Direct Analysis Of Solid Samples Research Articles

Direct analysis of tellurium solid samples with a two-jet arc plasma using electrothermal vaporization

The combination of two-jet arc plasma optical emission spectrometry (TJP-OES) and electrothermal vaporization (ETV) for sample introduction is proposed for the first time.

Direct Mass Spectrometric Analysis of Solid Coal Samples Using Laser Desorption/Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

The direct analysis of complex organic solid samples, such as coal, still represents a challenge for mass spectrometric researchers. In this work, we present an approach to analyze various carbonac...

Sulfur determination using the SiS diatomic molecule via HR-CS GF MAS and direct analysis of solid samples: A versatile method for different matrices

In this work, a simple and reliable method was proposed for sulfur determination in different matrices using the diatomic molecule SiS via high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS) and direct analysis of solid samples. This investigation was carried out using six sulfur standard solutions, Na2S, Na2SO4, BeSO4, thiourea, l-cysteine and sulfamic acid, and nine certified reference materials (CRMs). All measurements were performed using the SiS analytical line at 282.910 nm with 400 μg Zr as permanent modifier and 20 μg Si in basic media as molecule forming reagent. The optimized pyrolysis and vaporization temperatures were 1200 and 2000 °C, respectively. The investigated sulfur sources presented similar analytical signals and statistically equal Aint values for the SiS molecule. Calibration curves with aqueous sulfur standard solutions were used to achieve the limits of detection (LOD) and quantification (LOQ) and the characteristic mass (m0) of 8.8, 29 ng mg−1 and 9.8 ng, respectively, and to determine sulfur in the CRMs. Considering that the investigated wavelength range contained multiple SiS lines, the LOD (2.5 ng mg−1), LOQ (8.4 ng mg−1), m0 (1.0 ng) and the working range (0.008–2.5 μg) were improved by using ten SiS lines (30 pixels) for the measurements. Despite differences in the CRM matrices, the SiS molecule was successfully employed to determine their sulfur concentrations, which were in agreement with the certified values at a confidence level of 95% through Student or Welch t-tests. Therefore, a simple, versatile and reliable method using the SiS molecule was developed to perform sulfur determination in a great variety of sample matrices via HR-CS GF MAS and direct analysis of solid samples.

Challenges and trends for halogen determination by inductively coupled plasma mass spectrometry: A review.

In this review, works published in the past 25 years for fluorine, chlorine, bromine, and iodine determination in several matrices by inductively coupled plasma mass spectrometry (ICP-MS) were covered. Usually, the determination of halogens has been performed by ICP-MS using a previous sample preparation step or, more recently, by direct analysis of solid or liquid samples. Methods based on combustion, extraction, pyrohydrolysis, sample dilution in organic or aqueous medium, and wet digestion, among others, are discussed. Moreover, the recent applications of methods based on laser ablation (LA) and electrothermal vaporization (ETV) coupled to ICP-MS are discussed. The main challenge for methods using sample preparation has been to obtain a final solution compatible with ICP-MS, as well as to overcome problems related to analyte losses and contamination. Interferences due to the presence of dissolved organic compounds in solution, enhancement or suppression of ionization of analytes, and related matrix effects have been of concern when using ICP-MS. For the determination of halogens by ICP-MS using LA and ETV systems, some limitations related to the difficulty of calibration are pointed out, impairing the widespread use of this approach. A critical view is presented for further halogen determination by ICP-MS, mainly for matrices considered difficult to digest using conventional protocols.

Present-Day Possibilities of High-Resolution Continuous-Source Electrothermal Atomic Absorption Spectrometry

The review covers modern directions of the implementation of high-resolution continuous-source electrothermal atomic absorption spectrometry (HR CS ETAAS) for quantitative analysis. Approaches to the direct analysis of solid samples of various compositions, including determination using aqueous reference solutions, analysis of suspensions and sorbates after sorption separation, use of various modifiers, and optimization of the program of heating graphite furnace are systematized. Restrictions of HR CS ETAAS in the determination of poorly volatile elements are noted, methods for increasing the rate of their atomization in a graphite furnace are described. The potentials of HR CS ETAAS for the simultaneous and consecutive monitoring of atomic lines are investigated. The difference between the simultaneous multielement determination and consecutive determination in one aliquot portion is noted. Restrictions of simultaneous multielement analysis by HR CS ETAAS in the number of elements, their thermochemical properties, and intensities of corresponding absorption lines are described. Possibilities of molecular absorption spectrometry for the determination of analytes whose atomic absorption lines are outside the continuous spectrum range of 190–900 nm are discussed. A promising approach to the determination of sulfur, phosphorus, halogens, and aluminum by absorption lines of diatomic molecules is presented.

Applicability of X-ray fluorescence spectrometry for assessing geochemical features and heavy metal contamination of soils: primary data

ABSTRACT X-ray fluorescence spectrometry (XRF) has long been considered a convenient and powerful method for the determination of trace amounts of chemical elements in various types of natural materials. XRF is rapid, reliable, and non-destructive spectroscopic technique, allows performing a direct analysis of solid samples without pretreatment. For the present report, we take advantage of the multielemental capability of the XRF-technique for the determination of major and trace amounts of rock-forming (Stot, Na2O, MgO, Al2O3, SiO2, P2O5, K2O, CaO, TiO2, MnO, Fe2O3(tot)) and trace (F, V, Cr, Co, Ni, Cu, Zn, Ga, Pb, Rb, Sr, Y, Zr, Nb, Ba, La, Ce, Nd) elements in environmental solid samples. Nowadays, study of the soil cover exposed by human-caused impact is an important aspect in understanding the geochemical processes occurring in it. Study object is the biggest territory of the Baikal region named Olkhon, which is a natural area of preferential protection of federal significance and a part of the Baikal National Park. In this study, we have determined chemical composition of the soil upper horizon (~0–15 cm) of meadow-stepper landscapes of the Baikal region (the Olkhon Island) to reveal their geochemical features and heavy metal pollution level. Three varieties of the steppe soils were distinguished: middle loamy, light loamy and sandy loam. For the first time, the influence of soil granulometric features on the content level of the rock-forming and toxic elements in them has been established. In addition, the primary data relating to the assessment of the soil heavy metal contamination have been presented.

Laser-induced breakdown spectroscopy (LIBS) and wavelength dispersive X-ray fluorescence (WDXRF) data fusion to predict the concentration of K, Mg and P in bean seed samples

The present study aims to develop a fast and simple method for the determination of potassium (K), magnesium (Mg) and phosphor (P) in bean seed samples employing a data fusion strategy in the low-level with laser-induced breakdown spectroscopy (LIBS) and wavelength dispersive X-ray fluorescence (WDXRF) techniques combined with direct solid sample analysis. Univariate and multivariate (multiple linear regression, MLR) calibration and leave-one-out cross validation strategies were evaluated to build the calibration models correlated with reference values obtained by inductively coupled plasma optical emission spectrometry (ICP OES) after microwave-assisted acid digestion. The proposed calibration models for WDXRF and LIBS were tested using 14 samples, where the best results were obtained using the data fusion of both techniques. The standard error of cross validation (SECV) obtained were: 0.12% for K, 0.019% for Mg and 0.10% for P, and the trueness ranged between 89 and 124% for K, 82 to 125% for Mg and 73 to 128% for P. These values showed a good accuracy, precise and robustness of the method and a greater reliability of the results. In addition, the predicted concentrations ranged from 0.97 to 1.55% for K, 0.14 to 0.28% for Mg, and 0.27 to 0.82% for P.

Direct Solid Sample Analysis of Medicinal Herbs for Determination of Ba, Cu, Ni, V and Zn by EDXRF

In this work, an analytical method for determination of Ba, Cu, Ni, V, and Zn, in medicinal herbs, through direct solid sample analysis by energy dispersive X-ray fluorescence spectrometry (EDXRF), was applied. Accuracy and precision (intra and inter day) of the analytical method were confirmed through analysis of certified reference material, tomato leaves (CRM NIST 1573a). Principal component analysis (PCA) and hierarchical cluster analysis (HCA) allowed to observe the formation of two groups. Group I was composed by highest levels of Cu and Zn, and the group II with highest concentrations of Ba, V, and Zn. Group I also was subdivided into two subgroups. The concentration of Ni in some samples exceeded the maximum allowed limit. In all samples, Cu and Zn concentration were below the maximum limit allowed by Brazilian legislation. However, for Ba and V, the evaluation was not possible, because there are no maximum limits in legislation.

Solid sampling: advantages and challenges for chemical element determination—a critical review

In recent decades, direct solid sample analysis has been reported in the literature as an alternative to traditional methods of sample preparation, becoming well established in the atomic spectrometry field.

Towards direct analysis of solid and liquid samples exploiting a 3D printed dialysis unit and sequential injection: Application for automated derivatization and determination of gamma-aminobutyric acid in foodstuff and beverages

In this work, a new design of a dialysis unit for direct analysis of solid and liquid samples is presented. The homemade unit was constructed using a 3D printer due to its simple and fast fabrication ability. The dialysis unit is composed of cylindrical-shaped donor and acceptor chambers. A stainless steel sieve is installed inside the donor chamber. SEM images clearly showed that the sieve prevented membrane blockage by suspension particles in the sample. Multiple dialysis units were connected to a sequential injection (SI) system for serial determination of gamma-aminobutyric acid (GABA) in solid and liquid samples. The dialysate from each dialysis unit was consecutively aspirated into the SI flow line for on-line derivatization of GABA with 2-hydroxy-1-naphthaldehyde (3.0% w/v). The derivative was detected spectrophotometrically at 425 nm. The linear calibration range extended to 1000 mg L−1 GABA (r2 > 0.99) with high precision (1.2 %RSD). The developed system was applied to analysis of dietary supplements, grains of germinated brown rice and milk. The samples were directly introduced into the donor chamber either as powder or liquids. The measured GABA content using the developed method was compared using high performance liquid chromatography, with good agreement using Pearson’s correlation (r2 = 0.9999). The method has high accuracy based on recovery studies (99.8 ± 1.5%) and high sample throughput (64 samples h−1).

Elemental Analysis of Aging Effects in Lithium Ion Batteries By Means of Laser Ablation-Inductively Coupled Mass Spectrometry

As the performance of the lithium ion battery (LIB) technology is rising constantly, one of the major challenge remains in the form complex aging phenomena, affecting crucial properties such as cycle life, capacity fade and safety.1 In order to improve the electrochemical performance of LIBs, by preventing or reducing aging effects, a deeper understanding of the degradation of battery materials and factors influencing these processes is needed. Spatial and depth resolved elemental information allows for the study of different processes, such as transition metal dissolution (TMD) and subsequent deposition on the anode surface, as well as loss of active lithium (e.g. through deposition in the solid electrolyte interface (SEI), lithium plating).2 Established techniques for these investigations include time of flight-secondary ion mass spectrometry (ToF-SIMS) and Glow discharge-optical emission spectroscopy (GD-OES). However, small spot sizes, prolonged measurement times or the inability to provide spatial resolved information limit the applicability of these techniques. Laser ablation-inductively coupled mass spectrometry (LA-ICP-MS) offers the unique combination of spatial and depth resolved information, excellent limits of detection, fast measurement times (even for large samples) and easy sample preparation. Therefore this work deals with the application of LA-ICP-MS as a direct solid sample analysis technique for the investigation of the degradation of LIB electrode materials. Mapping experiments are carried out to visualize deposition patterns of lithium and transition metals as well as study factors influencing these depositions. (1) Vetter, J.; Novák, P.; Wagner, M. R.; Veit, C.; Möller, K. C.; Besenhard, J. O.; Winter, M.; Wohlfahrt-Mehrens, M.; Vogler, C.; Hammouche, A. Ageing Mechanisms in Lithium-Ion Batteries. J. Power Sources 2005, 147 (1–2), 269–281. (2) Schwieters, T.; Evertz, M.; Fengler, A.; Börner, M.; Dagger, T.; Stenzel, Y.; Harte, P.; Winter, M.; Nowak, S. Visualizing Elemental Deposition Patterns on Carbonaceous Anodes from Lithium Ion Batteries: A Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry Study on Factors Influencing the Deposition of Lithium, Nickel, Manganese and Cobalt after Dissoluti. J. Power Sources 2018, 380 (January), 194–201.

Differentiation of clay-based pigments in paintings by means of laser ablation-inductively coupled plasma-mass spectrometry

The method of the laser ablation-inductively coupled plasma-mass spectrometry has become an effective tool in the analysis of the art and archaeological objects. With a few exceptions, however, it has not been fully established in the provenance analysis of historical paintings yet. Although the method is micro-destructive for the paint samples, the direct solid sample analysis with just a minor material removal enables obtaining valuable information on the trace element composition, which is useful for the track the origin of mineral pigments, as, e.g. the clay-based pigments. This work aimed for the optimization of the measurement parameters and a subsequent differentiation of red clays from three reference localities in Europe that were pre-selected based on their relevance for the 18th century painting. Finally, the ground preparatory layer from a painting by an 18th century painter, J. G. de Hamilton, has been analysed. It was satisfactorily proved that the red clay used in the ground was mined out in Troschenreuth, Bavaria, Germany. This is in line with the historical documents recording that Hamilton, when he was acting in Bohemia, bought already primed (ready-to-use) canvases in Bavaria. Despite the heterogeneity and small sizes of paint samples the obtained results show the way in which the provenance analysis of clays in paint samples can be performed. This opens up an entirely new possibility of assessing the regional provenance of historical paintings.

An online field-assisted micro-solid-phase extraction device coupled with high-performance liquid chromatography for the direct analysis of solid samples.

Herein, a total online device based on field-assisted extraction (FAE), micro-solid-phase extraction (μ-SPE), and high-performance liquid chromatography (HPLC) was designed. Solid samples were pretreated with ultrasound-microwave synergic effects, and then the extract was cleaned up online with a monolithic column, followed by HPLC analysis. The cross-actions between ultrasound and microwave along with other extraction parameters were studied systematically. The efficiency of this online method was verified in the determination of polycyclic aromatic hydrocarbons (PAHs) in foods and tetracycline antibiotics (TCAs) in cosmetic samples. The detection limits of nine PAHs including fluorene, phenanthrene, anthracene, fluoranthene, benzo[k]fluoranthene, benz[a]anthracene, benzo[b]fluoranthene, pyrene, and benzo[a]pyrene were all within 0.075-0.30μg/kg, as well as four TCAs including oxytetracycline, tetracycline, chlortetracycline, and doxycycline were within 0.02-0.06μg/kg. Six PAHs were found in roast potatoes and baked fish and the recoveries were in the range of 71.5-119.7% with RSDs of 0.2-10.9% (n = 3). The recoveries for TCAs in cosmetic samples were in the range of 75.3-118.0% with RSDs lower than 8.2% (n = 3). Compared with those offline methods, this total online FAE-μ-SPE-HPLC method not only simplifies the operation process, but also increases the precision and accuracy. Beyond trace analytes analysis in solid and semi-solid matrixes, application of this total online analysis method can also be extended to investigate field-assisted extraction mechanisms. Graphical abstract.

Sensitive elemental analysis with high repetition rate laser-ablation spark-induced breakdown spectroscopy combined with lock-in signal detection

High repetition rate laser-ablation spark-induced breakdown spectroscopy (HRR LA-SIBS) combined with lock-in signal detection was developed to realize sensitive trace elements analysis. In order to realize the lock-in signal detection, the repetition rate of laser pulses was increased to 4 kHz and the time duration of the plasma emission was prolonged to be about 10 microseconds by the spark discharge, thus the duty cycle has been increased to 4% approximately. The influence of the continuum background of the plasma emission to the signal detection was reduced with a gated preamplifier. Trace lead and aluminum in brass samples and trace chromium and manganese in aluminum alloy samples were analyzed experimentally. The detection limits of them were estimated to be about 112, 178, 235 and 202 ppb under current experimental condition, demonstrating an obvious improvement on the analytical sensitivity of this technique comparing with conventional single pulse laser-induced breakdown spectroscopy. The HRR LA-SIBS technique combined with lock-in signal detection can be potentially applied to realize direct and sensitive elemental analysis of different solid samples.

Sizing silver nanoparticles in chicken meat using direct slurry sampling graphite furnace atomic absorption spectrometry.

Recently, graphite furnace atomic absorption spectrometry (GFAAS) has been suggested as a tool for detection and sizing of metal nanoparticles (NPs) providing several advantages, such as direct analysis of solid samples, high sample throughput, and robust and cost-efficient instrumentation. For this purpose, evaluation of newly introduced criteria of the absorbance signal, namely, atomization delay (tad) and atomization rate (kat), is performed. However, in real samples, NPs are typically stabilized by either engineered coating reagents or natural materials and occur in unknown concentration. Hence, systematic investigation of possible influences of nine different coating reagents and of Ag concentration on the atomization behavior of silver nanoparticles (AgNPs) was studied. Evaluation of absorption signal characteristics revealed no influence of the coating or Ag concentration on the observed parameters. Furthermore, size-dependent measurements gave reproducible size correlation independent from the coating. Validity of sizing AgNPs with the proposed approach was successfully proven by investigation of two reference materials. The found size of 74.3 ± 5.9nm in RM 8017 (NIST) agrees very well with the certified size of 74.6 ± 3.8nm. Moreover, AgNP size of 25.1 ± 2.5nm found by direct slurry sampling GFAAS in matrix reference material "NanoLyse13"-chicken meat homogenate spiked with PVP-AgNPs-was in very good agreement with the reference value of 27.3 ± 5.3nm as determined by TEM.

Chemometric methods for classification of clonal varieties of green coffee using Raman spectroscopy and direct sample analysis

This work presents the development of methods for classification of clonal varieties of coffee using chemometrics coupled to Raman spectroscopy and direct sample analysis. Spectra were collected directly from each bean in triplicate, and the homogeneity of the sample’s surface was studied. The spectral range between 1200 and 1800 cm−1 is related to organic groups that are relevant for the discrimination of coffee. The main peaks were observed at about 1600 cm−1, 1630 cm−1, 1120 cm−1, and 1200 cm−1. All collected spectra were baseline-aligned, then the preprocessing mean centering (MC) or multiplicative scatter correction (MSC) were used. The original data matrix X was replaced by the PCA-scores matrix T before applying the classification methods. Linear discriminant analysis (LDA), mixture discriminant analysis (MDA), quadratic discriminant analysis (QDA), regularized discriminant analysis (RDA), partial least squares-discriminant analysis with Bayesian inference (PLS–DA), and soft independent modeling of class analogies (SIMCA) methods were applied and compared.Multiplicative scatter correction provided more accurate results when compared to MC, which may be attributed to the direct analysis of solid samples that requires correction for radiation scattering. Using MSC, the LDA correctly classified 98.7% of the samples, while MDA, RDA, QDA, PLS–DA, and SIMCA corrected classified 100% of the samples. On the other hand, using MC, correct classification of the samples was 62.7% for LDA, 70.7% for MDA, 62.7% for RDA, 62.7% for QDA, 61.3% for PLS–DA, and 97.3% for SIMCA.

Simultaneous determination of iron and nickel as contaminants in multimineral and multivitamin supplements by solid sampling HR-CS GF AAS

A methodology to assay simultaneously iron and nickel present as contaminants in multimineral and multivitamin supplements was investigated. High-resolution continuum source graphite furnace atomic absorption spectrometry and direct solid sample analysis were used. Measurements were done with the secondary lines of Fe (352.604 nm) and Ni (352.454 nm) to avoid spectral interferences. The best temperatures for pyrolysis and atomization for Fe and Ni were 1000 and 2700 °C, respectively. Chemical modifiers were not necessary and no matrix effects were observed. Aqueous standard solutions were used for calibration. The limit of detection was 0.517 µg g−1 for Fe and 0.011 µg g−1 for Ni. The precision ranged from 4.3% to 17% and 4.4–20% for Fe and Ni, respectively. The method accuracy was confirmed by comparing statistically the results obtained by solid sampling with those of sample acid digestion. The proposed methodology was successfully applied to determine both metals in different multimineral and multivitamin supplements.

New Spectral Complexes Based on MAES Analyzers

A review of spectral complexes produced by the company VMK-Optoelektronika for atomic emission spectral analysis is presented: Grand-Globula, Grand-Kristall, and Ekspress for the direct atomic emission spectral analysis of solid metal and powder samples; Grand-Potok for the express analysis of powders by a spill–injection technique; Grand-Ekspert and Favorit for the express analysis of metals and alloys; a facility for spark sampling Aspekt for the analysis of metal samples with the help of ICP-AES and ICP-MS; Ekspress-Oil for the direct analysis of oils; and Pavlin for the express determination of sodium, lithium, potassium, calcium, barium, cesium, and rubidium in solutions. The composition and technical characteristics of the spectrometers are reported.

Development of an electrothermal vaporizer for direct mercury determination in soil by inductively-coupled plasma mass spectrometry

The need to determine mercury in environmental samples is well known, along with its related difficulty. Most methods require samples to be decomposed, involving the use of concentrated acids; this requires considerable time and is liable to lead to analyte loss. The aim of this work is to develop a simple electrothermal vaporization (ETV) system coupled to inductively coupled plasma mass spectrometry (ICP-MS) for Hg determination by direct solid sample analysis (DSSA). The ETV system consists of a high-power lamp enclosed in glass chamber equipped with solenoid valves to control the flow of argon gas (Ar) during pyrolysis and vaporization steps. The system is controlled by a printed circuit board and software developed in the LabVIEW environment. In this system, the analyte vapour was extracted through a glass tube positioned just above the sample, avoiding the analyte deposition on the chamber wall and consequently reducing memory effect. The heating program was optimised and the pyrolysis step was not necessary since it was possible to vaporize the analyte at relatively low temperature (700 °C) without matrix interference. Soil mass between 0.500 and 5.000 mg can be analysed with the ETV system. Calibration was carried out by using a certified reference material (CRM) of soil (NIST2709) ranged from 0.1 to 1.0 ng of Hg. The relative standard deviation was lower than 20% (n = 3) and the limit of quantification (10σ) of Hg was 3.1 ng g−1. The accuracy was evaluated by comparison of results obtained for Hg in CRMs and no statistical differences were observed (paired t-test at a confidence level of 95%). To evaluate the performance of ETV system, soil samples with different concentration levels were analysed and the results were in good agreement (paired t-test at a confidence level of 95%) with those obtained by nebulization-ICP-MS (NEB-ICP-MS) after acid extraction. Therefore, the proposed method can be used for routine analysis, where the time of analysis of approximately 60 s per sample, risk of contamination, analyte losses and generation of residues are drastically reduced in comparison with techniques that require sample extraction for Hg determination by NEB-ICP-MS.

Determination of arsenic in agricultural soil samples using High-resolution continuum source graphite furnace atomic absorption spectrometry and direct solid sample analysis

Soils around coal-fired thermal power plants based on coal combustion can present high concentrations of arsenic. This fact has a direct effect on the food chain. Arsenic can be absorbed by plants and vegetables through the soil, which will then serve as food for different animals, spreading the contamination. A method has been developed using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS) for direct determination of arsenic in solid soil samples. Different chemical modifiers were tested to suppress the matrix effects observed. Among them, the modifier that showed the best results was the Zr, used as a permanent modifier. The optimized pyrolysis and atomization temperatures were 1000 °C and 2200 °C, respectively. A calibration curve was established using aqueous standard solutions which was linear up to 16 ng of arsenic. The characteristic mass and limit of detection were 22 pg and 73 pg As, respectively. The accuracy of the method was verified using two certified reference materials and comparison with results obtained for samples after microwave-assisted digestion. Eleven soil samples were collected around the power plant Complex Jorge Lacerda–Tractebel Suezin, in the south of Santa Catarina, Brazil. The concentration of As ranged from 3.4 mg kg−1 to 9.7 mg kg−1, which is within the limits allowed by Brazilian legislation.