest sensitivity and the best LOD of 0.3 μg kg−1 were obtained at the emission lines λ = 401.225 nm and λ = 430.358 nm. Compared to previous studies this LOD is more than one order of magnitude lower while sample consumption (∼0.3 mL min−1) is less than one third of the volume normally required for such analysis. In terms of radioactive samples these improved analytical figures of merit denote a considerably lower dose to the ICP-OES operator and less radioactive waste. Considering sensitivity, potential spectral interferences and stability of the spectral background, the four emission lines at λ = 401.225 nm, λ = 406.109 nm, λ = 410.946 nm and λ = 430.358 nm proved to be most useful for the reliable determination of Nd. In the absence of matrix matched reference materials having a certified Nd concentration, the accuracy of Nd ICP-OES analysis was ascertained by quantification of Nd using both external calibration and the standard addition approach. In addition, sector field ICP-MS analysis of the Nd elemental concentration was also possible without any separation step as the Nd isotopic composition of the spent fuel was well characterised in previous analyses. This new series of ICP-MS analyses was based on the interference-free isotopes 143Nd, 144Nd (a small 144Ce correction was almost negligible), 145Nd and 146Nd, which are also the four main isotopes in fission Nd. The relative isotopic results obtained using sector field ICP-MS confirmed the previously determined Nd isotopic composition. The repeated Nd concentration analysis of the dissolved spent fuel sample applying the developed ICP-OES and ICP-MS procedures gave results that overlapped within their standard deviations, underpinning the reliability of both experimental approaches.

Direct analysis of lanthanides by ICPMS in calcium-rich water samples using a modular high-efficiency sample introduction system–membrane desolvator

Lanthanoids (also known as rare-earth elements – REE) are well-known tracers of water–rock interaction processes due to their behavior being coherent with their atomic radii, and the capability of Ce and Eu to reflect redox conditions. However, analysis of REE in natural waters is hampered by their relatively low concentration (sub-pg g−1), and the concentration of dissolved solids ranging in the hundreds of μg g−1, imposing important matrix effects to the analysis. Because of this, different analytical techniques have been developed to analyze them by Q-ICPMS and SF-ICPMS, which usually involve matrix removal and analyte pre-concentration. Analysis of REE in karstic waters, those naturally saturated in CaCO3, presents an additional challenge due to the presence of high Ba concentrations (several ng g−1) which can bias the analysis due to the formation of BaO+ and BaOH+ ions during ionization, interfering with the mass range of 148–155 m/z+, including both Eu isotopes, and significantly hampering the direct analysis of such samples. Here, using a modular high-efficiency sample introduction system and desolvator we eliminate the formation of BaO+, and significantly reduce BaOH+, allowing us to analyze small samples (1–2 ml) with Ba/Eu ratios as high as 8 × 104 (mol/mol), and up to 600 μg g−1 of Ca, without any sample pretreatment. Our methodology was validated by analyzing VIDAC18 and SERMIN1 reference materials, and permits the quantification of all REE with detection limits ranging between 500 and 30 fg g−1 and with RSD ∼ 10% for 1 pg g−1, controlled by counting statistics.

Contamination of Alpine snow and ice at Colle Gnifetti, Swiss/Italian Alps, from nuclear weapons tests

Plutonium is present in the environment as a consequence of atmospheric nuclear tests, nuclear weapons production and industrial releases over the past 50 years. To study temporal trends, a high resolution Pu record was obtained by analyzing 52 discrete samples of an alpine firn/ice core from Colle Gnifetti (Monte Rosa, 4450 m a.s.l.), dating from 1945 to 1990. The 239Pu signal was recorded directly, without decontamination or preconcentration steps, using an Inductively Coupled Plasma - Sector Field Mass Spectrometer (ICP-SFMS) equipped with an high efficiency sample introduction system, thus requiring much less sample preparation than previously reported methods. The 239Pu profile reflects the three main periods of atmospheric nuclear weapons testing: the earliest peak lasted from 1954/55 to 1958 and was caused by the first testing period reaching a maximum in 1958. Despite a temporary halt of testing in 1959/60, the Pu concentration decreased only by half with respect to the 1958 peak due to long atmospheric residence times. In 1961/62 Pu concentrations rapidly increased reaching a maximum in 1963, which was about 40% more intense than the 1958 peak. After the signing of the Limited Test Ban Treaty between USA and USSR in 1964, Pu deposition decreased very sharply reaching a minimum in 1967. The third period (1967-1975) is characterized by irregular Pu concentrations with smaller peaks (about 20-30% of the 1964 peak) which might be related to the deposition of Saharan dust contaminated by the French nuclear tests of the 1960s. The data presented are in very good agreement with Pu profiles previously obtained from the Col du Dome ice core (by multi-collector ICP-MS) and Belukha ice core (by Accelerator Mass Spectrometry, AMS). Although a semi-quantitative method was employed here, the results are quantitatively comparable to previously published results.

Distribution of plutonium isotopes in sediments of Melanesian Basin, Central Pacific

The anthropogenic plutonium isotopes are important geochemical tracers for environmental studies. The distributions and sources of the Pu isotopes in water column or sediments of the North Pacific have been intensively studied. However, knowledge on the distribu- tion of Pu isotopes in sediments of the Central Pacific, when available, is limited. To study the composition of Pu isotopes in the ocean, thus to identify the sources of radioactive pollution, sediment core samples were col- lected in the Central Pacific by R/V Hakuho Maru in the KH-04-5 cruise. The activity concentrations of 239?240 Pu and the 240 Pu/ 239 Pu atom ratio were determined using a sector-field inductively coupled mass spectrometry (SF-ICP-MS) combined with a high efficiency sample introduction system (APEX-Q). Possible sources and sed- imentation behavior of Pu isotopes are discussed.

Speciation analysis of selenoproteins in human serum by microbore affinity-HPLC hyphenated to ICP-Sector field-MS using a high efficiency sample introduction system

Microbore affinity-HPLC (AF-HPLC) hyphenated to inductively coupled plasma-sector field mass spectrometry (ICP-SFMS) was applied to the simultaneous speciation analysis of glutathione peroxidase (GPx), selenoprotein P (SelP) and seleno-albumin (SeAlb) in 5 μL of (human) serum. ICP-SFMS (high resolution mode, HR, M/ΔM = 10,000) was used for the quantification of selenium in GPx, SelP and SeAlb after their separation by AF-HPLC, without prior sample preparation or mathematical correction of the spectral interferences. In order to compensate for the loss in sensitivity due to the detection in HR mode and the very low amount of sample taken for analysis, a high-efficiency sample introduction system was used as an interface between AF-HPLC and ICP-SFMS. This led to a signal-to-noise ratio enhancement of about one order of magnitude compared to the conventional experimental ICP-SFMS set-up. Apart from the very low sample consumption, another major advantage of the method described here is the significant reduction of the analysis time (≤7 min). Quantification of GPx, SelP and SeAlb was carried out using on-line (post column) isotope dilution; comparison with on-line external calibration by using Se-L-cystine standard is also addressed. The method accuracy for the determination of total protein bound Se was assessed by the analysis of a human serum reference material (BCR-637) certified for total Se content.

A high-efficiency sample introduction system for capillary electrophoresis analysis of amino acids from dynamic samples and static dialyzed human vitreous samples

A low-volume automated injection system for the analysis of chemically complex, amino acid samples is presented. This system utilizes submicroliter sample volumes stored on a 75-mum inner diameter capillary. A pulse of positive pressure (82 kPa) is used to load nanoliter sample volumes into an in-house fabricated interface and onto a separation capillary. Residual sample solution in the interface is immediately washed away by a continuous transverse flow through the injection interface, yielding a sharp and reproducible sample plug. By performing multiple injections of a static sample, one may average the signals to yield a signal-to-noise ratio improvement of up to 4.07-fold for 20 injections compared with a theoretical maximum of a 4.47-fold improvement. Without interruption of the applied voltage, injections performed every 150 s were used to monitor the progress of the reaction of multiple amino acids with the fluorogenic dye 3-(4-carboxybenzoyl)quinoline-2-carboxaldehyde. Analysis of dialyzed clinical vitreous samples demonstrates the resolution and quantitation of arginine, lysine, leucine, glutamine, and glutamate. Observed levels are comparable with those of nonautomated injection methods and reports by others.

Isotope dilution sector-field inductively coupled plasma mass spectrometry combined with extraction chromatography for rapid determination of 241Am in marine sediment samples: A case study in Sagami Bay, Japan

241Am is a useful tracer for understanding biogeochemical processes in the marine environment. 241Am also poses a potential radiation threat to human health due to the continuous increase of its concentration in the global environment. We report a rapid analytical method for determining 241Am in marine sediments using isotope dilution sector-field inductively coupled plasma mass spectrometry (SF-ICP-MS) combined with a high-efficiency sample introduction system (APEX-Q). A selective CaF2 co-precipitation procedure followed by TRU extraction chromatography was employed to effectively remove the major sediment matrix and to pre-concentrate 241Am. We achieved an extremely low detection limit of 0.32 fg/g or 0.041 mBq/g (for 1 gram sediment), which is better than that of alpha spectrometry, and it allowed the accurate determination of 241Am in low-level marine sediment samples. The accuracy and precision of the developed analytical method was evaluated using a laboratory prepared Am isotope standard solution and Ocean Sediment reference material (IAEA-368). The results were satisfactory. For sediment samples, overall chemical recoveries varied from 60–90%. The developed method was applied to the study of 241Am depth distribution in Sagami Bay, Japan, where we observed different depth profiles between 241Am activity and 239+240Pu activity.

Simultaneous quantification of 17 trace elements in blood by dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS) equipped with a high-efficiency sample introduction system

A quadrupole inductively coupled plasma mass spectrometer (Q-ICP-MS) equipped with a dynamic reaction cell (DRC) and coupled with a desolvating nebulization system (APEX-IR) was employed to determine 17 elements (Al, As, Ba, Cd, Co, Cr, Li, Mn, Mo, Ni, Pb, Sb, Se, Sn, Sr, V, and Zr) in blood samples. Ammonia (for Al, Cr, Mn, and V) and O 2 (for As and Se) were used as reacting gases. Selection of the best flow rate of the gases and optimization of the quadrupole dynamic bandpass tuning parameter (RP q) were carried out, using digested blood diluted 1 + 9 with deionized water and spiked with 1 μg L −1 of Al, Cr, Mn, V and 5 μg L −1 of As and Se. Detection limits were determined in digested blood using the 3 σ criterion. The desolvating system allowed a sufficient sensitivity to be achieved to determine elements at levels of ng L −1 without detriment of signal stability. The accuracy of the method was tested with the whole blood certified reference material (CRM), certified for Al, As, Cd, Co, Cr, Mn, Mo, Ni, Pb, Sb, Se, and V, and with indicative values for Ba, Li, Sn, Sr, and Zr. The addition calibration approach was chosen for analysis. In order to confirm the DRC data, samples were also analyzed by means of sector field inductively coupled plasma mass spectrometry (SF-ICP-MS), operating in medium ( m/Δ m = 4000) and high ( m/Δ m = 10,000) resolution mode and achieving a good agreement between the two techniques.

Inductively coupled plasma-sector field mass spectrometry with a high-efficiency sample introduction system for the determination of Pu isotopes in settling particles at femtogram levels

An analytical method for the determination of plutonium concentration and its isotope ratio ( 240Pu/ 239Pu) for settling particle samples by inductively coupled plasma mass spectrometry (ICP-MS) is presented. The generally used approach for Pu preconcentration by increasing the amount of samples is not applicable because of the small size of settling particle samples available for the analysis for Pu isotopes. Efforts were made to improve the sensitivity of a sector-field ICP-MS (SF-ICP-MS) and reduce the 238UH + interference for Pu analysis by combining a high-efficiency sample introduction system (APEX-Q). An extremely low detection limit of 0.07 fg Pu was achieved, which allowed the determination of Pu isotope ratio at femtogram levels. The precision and accuracy of 240Pu/ 239Pu isotope ratio analysis were carefully examined with a certified Pu isotope standard (NBS-947) and an ocean sediment reference material (IAEA-368). Simple anion-exchange chromatography for the separation and purification of Pu was combined with the APEX-Q/SF-ICP-MS system to determine Pu isotopes in settling particles collected in the East China Sea continental margin. The obtained results supported a previous observation on the lateral transport of Pu containing particles in this continental margin.