Diane Beauchemin

Inductively Coupled Plasma Mass Spectrometry

Introduction 4786 Conferences 4788 Book and Reviews 4788 Sample Preparation 4789 Reviews 4789 Original Approaches 4789 Instrument Development, Characterization, and Optimization 4791 Direct Sample Introduction 4791 Nebulization 4791 Plasma Processes 4792 Plasma Sampling Processes 4792 Ion Detection 4792 Spectroscopic Interferences 4793 Nonspectroscopic Interferences 4794 Isotope Ratios 4795 Reviews 4795 Original Approaches 4795 Isotope Dilution 4797 Hyphenation to Speciation Methods 4797 Reviews 4797 Nonchromatographic Methods 4797 Liquid Chromatography 4797 Gas Chromatography 4799 Capillary Electrophoresis 4800 Hyphenation to Vapor Generation 4800 Hyphenation to Laser Ablation 4801 Reviews 4801 Femtosecond Lasers 4802 Fractionation 4802 Ablation Cells 4803 Aerosol Transport and Processing 4803 Applications 4804 Calibration 4804 Hyphenation to Electrothermal Vaporization 4806 Hyphenation to Particle-Sizing Techniques 4806 Literature Cited 4807

Determination of arsenic species by high-performance liquid chromatography-inductively coupled plasma mass spectrometry

Arsenic(III), AsV, monomethylarsonic acid (MMAA), dimethylarsinic acid (DMAA) and arsenobetaine (AsB) were separated by high-performance liquid chromatography (HPLC) and determined on-line by inductively coupled plasma mass spectrometry (ICP-MS). Two forms of HPLC were used: ion pairing and ion exchange, with absolute detection limits for arsenic ranging between 50 and 300 pg. These detection limits were independent of the arsenic species when peak area was used for quantification. Anion pairing was found generally to be more sensitive to changes in the matrix of the sample injected. Anion exchange was more tolerant because of the higher buffering capacity of the mobile phase. Cation pairing was found suitable for the determination of DMAA and AsB in a biological sample containing high concentrations of salts.

Matrix effects in inductively coupled plasma mass spectrometry: a review.

Fundamental research on non-spectroscopic interferences, also known as matrix effects, in inductively coupled plasma (ICP) mass spectrometry with sample introduction using nebulization is critically and exclusively examined in this review, starting with fundamental processes that may be a source of matrix effects during sample introduction, ion generation in the ICP, ion extraction through the interface, and ion transport through the ion optics to the detector. Various methods for attenuating matrix effects are then reviewed and illustrated with some examples. Instead of exhaustively reviewing the literature, representative references are used to comprehensively describe the main issues, several of which are also common to ICP optical emission spectrometry.

Determination of seven arsenic species in seafood by ion exchange chromatography coupled to inductively coupled plasma-mass spectrometry following microwave assisted extraction: Method validation and occurrence data

The determination of seven arsenic species in seafood was performed using ion exchange chromatography on an IonPac AS7 column with inductively coupled plasma mass spectrometry detection after microwave assisted extraction. The effect of five parameters on arsenic extraction recoveries was evaluated in certified reference materials. The recoveries of total arsenic and of arsenic species with the two best extraction media (100% H(2)O and 80% aqueous MeOH) were generally similar in the five seafood certified reference materials considered. However, because MeOH co-elutes with arsenite, which would result in a positively biased arsenite concentration, the 100% H(2)O extraction conditions were selected for validation of the method. Figures of merit (linearity, LOQs (0.019-0.075 mg As kg(-1)), specificity, trueness (with recoveries between 82% (As(III)) and 104% (As(V) based on spikes or certified concentrations), repeatability (3-14%), and intermediate precision reproducibility (9-16%) of the proposed method were satisfactory for the determination of arsenite, monomethylarsonic acid, dimethylarsinic acid, arsenate, arsenobetaine and arsenocholine in fish and shellfish. The performance criteria for trimethylarsine oxide, however, were less satisfactory. The method was then applied to 65 different seafood samples. Arsenobetaine was the main species in all samples. The percentage of inorganic arsenic varied between 0.4-15.8% in shellfish and 0.5-1.9% at the utmost in fish. The main advantage of this method that uses only H(2)O as an extractant and nitric acid as gradient eluent is its great compatibility with the long-term stability of both IEC separation and ICP-MS detection.

Investigations on mixed-gas plasmas produced by adding nitrogen to the plasma gas in ICP-MS

Abstract Additions of nitrogen were made to the argon plasma gas of an inductively coupled plasma (ICP) used as an ion source in mass spectrometry (MS). The studies were carried out at constant nebulizer gas flow rate and uptake rate (i.e. constant nebulization efficiency), with the percentage of nitrogen in the plasma gas (from 0 to 10%) and the power (from 1.0 to 1.4 kW) as the only variables. For each set of operating conditions, the analytical characteristics were assessed for 56 Fe + , 57 Fe + , 76 Se + and 78 Se + . The best results were obtained at 1.2 kW where, although the sensitivity was reduced by a factor of up to 5 upon addition of nitrogen to the plasma, the stability of the plasma was improved, resulting in similar (Se) or improved (Fe) detection limits, by up to a factor of 4. A study of the effect of a matrix containing up to 0.1 M Na was also carried out (at 1.2 kW) while the percentage of nitrogen in the plasma gas was raised from 0 to 10%. The results show that the non-spectroscopic interference of Na can be reduced. In fact, with 5% nitrogen in the plasma gas, the effect of 0.01 M Na was essentially eliminated. Furthermore, the accuracy and precision of the 57 Fe + / 56 Fe + and 76 Se + / 78 Se + isotopic ratios were found to improve as the amount of nitrogen was increased. For instance, the precision of the mean 57 Fe + / 56 Fe + ratio measured in solutions containing from 0 to 0.1 M Na improved by an order of magnitude with 10% nitrogen in the plasma, and that of 76 Se + / 78 Se + improved by a factor of 4, which is still quite significant, given the high 76 Ar + background in comparison with the relatively low abundance of 76 Se + . Overall, the results suggest that an Ar-N 2 mixed-gas plasma may be a better ion source for MS than an all argon ICP.

Effect of concomitant elements on the distribution of ions in inductively coupled plasma-mass spectroscopy. Part 1. Elemental ions

Abstract The effect of various concomitant elements in ICP-MS was assessed by measuring the distribution of selected singly charged analyte ions (of Al, V, Cr, Mn, Ni, Co, Cu, Zn, As, Mo, Sb, La, Ce, and Pb) as well as doubly charged ions of La and Ce in the plasma. This was accomplished while moving the ICP across and away from the sampling interface. The effect of each different concomitant element was studied individually. This study included concomitant elements that were similar in ionization potential but different in mass (Na, K, Cs and Cl, I) as well as similar in mass but different in ionization potential (K and Cl, Cs and I). A dependence upon both the mass of the matrix element and the mass of the analyte was observed. The suppression seen increased with increasing matrix element mass and decreased with increasing analyte mass. The effect of the mass of the matrix element was the more significant of the two factors. Space-charge effects were found to be significant for matrix elements of much lower mass than has been suggested previously. The age of the sampling interface was also found to have an effect upon the relative observed locations within the plasma of the suppressions and enhancements. Older sampling interfaces resulted in the ‘crossing point’, where an analyte signal in the presence of a matrix element intersects the reference analyte signal, shifting closer to the load coil. This is likely further evidence of space-charge effects. Finally, some evidence was also found for a shift in ion–atom equilibrium through the suppression observed in the presence of 0.02 M Na, an element for which space-charge effects should be negligible.

Determination of trace metals in an open ocean water reference material by inductively coupled plasma mass spectrometry

The remarkable detection power of inductively coupled plasma mass spectrometry (ICP-MS) was demonstrated by the analysis of an open ocean sea water reference material (with the acronym NASS-2). A 50-fold pre-concentration of several trace metals in the sea water was realised by their adsorption on to silica-immobilised 8-hydroxyquinoline, which separates the elements of interest from the bulk of the alkali and alkaline earth elements. The isotope dilution technique was used for the determination of seven elements (Ni, Cu, Zn, Mo, Cd, Pb and U). Accurate results were obtained for all of these elements except for Mo, with concentrations ranging between 0.027 and 11.5 µg l–1.

Use of a continuous leaching method to assess the oral bioaccessibility of trace elements in seafood.

A continuous leaching method, coupled online with inductively coupled plasma mass spectrometry (ICP-MS) was used on seafood samples to assess the maximum bioaccessibility of several trace elements. The method indeed involves continuous leaching of the food sample by artificial saliva and gastric juice, successively, where this exposition of the food to fresh reagent drives the dissolution equilibrium to the right. Leaching with intestinal juice had to be omitted because it resulted in clogging problems. The experimental apparatus includes a mini-column of powdered sample, which is directly connected to the nebulizer of an ICP-MS instrument. The on-line approach allows a quick assessment of the maximum bioaccessibility of elements of interest by monitoring the real-time release of elements by a given reagent. The method was applied to determine the bioaccessibility of four toxic elements (Al, Cd, Hg, and Pb) and of four essential elements (V, Mn, Cu, and Zn) in certified reference materials and in actual seafood samples. In all cases, mass balance was verified by carrying out the total digestion of the remaining residue from the mini-column and the relationship between total concentration and bioaccessibility was examined.

A simple method for the speciation analysis of bio-accessible arsenic in seafood using on-line continuous leaching and ion exchange chromatography coupled to inductively coupled plasma mass spectrometry

A quick and simple on-line leaching method was used to assess the maximum bio-accessibility of As in seafood samples. Artificial saliva, gastric juice and intestinal juice were successively pumped through a mini-column of sample (maintained at 37 °C in a thermostatically controlled water bath), which is connected to the nebulizer of an inductively coupled plasma mass spectrometry (ICP-MS) instrument. In contrast to the usual batch method, this approach allows the continuous monitoring of the progressive release of As by the 3 reagents. Thus, the dissolution equilibrium is driven to the right, thereby enabling the determination of the maximum amount of analyte that can be dissolved (i.e. the worst-case scenario). Results for 4 certified reference materials (CRMs) show that saliva alone was sufficient to release, in less than 5 min, all the bio-accessible total As that was mobilised by saliva and gastric juices in the batch mode. The As speciation in each leachate was then determined by ion-exchange chromatography (IEC) coupled to ICP-MS, after adjustment to the gradient program previously optimised by experimental design, along with a 5-fold sample dilution and increased stabilisation time. Under these optimised conditions, 7 different arsenic species in saliva could be separated within 18 min in a single chromatographic run. In all cases, the sum of bio-accessible and residue As concentrations agreed with the certified value. Bio-accessible speciation results were compared and discussed with those previously reported by different extraction methods in the literature.

Inductively coupled plasma mass spectrometry in hyphenation: a multielemental analysis technique with almost unlimited potential

Abstract Inductively coupled plasma mass spectrometry was designed for the multielemental analysis of aqueous samples. However, its range of application can be widely extended using simple hyphenations to other techniques. In this article, various possibilities are reviewed.