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Analytical and Bioanalytical Chemistry (v.386, #1)
R. Cornelis, J. Caruso, H. Crews, and K. Heumann (Eds.): Handbook of Elemental Speciation II: Species in the Environment, Food, Medicine and Occupational Health
by Ryszard Lobinski (pp. 5-6).
Elemental tagging in inorganic mass spectrometric bioanalysis
by J. Bettmer; N. Jakubowski; A. Prange (pp. 7-11).
Laser ablation inductively coupled plasma mass spectrometry for direct analysis of the spatial distribution of trace elements in metallurgical-grade silicon by Jorge Pisonero; Ivana Kroslakova; Detlef Günther; Christopher Latkoczy (pp. 12-20).
The spatial distribution and concentration of impurities in metallurgical-grade silicon (MG-Si) samples (97–99% w/w Si) were investigated by use of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The spatial resolution (120 μm) and low limits of detection (mg kg−1) for quality assurance of such materials were studied in detail. The volume-dependent precision and accuracy of non-matrix-matched calibration for quantification of minor elements, using NIST SRM 610 (silicate standard), indicates that LA-ICP-MS is well suited to rapid process control of such materials. Quantitative results from LA-ICP-MS were compared with previously reported literature data obtained by use of ICP-OES and rf-GD-OES. In particular, the distribution of element impurities and their relationship to their different segregation coefficients in silicon is demonstrated.
Keywords: Metallurgical-grade silicon; Elemental segregation; Quantification; LA-ICP-MS
Ionic (liquid) matrices for matrix-assisted laser desorption/ionization mass spectrometry—applications and perspectives by Andreas Tholey; Elmar Heinzle (pp. 24-37).
A large number of matrix substances have been used for various applications in matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS). The majority of matrices applied in ultraviolet-MALDI MS are crystalline, low molecular weight compounds. A problem encountered with many of these matrices is the formation of hot spots, which lead to inhomogeneous samples, thus leading to increased measurement times and hampering the application of MALDI MS for quantitative purposes. Recently, ionic (liquid) matrices (ILM or IM) have been introduced as a potential alternative to the classical crystalline matrices. ILM are equimolar mixtures of conventional MALDI matrix compounds such as 2,5-dihydroxybenzoic acid (DHB), α-cyano-4-hydroxycinnamic acid (CCA) or sinapinic acid (SA) together with organic bases [e.g., pyridine (Py), tributylamine (TBA) or N,N-dimethylethylenediamine (DMED)]. The present article presents a first overview of this new class of matrices. Characteristic properties of ILM, their influence on mass spectrometric parameters such as sensitivity, resolution and adduct formation and their application in the fields of proteome analysis, the measurement of low molecular weight compounds, the use of MALDI MS for quantitative purposes and in MALDI imaging will be presented. Scopes and limitations for the application of ILM are discussed.
Keywords: Quantitative MALDI MS; Ionic matrices; Ionic liquid matrices; Low molecular weight compounds; MALDI imaging
Validation and qualification: the fitness for purpose of mass spectrometry-based analytical methods and analytical systems by Maria Careri; Alessandro Mangia (pp. 38-45).
The context of validation for mass spectrometry (MS)-based methods is critically analysed. The focus is on the fitness for purpose depending on the task of the method. Information is given on commonly accepted procedures for the implementation and acceptance of analytical methods as ‘confirmatory methods’ according to EU criteria, and strategies for measurement. Attention is paid to the problem of matrix effects in the case of liquid chromatography-mass spectrometry-based procedures, since according to recent guidelines for bioanalytical method validations, there is a need to evaluate matrix effects during development and validation of LC-MS methods “to ensure that precision, selectivity and sensitivity will not be compromised”. Beneficial aspects of the qualification process to ensure the suitability of the MS analytical system are also evaluated and discussed.
Keywords: Analytical methods; Analytical systems; Mass spectrometry; Validation; Qualification
Electrospray mass spectrometry analysis of dendritic branches bearing peripheral fullerene subunits by Haiko Herschbach; Kohei Hosomizu; Uwe Hahn; Emmanuelle Leize; Alain Van Dorsselaer; Hiroshi Imahori; Jean-François Nierengarten (pp. 46-51).
The electrospray mass spectrometric characterization of neutral dendrons with a carboxylic acid function or a t-butyl ester moiety at the central point and up to eight peripheral C60 subunits has been performed and is described in detail. Molecules bearing a carboxylic acid group at the center turned out to be preferentially ionized by deprotonation, whereas those with a t-butyl ester head group were ionized by reduction of the C60 units in the infusion capillary of the electrospray source.
Keywords: Fullerenes; Dendrimers; In situ reduction; Electrospray mass spectrometry
Liquid injection field desorption/ionization of reactive transition metal complexes by Jürgen H. Gross; Norbert Nieth; H. Bernhard Linden; Ulrike Blumbach; Frank J. Richter; Michael E. Tauchert; Rolf Tompers; Peter Hofmann (pp. 52-58).
Liquid injection field desorption/ionization (LIFDI) has been applied to identify transition metal complexes that are highly reactive to air and moisture by mass spectrometry. The complexes of nickel and rhodium were supplied as dilute solutions (∼0.2 mg ml−1) in toluene, tetrahydrofuran or acetonitrile, and were applied onto the field desorption emitter inside the vacuum of the ion source under inert conditions by means of the injection capillary unique to the LIFDI set-up. LIFDI mass spectrometry on a double-focusing magnetic sector instrument provided spectra exhibiting intense molecular ion peaks for the species investigated or signals that could easily be related to the target compound by assuming neutral loss of the weakest-bound ligand. Eventually, byproducts of the synthesis or other components resulting from incomplete reactions or some degree of decomposition were also detected.
Keywords: LIFDI; Field desorption; Mass spectrometry; Desorption/ionization; Transition metal complexes; Ligands
Mass-analyzed threshold ionization spectroscopy of pyrimidine: determining the geometry in the first excited and the ionic ground states by M. Riese; J. Grotemeyer (pp. 59-68).
Vibrational spectra of the pyrimidine cation in the electronic ground state were measured via several intermediate states of the first excited state (00,16a1, 16a2, 16a4, 16b1, 10b1, 6b2, 6a1, 11, 41, 42 and 121) by mass-analyzed threshold ionization spectroscopy. For the first time, several vibrational modes could be assigned in the first excited and the ionic ground states. Anharmonic coupling is shown to occur in the first excited state due to Fermi resonance between the 11 and the 16a4 vibrations. From the results of the measurements and calculations presented here, pyrimidine is predicted to be planar in the first excited and the ionic ground states, and it belongs to the C2V point group.
Keywords: MATI; REMPI; Ionization energy
Combined use of ESI–QqTOF-MS and ESI–QqTOF-MS/MS with mass-spectral library search for qualitative analysis of drugs by Marion Pavlic; Kathrin Libiseller; Herbert Oberacher (pp. 69-82).
The potential of the combined use of ESI–QqTOF-MS and ESI–QqTOF-MS/MS with mass-spectral library search for the identification of therapeutic and illicit drugs has been evaluated. Reserpine was used for standardizing experimental conditions and for characterization of the performance of the applied mass spectrometric system. Experiments revealed that because of the mass accuracy, the stability of calibration, and the reproducibility of fragmentation, the QqTOF mass spectrometer is an appropriate platform for establishment of a tandem-mass-spectral library. Three-hundred and nineteen substances were used as reference samples to build the spectral library. For each reference compound, product-ion spectra were acquired at ten different collision-energy values between 5 eV and 50 eV. For identification of unknown compounds, a library search algorithm was developed. The closeness of matching between a measured product-ion spectrum and a spectrum stored in the library was characterized by a value called “match probability”, which took into account the number of matched fragment ions, the number of fragment ions observed in the two spectra, and the sum of the intensity differences calculated for matching fragments. A large value for the match probability indicated a close match between the measured and the reference spectrum. A unique feature of the library search algorithm—an implemented spectral purification option—enables characterization of multi-contributor fragment-ion spectra. With the aid of this software feature, substances comprising only 1.0% of the total amount of binary mixtures were unequivocally assigned, in addition to the isobaric main contributors. The spectral library was successfully applied to the characterization of 39 forensic casework samples.
Keywords: Mass-spectral library; Electrospray ionization mass spectrometry; Time-of-flight mass spectrometry; “General unknown screening”
Direct molecular haplotyping of multiple polymorphisms within exon 4 of the human catechol-O-methyltransferase gene by liquid chromatography–electrospray ionization time-of-flight mass spectrometry by Herbert Oberacher; Florian Pitterl; Harald Niederstätter; Elisabeth M. Weiss; Edith Stadelmann; Josef Marksteiner; Walther Parson (pp. 83-91).
The applicability of ion-pair reversed-phase high-performance liquid chromatography hyphenated to electrospray ionization time-of-flight mass spectrometry (ICEMS) for the haplotyping of five SNPs (rs769223, rs4818, rs4986871, rs8192488, rs4680) located within exon 4 of the human catechol-O-methyltransferase (COMT, EC 2.1.1.6) gene is demonstrated. Two differently sized products of polymerase chain reaction—a 71-bp amplicon partially covering the sequence of a 124-bp amplicon—were used to determine unequivocally the allelic states of the single nucleotide polymorphisms linked on both chromosomes. The two amplicons were co-loaded onto the chromatographic column and simultaneously analyzed within a single gradient run. Using the described strategy, 101 individuals representing an Austrian population sample were typed. The obtained haplotype frequencies will serve as reference values in future association studies to examine the impact of the COMT gene on neuropsychiatric disorders. Additionally, two newly discovered polymorphic sites within the sequence of the COMT gene are described (a synonymous C>T mutation at the third position of the amino acid codon 99 in the soluble COMT protein or 149 in the membrane-bound COMT protein; a non-synonymous G>A substitution at the second position of the amino acid codon 95 in the soluble COMT protein or 145 in the membrane-bound-COMT protein).
Keywords: Mass spectrometry; Liquid chromatography; Electrospray ionization; COMT; Haplotyping
Technical innovations for the automated identification of gel-separated proteins by MALDI-TOF mass spectrometry by Olaf Jahn; Dörte Hesse; Marina Reinelt; Hartmut D. Kratzin (pp. 92-103).
The combination of gel-based two-dimensional protein separations with protein identification by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) is the workhorse for the large-scale analyses of proteomes. Such high-throughput proteomic approaches require automation of all post-separation steps and the in-gel digest of proteins especially is often the bottleneck in the protein identification workflow. With the objective of reaching the same high performance of manual low-throughput in-gel digest procedures, we have developed a novel stack-type digestion device and implemented it into a commercially available robotic liquid handling system. This modified system is capable of performing in-gel digest, extraction of proteolytic peptides, and subsequent sample preparation for MALDI-MS without any manual intervention, but with a performance at least identical to manual procedures as indicated on the basis of the sequence coverage obtained by peptide mass fingerprinting. For further refinement of the automated protein identification workflow, we have also developed a motor-operated matrix application device to reproducibly obtain homogenous matrix preparation of high quality. This matrix preparation was found to be suitable for the automated acquisition of both peptide mass fingerprint and fragment ion spectra from the same sample spot, a prerequisite for high confidence protein identifications on the basis of peptide mass and sequence information. Due to the implementation of the stack-type digestion device and the motor-operated matrix application device, the entire platform works in a reliable, cost-effective, and sensitive manner, yielding high confidence protein identifications even for samples in the concentration range of as low as 100 fmol protein per gel plug.
Keywords: Proteomics; Automation; In-gel digest; Sample preparation; Matrix; MALDI mass spectrometry
C and N stable isotope variation in urine and milk of cattle depending on the diet by N. Knobbe; J. Vogl; W. Pritzkow; U. Panne; H. Fry; H. M. Lochotzke; A. Preiss-Weigert (pp. 104-108).
The stable carbon and nitrogen isotopic composition of urine and milk samples from cattle under different feeding regimes were analysed over a period of six months. The isotope ratios were measured with isotope ratio mass spectrometry (IRMS). The δ 13C values of milk and urine were dependent on different feeding regimes based on C3 or C4 plants. The δ 13C values are more negative under grass feeding than under maize feeding. The δ 13C values of milk are more negative compared to urine and independent of the feeding regime. Under grass feeding the analysed milk and urine samples are enriched in 13C relative to the feed, whereas under maize feeding the 13C/12C ratio of urine is in the same range and milk is depleted in 13C relative to the diet. The difference between the 15N/14N ratios for the two feeding regimes is less pronounced than the 13C/12C ratios. The δ 15N values in urine require more time to reach the new equilibrium, whereas the milk samples show no significant differences between the two feeding regimes.
Keywords: Stable isotope; Cattle; Urine; Milk; Feeding regime
Spatially resolved ultra-trace analysis of elements combining resonance ionization with a MALDI-TOF spectrometer by Jochen Maul; Ilia Strachnov; Klaus Eberhardt; Sergej Karpuk; Gerd Passler; Norbert Trautmann; Klaus Wendt; Gerhard Huber (pp. 109-118).
A combined setup for spatially resolved mass analysis of trace amounts of elements and macromolecules is presented. Using a MALDI-TOF mass spectrometer, a laser spectroscopic setup for resonant ionization of neutral atoms has been implemented. This allows for an efficient and selective detection of trace elements by means of resonance ionization mass spectrometry (RIMS). The instrumental scheme is described, and methodological developments are presented. In a first application pure, laser desorption/ionization with TOF-MS was used to measure mass distributions of cosmic nanodiamonds. For further applications regarding the spatially resolved ultra-trace analysis of elements in solid samples, an implanted target was used to characterize both laser desorption/ionization and laser desorption/resonance ionization for the detection of trace elements within. A perspective of the setup is given and future investigations are outlined.
Keywords: MALDI-TOF; Proteomics; Laser desorption/ionization; Ultra-trace analysis; Resonance ionization spectroscopy (RIS); Resonance ionization mass spectrometry (RIMS)
Coupling of imaging NEXAFS with secondary ion mass spectrometry for the chemical and isotopic analysis of presolar cosmic grains by Thomas Berg; Jochen Maul; Nicole Erdmann; Pasqual Bernhard; Stefan Schuppler; Peter Nagel; Christa Sudek; Ulrich Ott; Gerd Schönhense (pp. 119-124).
We present first results of the combination of imaging photoemission electron spectroscopy with imaging mass spectrometry. Imaging NEXAFS was combined with TOF-SIMS in order to perform a spatially resolved chemical and isotopic analysis of microscopic grain samples. Imaging NEXAFS was used for the nondestructive lateral characterization of mineral phases prior to isotopically resolved mass analysis by imaging TOF-SIMS. This novel approach was demonstrated by performing a chemical and isotopic analysis of the rare presolar grain fraction present in the Murchison meteorite.
Keywords: NEXAFS; PEEM; TOF-SIMS; Presolar grains; Mineral phases
Application of glow discharge mass spectrometry to multielement ultra-trace determination in ultrahigh-purity copper and iron: a calibration approach achieving quantification and traceability by Ralf Matschat; Joachim Hinrichs; Heinrich Kipphardt (pp. 125-141).
A new approach was developed for quantitative calibration in GD-MS which can afford reliable and metrologically traceable results for many trace elements and was exemplified for pure copper and pure iron. It can be assumed that the technique can be further improved and applied to the analysis of other pure metals. Pressed copper and iron powder samples were used to calibrate the glow discharge mass spectrometry applied to the analysis of pure copper and iron. The new type of glow discharge mass spectrometer—the Element GD (Thermo Electron Corporation)—was used with a Grimm-type discharge cell for flat samples. Two series of powder samples were prepared for each of the copper and iron matrixes. The powders were quantitatively doped with solutions of graduated and defined concentrations of 40 or 20 analytes, respectively. The mass fractions of the analytes in the dried and homogenized metal powder samples ranged from μg/kg levels up to 10 mg/kg levels. A special technique was developed to press the samples and to form mechanically stable pellets with low risk of contamination. Ion beam ratios of analyte ions to matrix ions were used as measurands. The calibration curves were determined and the linear correlation coefficients were calculated for different intervals of the curves. The linear correlation coefficients are very satisfactory for most of the calibration curves, which include the higher segments of mass fractions; however, they are less satisfactory for the lower segments of the calibration curves. Nevertheless, in many cases rather acceptable and rather promising values were achieved even for these lower segments, representing mass fractions of analytes at ultra-trace level. The comparison of the certified values of different reference materials with the measured values based on calibrations with the pressed powder samples led to deviations less than 30% for most of the considered examples.
Keywords: Glow discharge mass spectrometry (GD-MS); High-purity copper; High-purity iron; Doped and pressed metal powder samples; Grimm-type cell; Metrological traceability
Use of SEC–ICP–MS with a collision cell for determining the interaction of chromium with DNA extracted from metal-contaminated soils by Sabrina R. Mueller-Spitz; Anne P. Vonderheide; Jodi R. Shann; Joseph A. Caruso; Brian K. Kinkle (pp. 142-151).
The potential of chromium to bind to DNA isolated directly from soil microbial communities was investigated in this study. An analytical scheme was developed to distinguish between chromium bound to DNA and its fragments or chromium contained elsewhere in an environmental DNA extract. DNA was extracted from chromium-contaminated soils and purified using DNA clean-up resins. Size-exclusion chromatography was employed due to its advantages in the separation and molecular weight approximation of large biomolecules. It was coupled with two on-line detection systems (spectrophotometric and inductively coupled plasma mass spectrometric) to study the binding of chromium to DNA or other components in a DNA extract. A collision cell was pressurized with helium to remove diatomic and polyatomic interferents resulting from the chosen mobile phase. Chromium peaks were observed in both the large and small molecular weight regions of the chromatogram; to further confirm that the environmentally extracted DNA contained Cr, the subsequently purified DNA was examined for total Cr using flow injection ICP–MS to accommodate small sample volumes. DNA samples isolated from the two soils examined contained 0.5–0.7 ppb Cr, indicating that DNA isolated directly from a chromium-contaminated soil has chromium bound to the nucleic acids.
Keywords: Chromium; DNA; SEC–ICP–MS; Collision cell
Determination of 234U/238U isotope ratios in environmental waters by quadrupole ICP-MS after U stripping from alpha-spectrometry counting sources by José Luis Mas; Renli Ma; Cameron McLeod; Jesús González-Labajo; Alan Cox; Paul Watson (pp. 152-160).
The 234U/238U isotope ratio has been widely used as a tracer for geochemical processes in underground aquifers. Quadrupole-based inductively coupled plasma mass spectrometry (ICP-MS) equipped with a high-efficiency nebulizer and a membrane desolvator was employed for the determination of 234U/238U isotope ratios in natural water samples. The instrumental limit of detection for 234U was at the low pg L−1 level with very low sample consumption. Measurement precision (234U/238U) was 3–5% for bottled mineral water with elevated uranium concentration (>1 μg L−1). For the analysis of groundwater samples from the Almonte-Marisma underground aquifer (Huelva, Spain), uranium was stripped from stainless steel planchets that had previously been used as radiometric counting sources for alpha-particle spectrometry. Potential spectral interferences from other metals introduced during the dissolution were investigated. Matrix-matched blank solutions were needed to subtract the background on 234U due to the formation of platinum argides, and to allow for mass bias correction and background correction. The Pt appears to be an impurity present in the stainless steel, either as a minor component by itself or after extraction from the anode and a subsequent uranium electrodeposition. The 234U/238U isotope ratio data were in very good agreement with those of alpha spectrometry, while precision was improved by a factor of up to 10 and counting time was reduced down to ~20 min (10 replicate measurements).
Keywords: Mass spectrometry/ICP-MS; Water; Radiochemical methods; Isotope ratio
Improved voltage transfer coefficients for nonconductive materials in radiofrequency glow discharge optical emission spectrometry by L. Therese; Z. Ghalem; P. Guillot; P. Belenguer (pp. 163-168).
In radiofrequency glow discharge emission spectrometry (RF-GDOES), the excitation voltage used to create the plasma is applied to the back or front end of the sample to be analyzed. In this paper we focus on back-applied voltage systems (a configuration that represents about half of the instruments available on the market), and on applied voltage problems (the power coupling efficiency and materials analysis are beyond the scope of this study). In the RF-GDOES of nonconductive samples, a voltage drop develops inside the material. The voltage transfer coefficient is defined as the ratio between the peak voltage in front of the sample (facing the plasma) and the peak voltage applied to the back of the sample. In this work, we show that it is possible to increase the voltage transfer coefficient by increasing the capacitance of the sample. The capacitance of a given nonconductive material depends on its surface, its thickness and its permittivity. Increasing the voltage transfer coefficient permits higher power deposition in the plasma. This study is based on an electrical equivalent circuit for the discharge device, which takes into account the sample and reactor capacitances as well as the voltage probes used for the measurements. This circuit, when modeled by a commercial electrical circuit simulator, gives the voltage transfer coefficient as a function of the sample capacitance. Different approaches to increasing the sample capacitance and their influence on the voltage transfer coefficient are presented and related to the 750.4 nm argon line intensity, which is correlated to the electron density.
Keywords: Radiofrequency; Glow discharge; Nonconductive materials
Evaluation of a pulsed glow discharge time-of-flight mass spectrometer as a detector for gas chromatography and the influence of the glow discharge source parameters on the information volume in chemical speciation analysis by Daniel Fliegel; Katrin Fuhrer; Marc Gonin; Detlef Günther (pp. 169-179).
The figures of merit of a pulsed glow discharge time-of-flight mass spectrometer (GD-TOFMS) as a detector for gas chromatography (GC) analysis were evaluated. The mass resolution for the GD-TOFMS was determined on FWHM in the high mass range (208Pb+) as high as 5,500. Precision of 400 subsequent analyses was calculated on 63Cu+ to be better than 1% RSD with no significant drift over the time of the analysis. Isotope precision based on the 63Cu+/65Cu+ ratio over 400 analyses was 1.5% RSD. The limits of detection for gaseous analytes (toluene in methanol as solvent) were determined to be as low as several hundred ppb or several hundred pg absolute without using any pre-concentration technique. Furthermore, the different GD source parameters like capillary distance, cathode–anode spacing, and GD source pressure with regards to the accessible elemental, structural, and molecular information were evaluated. It was demonstrated that each of these parameters has severe influence on the ratio of elemental, structural, and parent molecular information in chemical speciation analysis.
Keywords: Pulsed glow discharge time-of-flight mass spectrometry; Gas chromatography; Mass resolution; Signal stability; Isotope ratios; Speciation analysis
Determination of ceruloplasmin in human serum by SEC-ICPMS by Viorica Lopez-Avila; Orr Sharpe; William H. Robinson (pp. 180-187).
This paper describes an analytical method for the determination of ceruloplasmin (Cp) in human serum. The method uses immunoaffinity chromatography and size-exclusion chromatography (SEC) to “purify” the serum sample prior to analysis of 63Cu and 65Cu by inductively-coupled plasma mass spectrometry (ICPMS). By removing the six most abundant proteins from serum with immunoaffinity chromatography and by using SEC to separate Cu bound by Cp from any free Cu that might be present in the serum sample, we demonstrated that SEC-ICPMS can accurately and reproducibly measure Cp in the ERM DA470 reference serum. Cp identification is based on retention time match of the unknown in the serum sample with the Cp external standard and the presence of 63Cu and 65Cu at a ratio of 2.2±0.1. This method was used to analyze a reference serum certified for Cp, 47 serum samples from four different diseases and a set of normal controls. The reference serum and a serum sample from a patient with myocardial infarction, as well as a Cp standard, were also analyzed by electrospray mass spectrometry to confirm the presence of Cp in the SEC fraction known to contain 63Cu.
Keywords: Metalloproteins; Ceruloplasmin; Size-exclusion chromatography; Inductively coupled plasma mass spectrometry
Dual nebulizer sample introduction system for simultaneous determination of volatile elemental hydrides and other elements by Luís R. Gómez; Gracybell D. Márquez; José R. Chirinos (pp. 188-195).
A dual sample introduction system was explored for volatile hydride generation in inductively coupled plasma–optical emission spectrometry (ICP–OES) performed in the radially viewed mode. The system consists of two pneumatic nebulizers connected to the conventional spray chamber of the instrument via a simple adaptor. This configuration permits hydride generation but still allows other elements to be determined by pneumatic nebulization. This work was focused on the optimization of the plasma operating conditions for the determination of As, Hg, Sb and Se and other elements. The excitation conditions of the ICP–OES instrument operated with the dual sample introduction system were also explored. Results showed that the analytical performance of the dual system for the determination of As, Hg, Sb and Se was superior to those of conventional nebulization systems. The dual system also enabled the determination of elements that do not form volatile hydrides, but with less sensitivity than conventional nebulization systems. An evaluation of the plasma robustness showed that the gases generated in the hydride reactions did not significantly affect the plasma discharge. Similar to conventional hydride generation techniques, the analysis was susceptible to nonspectroscopic interferences produced by transition metals. Finally, the applicability of the dual nebulization system to practical ICP–OES studies was demonstrated by determining the trace elements in an oyster tissue standard reference material.
Keywords: Dual nebulization; Hydride generation; Inductively coupled plasma–optical emission spectrometry; Arsenic; Antimony; Mercury; Selenium