Online isotope dilution and inductively coupled plasma mass spectrometry: from elemental to species quantification (original) (raw)
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Fresenius Journal of Analytical Chemistry, 1999
During the past decade, inductively coupled plasma mass spectrometry (ICPMS) has evolved from a delicate research tool, intended for the well-trained scientist only, into a more robust and well-established analytical technique for trace and ultra-trace element determination, with a few thousand of instruments used worldwide. Despite this immense success, it should be realized that in its 'standard configuration' -i.e. equipped with a pneumatic nebulizer for sample introduction and with a quadrupole filter -ICPMS also shows a number of important limitations and disadvantages: (i) the occurrence of spectral interferences may hamper accurate trace element determination, (ii) solid samples have to be taken into solution prior to analysis and (iii) no information on the 'chemical form' in which an element appears can be obtained. Self-evidently, efforts have been and still are made to overcome the aforementioned limitations to the largest possible extent. The application of a double focusing sector field mass spectrometer in ICPMS instrumentation offers a higher mass resolution, such that spectral overlap can be avoided to an important extent. Additionally, in a sector field instrument, photons are efficiently eliminated from the ion beam, resulting in very low background intensities, making it also very well-suited for extreme trace analysis. Also the combination of the ICP as an ion source and a quadrupole filter operated in a socalled 'alternate' stability region, an ion trap or a Fourier transform ion cyclotron resonance mass spectrometer allows high(er) mass resolution to be obtained. With modern quadrupole-based instruments, important types of spectral interferences can be avoided by working under 'cool plasma' conditions or by applying a collision cell. The use of electrothermal vaporization (ETV) or especially laser ablation (LA) for sample introduction permits direct analysis of solid samples with sufficient accuracy
Quantitative aspects of inductively coupled plasma mass spectrometry
Philosophical transactions. Series A, Mathematical, physical, and engineering sciences, 2016
Accurate determination of elements in various kinds of samples is essential for many areas, including environmental science, medicine, as well as industry. Inductively coupled plasma mass spectrometry (ICP-MS) is a powerful tool enabling multi-elemental analysis of numerous matrices with high sensitivity and good precision. Various calibration approaches can be used to perform accurate quantitative measurements by ICP-MS. They include the use of pure standards, matrix-matched standards, or relevant certified reference materials, assuring traceability of the reported results. This review critically evaluates the advantages and limitations of different calibration approaches, which are used in quantitative analyses by ICP-MS. Examples of such analyses are provided.This article is part of the themed issue 'Quantitative mass spectrometry'.
Spectrochimica Acta Part B-atomic Spectroscopy, 2010
Since considerable time, isotopic analysis of different elements present in a sample, material or object (such as the 'light' elements H, C, N, O and S and 'heavy' elements, such as Sr and Pb), has been used in provenancing studies, as several factorsdefined by "the environment" or origin of the samplecan lead to measurable differences in their isotopic composition. For the light elements, traditionally, (gas source) isotope ratio mass spectrometry (IR-MS) is used, while for a long period of time, thermal ionization mass spectrometry (TIMS) was considered as the only technique capable of detecting subtle variations in the isotopic composition of the 'heavier' elements. However, since the introduction of the first inductively coupled plasma mass spectrometers (ICP-MS), considerable attention has been devoted to the development of methodologies and strategies to perform isotopic analysis by means of ICP-MS. While the relatively modest isotope ratio precision offered by single-collector ICP-MS may already be fit-for-purpose under some circumstances, especially the introduction of multi-collector ICP-MS instruments, equipped with an array of Faraday detectors instead of a single electron multiplier, has lead to tremendous improvements in the field of isotopic analysis. As a result, MC-ICP-MS can be seen as a very strong competitor of TIMS nowadays, while it even provides information on the small isotopic variations shown by some elements, that are not or hardly accessible by means of TIMS (e.g., elements with a high ionization energy). Owing to these new instrumental developments, the application field of isotopic analysis by means of ICP-MS is continuously growing, also in the field of provenance determination. This paper is intended as a review of the developments in and the recent applications of isotopic analysis by means of ICP-MS in this specific research field.
Applications of Inductively Coupled Plasma Mass Spectrometry to Trace Element Research and Control
The determination of chemical elements in food: …, 2007
Inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS (LA-ICP-MS) have been applied as the most important inorganic mass spectrometric techniques having multielemental capability for the characterization of solid samples in materials science. ICP-MS is used for the sensitive determination of trace and ultratrace elements in digested solutions of solid samples or of process chemicals (ultrapure water, acids and organic solutions) for the semiconductor industry with detection limits down to sub-picogram per liter levels. Whereas ICP-MS on solid samples (e.g. high-purity ceramics) sometimes requires time-consuming sample preparation for its application in materials science, and the risk of contamination is a serious drawback, a fast, direct determination of trace elements in solid materials without any sample preparation by LA-ICP-MS is possible. The detection limits for the direct analysis of solid samples by LA-ICP-MS have been determined for many elements down to the nanogram per gram range. A deterioration of detection limits was observed for elements where interferences with polyatomic ions occur. The inherent interference problem can often be solved by applying a double-focusing sector field mass spectrometer at higher mass resolution or by collision-induced reactions of polyatomic ions with a collision gas using an ICP-MS fitted with collision cell. The main problem of LA-ICP-MS is quantification if no suitable standard reference materials with a similar matrix composition are available. The calibration problem in LA-ICP-MS can be solved using on-line solution-based calibration, and different procedures, such as external calibration and standard addition, have been discussed with respect to their application in materials science. The application of isotope dilution in solution-based calibration for trace metal determination in small amounts of noble metals has been developed as a new calibration strategy. This review discusses new analytical developments and possible applications of ICP-MS and LA-ICP-MS for the quantitative determination of trace elements and in surface analysis for materials science. ᮊ
Elemental fractionation in laser ablation inductively coupled plasma mass spectrometry
Analytical and Bioanalytical Chemistry, 1996
INTRODUCTION Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) is one of the most powerful micro-analytical technique for trace element and isotopic ratio determinations. Combining high spatial resolution with low limits of detection, it has been successfully applied in several fields like earth, natural and material sciences, biology, forensic, chemistry and industry (e.g.
Analytica Chimica Acta, 2001
A flow system using computer controlled devices to implement binary sampling of small volumes of sample and spike solutions was coupled to an inductively coupled plasma-mass spectrometer to perform programmable isotope dilutions. A computer running software in QuickBasic controlled the time-based sampling of sample and spike solution by switching on/off a set of solenoid valves. Mixing was improved by sampling 15 small aliquots of both solutions at a flow-rate of 65 l min −1 through a capillary tubing connected to a micro-concentric nebulizer (MCN). Each aliquot of 6 l containing the sample plus spike was introduced during 4 s. Programming the sample to spike volumetric ratios in each aliquot allowed to perform different isotopic dilutions generated from a single enriched solution. The flow system was calibrated measuring the isotopic ratios of 112 Cd/ 114 Cd by binary sampling of natural abundance Cd solutions as sample and enriched 112 Cd (97 at.%) solution as spike. The programmed and the measured ratios in the range from 6 to 25 presented good correlation (0.997). For routine analysis, using an estimate analyte concentration, and the isotope ratio within the defined range, the software calculates the time delays to introduce the sample and spike volumes. The true and found concentrations for solutions containing from 2.0 to 20.0 g l −1 Cd attained good agreement at the 95% of confidence level. For these solutions the consumption of enriched 112 Cd (97 at.%) ranged from 33 to 168 pg per determination. About 30 isotope dilutions per hour were achieved.
Microchemical Journal, 2014
This article describes the application of on-line isotope dilution mass spectrometry with inductively coupled plasma (OID-ICP-MS) to the field of trace metal analysis (B, Cd, Cr, Fe, Ni, Pb and Zn) in water samples by the certified reference material (CRM) characterization. Drinking, natural and waste water certified reference materials were analyzed. Emphasis is placed on OID-ICP-MS measurements of highest analytical quality and their validation against direct external calibration mass spectrometry with inductively coupled plasma analysis (ICP-MS). Differences in the calibration strategies such as single OID-ICP-MS versus direct external calibration ICP-MS were discussed. In general, it can be stated that OID-ICP-MS offers high accurate and precise results with small measurement uncertainties, when properly applied, compared to external calibration. Thus, OID-ICP-MS proved to be an ideal solution for routine water sample analysis, increasing sample throughput without any previous sample handling and improving the quality and reliability of the analytical results.
Spectrochimica Acta Part B: Atomic Spectroscopy, 1993
Ah&act--The effect of heating the sample aerosol was studied by installing a heated extension (at 4OOT) between the spray chamber and the torch. Both 5-and 2-mm i.d. extensions were characterized in terms of sensitivities and detection limits for aqueous solutions containing Al, V, Cr, Mn, Co, Ni, Zn, Ga, As, MO, Cd, Sb, La and Pb. The best analytical figures of merit were obtained with the 2-mm i.d. extension, which resulted in detection limits being lowered to an average of 30% of those obtained with the traditional (i.e. extension-free) sample introduction system. This improvement was greater than that expected from the concurrent increase (by an average factor of 1.63) in sensitivities (including no change for Zn and Ga, and a degradation for Cd and Pb). The heated extension therefore significantly reduced noise as a result of the pre-evaporation process which decreased the average droplet size entering the plasma. The greatest ~provement in sens~ti~ty was observed for V, MO and La, three elements forming relatively strong oxides; investigations using Ce and Th (which form even stronger oxides) clearly showed that elements prone to oxide formation were experiencing a shift in their optimum nebulizer flow rate toward that used for multielemental analysis. Thus, the heated extension results in multielemental conditions that are optimal for a wider range of elements.
Spectrochimica Acta Part B: Atomic Spectroscopy, 1998
Capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS) and electrospray (ES) or ion spray (IS) mass spectrometry (MS) are recently introduced techniques for elemental speciation. Both techniques have the potential for rapid elemental speciation with low detection limits. Examples of the use of CE-ICP-MS for elemental speciation of positive, neutral and negative species are discussed. Issues in interfacing CE and ICP-MS are considered briefly. The potential advantages and disadvantages of laminar flow in CE-ICP-MS are examined. Potential difficulties in CE-ICP-MS including loss of sample, chemical matrix effects and changes in speciation during separation are discussed. The interpretation of ES or IS-MS spectra and analysis of complex mixtures are considered. Calibration and chemical matrix effects are assessed. Potential pitfalls of interpreting bare metal ion spectra as elemental analysis are discussed. The need for fundamental understanding of the processes that control ES and IS-MS signals is examined. High conductivity samples currently present difficulties for CE-ICP-MS or ES and IS-MS.