Non-spectral Interferences Research Articles

Characterization of biogenic selenium nanoparticles in hypersaline media by single particle inductively coupled plasma mass spectrometry: Haloferax mediterranei case

BackgroundSingle particle inductively coupled plasma mass spectrometry (spICP-MS) is extensively employed for the characterization of biogenic selenium nanoparticles (SeNPs) produced by mesophilic microorganisms. Nevertheless, because halophilic microorganisms are also well-known to produce SeNPs, further research efforts are required to investigate spICP-MS applicability for characterizing such nanomaterials in hypersaline media. The goal of this work is to develop a methodology for characterizing SeNPs in hypersaline media by spICP-MS. To this end, plasma operating conditions, non-spectral interferences and calibration strategies were investigated. The proposed method was employed to investigate the capabilities of the halophilic archaea Haloferax mediterranei to produce SeNPs. ResultsBy the appropriate selection of experimental conditions, SeNPs can be accurately analyzed in hypersaline media by spICP-MS. Unlike previous works in the literature, no differences in ionic signal were observed between SeNPs and dissolved Se and, hence, there is no need to apply any empirical corrector factor for obtaining accurate particle size distributions. Non-spectral interferences are mitigated by diluting the sample at least 1:103 which allows the use of water standards. Size (30 nm) and particle (7 × 105 particles mL−1) detection limits were low enough to characterize biogenic SeNPs produced by halophilic microorganisms. The use of the optimized methodology reveals that Haloferax mediterranei can produce SeNPs when it is exposed to selenite up to 1 mM, but no formation is produced for selenate exposure. Depending on incubation parameters (selenite concentration and time), the particle median diameter ranged from 80 to 100 nm, whereas particle concentration varied from 0.8 to 1.9 × 1013 particles mL−1. SignificanceThis represents the first methodology for characterizing biogenic SeNPs in hypersaline media by spICP-MS with accuracy and precision using non-matrix matched standards. It opens the opportunity to investigate the capabilities of halophilic microorganisms (e.g., H. mediterranei) to produce Se-based nanomaterials.

Multielemental determination in lubricating oil samples by microwave-induced plasma optical emission spectrometry after extraction induced by emulsion breaking

Extraction induced by emulsion breaking (EIEB) was studied as a strategy for the determination of Al, Cr, Cu, Fe, Mg, Mn, Mo, Ni, and Pb in used lubricating oil via microwave-induced plasma optical emission spectrometry (MIP OES). No spectral or nonspectral interferences were observed in the developed method. These were evaluated as a function of the emission intensity of natural molecular species in the N2 plasma and different atomic and ionic emission lines. The time required for extraction was evaluated, and the best sensitivity for all the elements was obtained at 40 min of contact between the sample and the extraction solution in the presence of the surfactant. Doehlert matrix response surface methodology was employed to study the effects and interactions between the nitric acid (extractor) and surfactant (emulsifier) concentrations during sample preparation. The recommended conditions for 3.0 g of sample were as follows: 5.0 mL of extraction mixture consisting of 2.8 mol/L nitric acid and 3.0 % (v v−1) of the surfactant Triton X-114. The limits of quantification obtained were 2.9 (Al), 43 (Cr), 4.0 (Cu), 17 (Fe), 4.0 (Mg), 3.7 (Mn), 7.0 (Mo), 9.2 (Ni) and 45 (Pb) µg kg−1. The method developed was applied in the analyses of lubricating oil samples. The following concentration ranges (mg kg−1) were found: 2.5–106 (Al), 2.8–24.8 (Cr), 3.5–21.4 (Cu), 16.9–199 (Fe), 33.4–64.0 (Mg), 0.57–9.7 (Mn), 4.7–43 (Mo), 1.6–11.1 (Ni) and 2.0–12.6 (Pb).

A technique for depositing iron, tungsten, molybdenum, and chrome in the determination of selenium and tellurium in alloy steel by ICP-AES method

Direct determination of the content of selenium and tellurium impurities in metallurgical materials by the method of inductively coupled plasma atomic emission spectroscopy (ICP-AES) is difficult due to spectral and non-spectral interference from macrocomponents present in the materials under study. The separation of micro-(Se, Te) and macro-components (Fe, W, Mo, Cr, Cu, Ni, Co) through preliminary precipitation is the goal of the study. The use of barium acetate and sodium fluoride as precipitants are shown to provide an effective separation of Se and Te from Fe, W, Mo, and Cr (the content in the analyzed solution is less than 0.1 wt.% of the original) and partial separation from Cu, Ni, and Co (the content in the analyzed solution from 25 to 55 wt.% of the original). Optimal conditions for the deposition of macrocomponents (Fe, W, Mo, Cr) and inhibition of the process of coprecipitation of selenium and tellurium on sediments of macrocomponents for their subsequent ICP-AES determination were determined. The optimal pH for the precipitation of macrocomponents equals 1. The optimal mass of precipitants (barium acetate and sodium fluoride) is 10 and 3 g, respectively. To inhibit the process of coprecipitation of selenium and tellurium on sediments of macrocomponents, it is proposed to use hydrofluoric acid. The optimal volume of hydrofluoric and hydrochloric acids for inhibiting the process of coprecipitation of analytes on sediments of macrocomponents was determined (3 and 6 cm3, respectively). The developed procedure for separating micro-Se, Te from macro-components was tested on standard samples of alloyed steels using the «spike» method. The technique is characterized by satisfactory accuracy and reproducibility, the limit of determination of analytes after separation of macrocomponents is 10–3 wt.%.

Optimizing the performance of single-cell ICP-MS/MS for Fe and Zn determination in human umbilical vascular endothelial cells

Inductively coupled plasma-mass spectrometry operated in a single-cell mode (scICP-MS/MS) has emerged as a technique that allows measurement of metal concentration at the cellular level. The approach is made possible by the high sensitivity of modern instrumentation. However, specific applications may be limited by spectral and non-spectral interference that can occur due to the complexity of the matrix that requires to be analysed. As such, the success of this approach requires adequate sample preparation, allowing the stability of the cells to be preserved before introducing them into the plasma. In this context, a method was developed to measure Zn and Fe concentrations in individual human umbilical vein endothelial cells (HUVEC) using scICP-MS/MS. As a strategy, the suspension of HUVECs was prefixed with paraformaldehyde aiming to achieve experimental stability and repeatability without significantly affecting the background signal. Moreover, different dwell times (3, 5 and 10 ms) were assessed to optimize the instrumental parameters. As a result, the best performance for Zn and Fe measurement by scICP-MS/MS in terms of sensitivity and accuracy was obtained with the dwell time of 3 ms. To the best of our knowledge, the concentrations of Fe and Zn in fixed single endothelial cells has not been explored previously using scICP-MS. Here, the developed scICP-MS/MS method was successfully used to examine the influence of different culture conditions on Fe and Zn uptake in fixed single HUVEC cells.

Microwave-sustained inductively coupled atmospheric-pressure plasma (MICAP) for the elemental analysis of complex matrix samples

Microwave induced plasma optical emission spectrometry (MIP-OES) has gained widespread attention in the last few years for trace elemental analysis. Among the new generation of MIPs it is worth to mention the microwave-sustained inductively coupled atmospheric-pressure plasma (MICAP) for which previous works have shown similar detection capabilities to those afforded by ICP-OES. Nevertheless, this instrument has not been applied yet to complex matrix sample analysis. Therefore, the goal of this work is to evaluate MICAP-OES performance (e.g., analytical figures of merit, matrix effects, etc.) for elemental analysis of samples of different nature (e.g., environmental, food and polymers). To this end, both spectral and non-spectral interferences were investigated for 19 elements (Ag, Al, As, B, Ca, Cd, Co, Cr, Cu, Fe, Ga, In, Mg, Mn, Ni, Pb, Sr, Tl, Zn) in the presence of inorganic acid, organic and saline solutions and compared to a 5 % w w−1 HNO3 solution. Unlike previous MIPs, experimental data showed that the optimum nebulizer gas flow rate for a given emission wavelength was mostly independent of matrix characteristics. Regarding matrix effects, this device was highly robust operating both inorganic acid and organic matrices. Interestingly, when operating saline matrices, changes on emission signal by easily ionizable elements were less significant than those early reported by alternative MIP cavities. Moreover, due to MICAP spectrometer design employed allows real-time simultaneous analysis, Rh, Pd, Sc and Y were suitable internal standards to minimize non-spectral interferences. Finally, MICAP-OES can be successfully applied to the elemental analysis of different complex matrix samples (i.e., CRM-DW1 Drinking water; BCR-146 Sewage sludge industrial; BCR-185 Bovine liver; BCR-278R Mussel tissue; NIST-1549 Non-fat milk powder; ERM-EC681k Polyethylene (high level) and BCR-483 Sewage sludge amended soil).

EXPERIMENTAL AND THEORETICAL STUDY OF THE BEHAVIOR OF GALLIUM IN A DISCHARGE PLASMA AT ICP-AES DETERMINATION

In the case of inductively coupled plasma atomic emission determination of gallium in metallurgical materials, matrix components can have a significant influence on the determination results. In addition to matrix spectral interference, there may also be non-spectral interference from macrocomponents. The element present in the discharge plasma at high concentrations can lead to a change in the conditions for excitation of the emission spectra, which will lead to a distortion of the intensity of the spectral lines of gallium. It has been established that the spectral lines of gallium are not free from spectral overlap from macrocomponents (iron, chromium, molybdenum, tungsten, nickel and cobalt). As a result, experimental study of non-spectral interference using gallium spectral lines is impossible. Using thermodynamic modeling, a quasi-analyte element was selected, which was proposed to be used to study the non-spectral matrix effect on the analytical signal of gallium during its atomic emission determination with inductively coupled plasma. Indium was proposed as a quasi-analyte. Based on the results of thermodynamic modeling, it was established that when varying the operating parameters of the atomic emission spectrometer (plasma temperature, argon and aerosol flow rate), the spectral behavior of gallium and the proposed indium quasi-analyte in argon plasma is similar. In this case, there is no spectral interference from the quasi-analyte on the spectral lines of gallium, and the increase in the value of the matrix interference estimate observed in some cases is random, which may be due to the time drift of the operating parameters of the atomic emission spectrometer. Thus, it is proposed to use indium as a quasi-analyte for the experimental study of non-spectral interference from matrix components (iron, chromium, molybdenum, tungsten, nickel and cobalt) instead of detectable gallium in metallurgical materials.

Determination of Essential and Non-Essential Elements in Dietary Supplements by Microwave-Induced Plasma Optical Emission Spectrometry: Method Development and Study of Non-Spectral Interferences

Dietary supplements have been used to overcome nutritional deficiencies and the knowledge concerning essential and non-essential elements is an important issue. In this work the suitability of microwave-induced plasma optical emission spectrometry (MIP OES) for the determination of essential and non-essential elements in dietary supplements was evaluated. Twelve dietary supplement samples of several classifications (vitamins/minerals, minerals, amino acids, and botanicals) were digested in their whole form for determination of essential (Ca, Co, Cu, Fe, K, Mg, Mn, Mo, Na, and Zn) and non-essential (Ag, Al, B, Ba, Be, Cd, Cr, La, Li, Ni, Pb, Sr, and V) elements by MIP OES. Potential non-spectral interferences by common concomitants (C, S, K, Na, and Ca) were evaluated, as well as those by residual acidity of digests. The study of non-spectral interferences showed that a signal suppression effect is observed with higher concentrations of Ca, Na, and K. Relatively good robustness was observed considering the presence of C and S, as well as residual HNO3. The limits of quantification (LOQs) were dependent on the sample mass used for decomposition (from 0.6 to 1.6 g in the commercial product) and on the minimum dilution factor. From the results, there was a prevalence of essential and non-essential elements in vitamins and minerals, minerals, and botanicals-based dietary supplements, whereas lower concentrations were found in the dietary supplements based on amino acids. All elements were in a concentration below the recommended dietary allowances (RDAs), exception for those with the concentration intentionally higher. Accuracy of results by MIP OES was evaluated by using standard reference materials (SRM) NIST 1572 and NIST 1575a. In addition, results showed no statistical difference by comparison with those by ICP OES. MIP OES proved to be a suitable technique for the determination of metals in dietary supplements, being a feasible alternative for the quality control of these products.

Exploring single-particle ICP-MS as an important tool for the characterization and quantification of silver nanoparticles in a soybean cell culture

The application of nanomaterials in the plant biotechnology field is widespread for many functions, such as the enhancement of callus induction and sterilizer agents. On the other hand, the use of in vitro plant techniques has provided nanotoxicology information at a cellular level. In this context, the use of emerging analytical techniques, such as single-particle inductively coupled plasma mass spectrometry (spICP-MS), can contribute to the development of this field. This work aims to explore the use of spICP-MS to characterize and quantify silver nanoparticles (40, 60, and 80 nm) in a plant cell medium culture (Murashige and Skoog medium, or MS medium). A preliminary study was carried out to investigate the non-spectral interference caused by the matrix, and signal suppression at a high plant cell medium culture concentration (440 mg L−1) was verified; consequently, the accuracy for the mass-based concentration was found to be below 70%. However, at a low medium concentration (4.4 mg L−1), the recovery found for size, mass, and number-based concentration was higher than 80% for all nanoparticle sizes. A matrix-matching calibration was performed to overcome these interferences, and the accuracy was significantly improved. Examples of the application of spICP-MS, such as the estimation of silver nanoparticle stability in a plant cell liquid medium and silver fractionation in soybean callus samples after in vitro plant culture, were demonstrated. In conclusion, spICP-MS is an interesting and valuable approach in this research field, providing information regarding the interaction of plant cells and nanoparticles.

A sub-ppbv-level Acetone and Ethanol Quantum Cascade Laser Based Photoacoustic Sensor – Characterization and Multi-Component Spectra Recording in Synthetic Breath

Trace gas analysis in breath is challenging due to the vast number of different components. We present a highly sensitive quantum cascade laser based photoacoustic setup for breath analysis. Scanning the range between 8263 and 8270 nm with a spectral resolution of 48 pm, we are able to quantify acetone and ethanol within a typical breath matrix containing water and CO2. We photoacoustically acquired spectra within this region of mid-infra-red light and prove that those spectra do not suffer from non-spectral interferences. The purely additive behavior of a breath sample spectrum was verified by comparing it with the independently acquired single component spectra using Pearson and Spearman correlation coefficients. A previously presented simulation approach is improved and an error attribution study is presented. With a 3σ detection limit of 6.5 ppbv in terms of ethanol and 250 pptv regarding acetone, our system is among the best performing presented so far.

Analysis of urine by MIP-OES: challenges and strategies to correct matrix effects.

This work investigated the potential of microwave-induced plasma optical emission spectrometry (MIP-OES) for urine analysis using a complex matrix containing carbon and high concentrations of easily ionizable elements (EIEs). The goals were to study interferences originating from the urine matrix for 14 analytes with total energies varying from 1.85 to 12.07 eV, along with strategies to correct matrix effects and compare the results with those reported in the literature using inductively coupled plasma optical emission spectrometry (ICP-OES). It was found that the urine matrix caused suppression of the signals for some elements and increased them for others. Therefore, an internal standardization calibration method and three levels of dilution, i.e., 2-, 20-, and 200-fold, were applied as strategies to correct non-spectral interferences. Also, Ga, Ge, Pd, Rh, Sc and Y and four molecular species present in the nitrogen plasma (i.e., CN, N2, N2+, and OH) were investigated as potential internal standards (ISs). The accuracy and precision were evaluated by addition and recovery experiments and best results were obtained using ISs Ge, Rh and Sc for 20-fold dilution and N2+ for 200-fold dilution. The LODs ranged from 0.33 to 329 μg L-1 and deviations were lower than 11%. The combined use of these strategies led to successful urine analysis for a spiked sample by MIP-OES.

Organics non-spectral interferences on nanoparticle characterization by means of single particle inductively coupled plasma mass spectrometry

Organic non-spectral interferences on both number concentration and particle size distribution have been systematically investigated for Au-, Pt and SeNPs.

Unified analysis method for total and inorganic As determination in foodstuffs by hydride generation high-resolution continuum source quartz tube atomic absorption spectrometry.

A unified analytical method applicable to common foodstuff matrices was developed and characterized for total and inorganic arsenic determination by hydride generation high-resolution continuum source quartz tube atomic absorption spectrometry, which was established based on different sample preparation procedures. This new method was found to be interference-free and cost-effective in terms of reagents consumption for sample preparation and derivatization to arsine for the inorganic arsenic fraction. Microwave-assisted digestion in HNO3-H2O2 for total arsenic and extraction in 0.28 mol L-1 HNO3 by mechanical stirring in a water bath or ultrasound-assisted extraction in 0.01 mol L-1 HCl without separation of inorganic As, all coupled with arsine generation in 0.01 mol L-1 HCl medium with 0.6% NaBH4 in 0.01% NaOH in the presence of 0.2% L-cysteine was found to be suitable for all matrices. The results were statistically compared by applying Tukey's and Dunnett's multiple comparison methods (p > 0.05). The use of external calibration with As(III) standards and standard addition method for quantification showed the lack of non-spectral interferences from the multimineral matrices, resulting in a reliable method for total/inorganic As determination in various foodstuffs. The limits of detection for total/inorganic As using peak height measurement were 0.0044 ± 0.0005/0.0022 ± 0.0003 mg kg-1 (n = 25 days). The overall recovery for total/inorganic As in the certified reference materials was in the range of 98% ± 22%, and 99% ± 24% (k = 2). The extraction of inorganic As in 0.01 mol L-1 HCl and 0.28 mol L-1 HNO3 provided the recovery of 106% ± 25% and 100% ± 25% (k = 2), which was better than in 10 mol L-1 HCl. The precision of measurements in real samples of fish muscle, meat and organs, rice and rice-based baby foods with contents of 0.052-5.29 mg kg-1 total As and 0.005-0.063 mg kg-1 inorganic As was 9.8-18.8% and 8.7-32.0%, respectively, which was calculated based on the combined uncertainty.

Determination of bromine and fluorine via sequential vaporization of TlBr and CaF molecules from the same aliquot by high-resolution continuum source graphite furnace molecular absorption spectrometry

This work describes the development of a multielement method for determination of bromine and fluorine, via sequential vaporization of TlBr and CaF molecules, from the same sample aliquot, using high resolution molecular absorption spectrometry. The molecular absorption of TlBr and CaF was measured at 342.9797 nm and 606.4322 nm, respectively. Studies were conducted by injecting 10 μL of sample or standard of bromine and fluorine into the graphite furnace. The source of the molecule-forming agents was 10 μL of solutions at 8.0 g L−1 of thallium and calcium, individually prepared from TlNO3 and Ca(NO3)2·4 H2O. The optimized vaporization temperatures were at 900 °C (TlBr) and 2100 °C (CaF). No chemical modifiers were used, and calibration against aqueous standard was employed. The limits of detection (LOD) were 2 ng (Br) and 0.02 ng (F). The linear ranges were 5–5000 ng (Br) and 0.5–100 ng (F). The evaluation of potentially interfering species showed no interference due to the presence of bromide over the signal for CaF or fluorine over the signal for TlBr. No interference was observed for TlBr with up to 20 μg of chlorine. However, for the CaF molecule, significant depreciation of the signal for 5 ng of fluorine was observed in the presence of 10 μg of chlorine. This interference is visually indicated by the appearance of a structured background, relative to the formation of CaCl, in the region next to CaF absorption. To verify the accuracy and performance of the proposed method, drug samples were analyzed with reported values for bromine or fluorine, sea lettuce reference material BCR 279 with informed value for bromine and road dust sample CW7 with no reported values. The determined values closely agreed with the reference values for the drugs and BCR 279 samples. However, for the road dust sample, non-spectral interference was observed. Nevertheless, the results here are promising and indicate the way to develop similar studies.

Determination of arsenic, cadmium, mercury, lead and nickel as elemental impurities in atorvastatin calcium by inductively coupled mass spectrometer.

Atorvastatin calcium is employed as front-line treatment for cardiovascular diseases. According to the international conference on harmonization (ICH) guideline ICH Q3D, elemental impurities can come into drug products from various sources. These elemental impurities do not have any therapeutic benefit to the end-user. On the contrary, it harms the normal physiological system. Class 1 elements like arsenic, cadmium, mercury, and lead are inorganic impurities that can cause toxic effects on the human body. Nickel was used as a catalyst during the synthesis process of atorvastatin calcium. It comes under the Class-2A, can cause toxicity to humans, and must be quantified. A simple, fast, reliable inductively coupled plasma mass spectrometric method for the estimation of elemental impurities like arsenic, cadmium, mercury, lead, and nickel in atorvastatin calcium by open sample digestion technique was developed and validated in accordance with ICH Q3D and USP < 232 > and USP <233 > general chapter. Internal standards like indium, terbium, thallium, bismuth and yttrium were used to correct the non-spectral interferences that were generated during analysis. Gold was added to all solutions as it preserves mercury by amalgamation. The system performance was evaluated every time my performing system suitability parameters. The limits for all the elements were fixed in accordance with ICH Q3D. The limit of detection and the limit of quantification for all the five elements were estimated. Method specificity was proven by checking for interferences due to the sample matrix and other elements. Linearity of each element in standards was established from 25% to 200% of sample concentration, and correlation coefficients were found to be not less than 0.999. The accuracy of the method was demonstrated at three spiking levels at 50%, 100%, and 150% of the J-value for all the elements. The recoveries for all elements at each level were within the range of 90-120%. Method precision was proved at 100% J-value. The relative standard deviation of all elements was less than 5%. It concludes that this newly developed and validated reliable inductively coupled plasma mass spectrometric method for estimating of elemental impurities like arsenic, cadmium, mercury, lead, and nickel in atorvastatin calcium was within the permitted limit and suitable for routine use.

Smanjivanje matriks efekta u analizi zlata i srebra ICP-MS tehnikom

Inductively coupled plasma mass spectrometry (ICP-MS) has been an indispensable technique in the analysis of geological samples in the last few decades. This technique can determine a large number of trace elements, such as the precious metals and rare earth elements. However, the technique is limited by the spectral and non-spectral interferences, which can affect the results of analysis. The aim of this study was to reduce the non-spectral interferences by the method of sample dilution (1000 - 10000). A sample containing gold-bearing minerals was subjected to a digestion in aqua regia, and determination was performed on a NexION 1000 PerkinElmer ICP-MS instrument. The results showed that the differences in gold and silver concentrations in the standard and He modes were insignificant at a dilution of 10000 indicating that the matrix effect was reduced applying a higher dilution. The results of XRD analysis have showed that the sulphide minerals pyrite (FeS2 ) and covellite (CuS) were very abundant in the tested samples, so the digestion of these samples with aqua regia has yielded the solutions containing iron and copper as the most abundant components of the matrix.

Simultaneous Determination of As, Bi, Sb, Se, Te, Hg, Pb and Sn by Small-Sized Electrothermal Vaporization Capacitively Coupled Plasma Microtorch Optical Emission Spectrometry Using Direct Liquid Microsampling.

The simultaneous determination of chemical vapor-generating elements involving derivatization is difficult even by inductively coupled plasma optical emission spectrometry or mass spectrometry. This study proposes a new direct liquid microsampling method for the simultaneous determination of As, Bi, Se, Te, Hg, Pb, and Sn, using a fully miniaturized set-up based on electrothermal vaporization capacitively coupled plasma microtorch optical emission spectrometry. The method is cost-effective, free from non-spectral interference, and easy to run by avoiding derivatization. The method involves the vaporization of analytes from the 10 µL sample and recording of episodic spectra generated in low-power (15 W) and low-Ar consumption (150 mL min−1) plasma microtorch interfaced with low-resolution microspectrometers. Selective vaporization at 1300 °C ensured the avoidance of non-spectral effects and allowed the use of external calibration. Several spectral lines for each element even in the range 180–210 nm could be selected. Generally, this spectral range is examined with large-scale instrumentation. Even in the absence of derivatization, the obtained detection limits were low (0.02–0.75 mg kg−1) and allowed analysis of environmental samples, such as cave and river sediments. The recovery was in the range of 86–116%, and the accuracy was better than 10%. The method is of general interest and could be implemented on any miniaturized or classical laboratory spectrometric instrumentation.

Strategies to overcome interferences in elemental and isotopic geochemical analysis by quadrupole inductively coupled plasma mass spectrometry: A critical evaluation of the recent developments.

Quadrupole Inductively Coupled Plasma Mass Spectrometry (ICP-MS) instruments were introduced into geochemical and mineral exploration laboratories nearly four decades ago, providing a technique that could meet their longstanding requirement for the precise and accurate determination of several groups of trace elements and isotopes in geological materials such as rocks, minerals, ores, soils, sediments, and natural water samples. Despite its popularity among geochemists, the technique suffered from spectral and non-spectral interferences some of which seriously affected the quality of the data generated. These interferences have also had a significant impact on the ability of ICP-MS systems to achieve low detection limits. Over the last three decades, technical advances such as the development of high-resolution (HR)-ICP-MS, cool plasma, collision/reaction cell technology (CCT), dynamic reaction cell (DRC) technology, collision reaction interface (CRI), kinetic energy discrimination (KED), tandem mass spectrometry (ICP-MS/MS)/triple quadrupole ICP-MS, and multi-quadrupole ICP-MS have been introduced to eliminate/minimize many of these interferences, with each technique having its strengths and limitations. These technologies have extended the range of elements that can be measured accurately not only in geological materials, but also in several other matrices, with lower detection limits than before. In addition, other methods such as internal standardization, isotope-dilution, standard addition and matrix-matching calibrations have contributed to improving the quality of the data. This paper provides a review of these new developments from the geochemical analysis point of view.

Trends towards Effective Analysis of Fluorinated Compounds Using Inductively Coupled Plasma Mass Spectrometry (ICP-MS).

Increased demand for monitoring and identification of novel and unknown fluorinated compounds (FCs) has demonstrated the need of sensitive fluorine-specific detectors for unknown FCs in both biological and environmental matrices. Inductively coupled plasma mass spectrometry (ICP-MS) is a promising technique for analysis of FCs and has been rated as the most powerful tool in analytical chemistry. However, direct determination of fluorine using this technique is challenged by high ionization potential of fluorine together with spectral and nonspectral interferences which affect the quality of results. To enhance the quality of results, several studies have reported modifications of a conventional ICP-MS analysis procedure on sample preparation, introduction, analysis, and instrument optimization. Therefore, the focus of this study is to discuss different ICP-MS optimizations and future trends towards the effective analysis of FCs using ICP-MS.

Determination of organic chlorine in water via AlCl derivatization and detection by high-resolution continuum source graphite furnace molecular absorption spectrometry.

High-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS-GF-MAS) was employed for determining adsorbable organic chlorine (AOCl) in water. Organic chlorine was indirectly quantified by monitoring the molecular absorption of the transient aluminum monochloride molecule (AlCl) around a wavelength of 261.42 nm in a graphite furnace. An aluminum solution was used as the molecular-forming modifier. A zirconium coated graphite furnace, as well as Sr and Ag solutions were applied as modifiers for a maximal enhancement of the absorption signal. The pyrolysis and vaporization temperatures were 600 °C and 2300 °C, respectively. Non-spectral interferences were observed with F, Br, and I at concentrations higher than 6 mg L-1, 50 mg L-1, and 100 mg L-1, respectively. Calibration curves with NaCl, 4-chlorophenol, and trichlorophenol present the same slope and dynamic range, which indicates the chlorine atom specificity of the method. This method was evaluated and validated using synthetic water samples, following the current standard DIN EN ISO 9562:2004 for the determination of the sum parameter adsorbable organic halides (AOX) for water quality. These samples contain 4-chlorophenol as the chlorinated organic standard in an inorganic chloride matrix. Prior to analysis, organic chlorine was extracted from the inorganic matrix via solid-phase extraction with a recovery rate >95%. There were no statistically significant differences observed between measured and known values and for a t-test a confidence level of 95% was achieved. The limits of detection and characteristic mass were found to be 48 and 22 pg, respectively. The calibration curve was linear in the range 0.1-2.5 ng with a correlation coefficient R2 = 0.9986.

Isotope analysis of highly enriched “silicon-28” by high-resolution inductively coupled plasma mass spectrometry using an internal standard

In order to study the isotopic effects in semiconductor materials, single crystals of high chemical and isotopic purity are required. The reliability of the obtained data on the magnitude and the direction of isotopic shifts depends on the accuracy of determining the concentration of all stable isotopes. In the isotopic analysis of enriched “silicon-28” with a high degree of enrichment (&gt; 99.99%), it is necessary to determine the impurities of 29Si and 30Si isotopes at the level of 10-3 ¸ 10-5 at. %. At this concentration level, these isotopes can be considered as impurities. It is difficult to achieve high measurement accuracy with simultaneous registration of the main and “impurity” isotopes in such a wide range of concentrations. The registration of analytical signals of silicon isotopes must be carried out in the solutions with different matrix concentrations. The use of the solutions with the high concentration of the matrix element requires the introduction of corrections for matrix noise and the drift of the instrument sensitivity during the measurement. It is possible to reduce the influence of the irreversible non-spectral interference and sensitivity drift by using the method of internal standardization. The inconsistency of the literature data on the selection criteria for the internal standard required studying the behavior of the signals of the “candidates for the internal standard” for the ELEMENT 2 single-collector high-resolution inductively coupled plasma mass spectrometer on the matrix element concentration and the nature of the solvent, as well as on the solution nebulizing time. Accounting for the irreversible non-spectral matrix noise and instrumental drift in isotopic analysis of enriched “silicon-28” and initial 28SiF4 by inductively coupled plasma mass spectrometry had allowed us to reduce by 3-5 times the random component and by more than an order of magnitude the systematic component of the measurement error in comparison with the external standard method. This made it possible to carry out, with sufficient accuracy, the operational control of the isotopic composition of enriched “silicon-28”, both in the form of silicon tetrafluoride and polycrystalline silicon obtained from it, using a single serial device in the range of isotopic concentrations 0.0001–99.999%.