Electrothermal Vaporization Research Articles

Rapid and simultaneous detection of cadmium and mercury in foods based on solid sampling integrated electrothermal vaporization technique

This work presents an innovative solid sampling (SS) integrated electrothermal vaporization (ETV) approach for simultaneous determination of Cd and Hg based on differentiated elemental vaporization and transportation behavior characteristics. A miniature N2/H2 generator, only consuming electricity and H2O, was utilized to yield reducing atmosphere for Cd vaporization; MgO filler was modified to absorb matrix interferent and keep Hg and Cd transportation via 1st catalytic pyrolysis furnace (CPF); and a gearing was employed to move 2nd CPF to receive and trap (amalgamation) the vaporized Hg from ETV and then thermo-release them for simultaneous detection. Under optimized conditions, the limits of detection of Cd and Hg reached 0.02–0.04 ng/g using 0.4 g sample size. The linearities (R2) exceeded 0.998 and recoveries were 85.0–111.9%, indicating favorable analysis precision and accuracy within ∼3 min without sample digestion process. The proposed HgCd analyzer is suitable for rapid monitoring food with simplicity, green and safety.

Data Processing Strategies for the Improved Analysis of Solder by Electrothermal Vaporization (ETV) Coupled to ICPOES

Data Processing Strategies for the Improved Analysis of Solder by Electrothermal Vaporization (ETV) Coupled to ICPOES

Potassium release and mitigation by additives in different biomass combustion systems

Deposition formation on heat-exchanging surfaces and corrosion limit the use and efficiency of solid biomass combustion systems. The main influencing factors on these ash-related problems are the potassium content, the form in which the potassium is bound to the fuel matrix, and the temperature in the combustion system. To avoid these deposition problems, choosing the right fuel for a particular combustion system and vice versa is important.In this work, the temperature in fluidized bed, grate firing, and suspension combustion systems is analyzed by using the example of the power plants Altenstadt and Avedøre, as well as a European municipal solid waste incineration plant. Additionally, the temperature-resolved potassium release of ten different biofuels is analyzed in an electrothermal vaporization unit (ETV) connected to an inductively coupled plasma optical emission spectrometer (ICP-OES). The potential of additives to mitigate the potassium release is analyzed by adding kaolin and coal fly ash to miscanthus, torrefied wood, and beechwood.The results show that hardly any potassium is released into the gas phase at the typical temperatures of fluidized bed systems. Most of the potassium release occurs between 1000 °C and 1400 °C, the typical temperature range of grate combustion systems. This shows that reducing the temperature of the fuel on the grate could drastically reduce the potassium release. However, due to the negative effect on the efficiency, other measures, such as using additives for capturing potassium species, are favored. At the temperatures in suspension-fired combustion systems, almost all potassium is released into the gas phase, and additives cannot mitigate the release at these temperatures. Additives can shift the potassium release of miscanthus and torrefied wood while showing no positive effect when mixed with beechwood.All in all, this work enables a quantitative comparison of various biofuels and a rough evaluation of the suitability of a fuel regarding the deposition formation for different combustion systems.

Rapid and sensitive determination of trace Cd in carbonate samples using direct solid sampling electrothermal vaporization atomic absorption spectrometry

The accurate determination of cadmium (Cd) hosted and accumulated in sedimentary carbonate remains challenging due to its low concentration (ng·g−1) and complex matrix. Conventional methods, such as inductively coupled plasma mass spectrometry (ICP-MS) and graphite furnace atomic absorption spectrometry (GF-AAS), which typically rely on liquid sampling and sample digestion, are tedious, labor-intensive and time-consuming. In this study, a rapid and sensitive method for the direct determination of carbonate-hosted Cd was developed based on solid sampling electrothermal atomic absorption spectrometry (SS-ETV-AAS). This method eliminates the need of acid digestion procedure, allowing the entire analysis, including sample preparation, to be completed within 10 min. To minimize the carbonate matrix effect, ethylene diamine tetra acetic acid disodium salt (EDTA-2Na) was proposed as matrix modifier to facilitate the release of Cd, enabling fast and accurate determination of trace Cd in carbonate samples. Under optimized conditions, the Cd detection limits was found to be as low as 0.17 ng·g−1, and repeatability (relative standard deviation, RSD) was better than 8 % (n = 7). The accuracy of the proposed SS-ETV-AAS was verified by analyzing five carbonate certified reference materials (GBW07127, GBW07129, GBW07130, GBW07135 and JDo-1), two soil certified reference materials (GBW07404a, GBW07405), as well as several actual carbonate samples. All these results demonstrate that the proposed SS-ETV-AAS method provides a simple, rapid and sensitive approach for measuring trace Cd in carbonates.

Recent overview of microextraction of metal ions and pharmaceuticals by solidified floating organic drop microextraction techniques

AbstractThis work presents a comprehensive overview of solidified floating organic drop microextraction, with a particular emphasis on its applications in the analysis of heavy metal ions and different pharmaceutical compounds by sample pretreatment, complexation, and their identification by various analytical techniques. Here, we discussed basic principles, procedures, applications of the technique, and effects of different variables like pH, temperature, stirring rate, extraction time, salts addition, extraction solvent and extraction volume, centrifugation speed, and, vortex time on preconcentration. In brief, the review summarises the various modes of solidified floating organic drop microextraction such as dispersive liquid‐liquid microextraction, ultrasound‐assisted, air‐assisted liquid‐liquid microextraction, and vortex‐assisted solidified floating organic drop microextraction. this review covers the methods combined with analytical techniques such as inductively coupled plasma‐optical emission spectrometry, electrothermal atomic absorption spectrometry, flame atomic absorption spectroscopy, graphite furnace atomic absorption spectrometry, electrothermal vaporization inductively coupled plasma mass spectrometry, high‐performance liquid chromatography, and gas chromatography/mass spectrometry. among these, the incorporation of ultrasonic, vortex, and air agitation improves the dispersion mechanism. The coupling of solidified floating organic drop microextraction with other techniques enhances the selectivity and efficiency of the preconcentration procedure. This review provides a potential overview of the fundamental principles, advancements in various modes, influencing factors, and applications of solidified floating organic drop microextraction, showing its potential for advancements in sample preparation and analytical methodologies across various domains.

Simultaneous determination of Cd, Pb, Cu and Zn as total and labile fractions in soil using a small-sized electrothermal vaporization capacitively coupled plasma microtorch optical emission spectrometer after diffusive gradients in thin-film passive accumulation

A sensitive and free interference method for the determination of total and labile fractions of Cd, Pb, Cu and Zn in soil after DGT passive accumulation and detection by optical emission spectrometry with an Ar microplasma was validated.

Temperature resolved release of inorganic compounds from biomass

The release of inorganic compounds during the thermal conversion of solid biomass can cause severe operational problems in thermal power plants. To effectively reduce fine particle emissions and depositions, it is important to understand the release of problematic elements into the gas phase.This study presents a temperature-resolved analysis of the release of potassium, sodium, chlorine, sulfur, phosphorus, calcium, and magnesium from ten biomass samples. Conventional woody biofuels, alternative woody biofuels, and stalk-like biomass are analyzed in an electrothermal vaporization unit (ETV) which is connected directly to an inductively coupled plasma optical emission spectrometer (ICP-OES). The suppression of secondary gas-phase reactions in the given setup enables the isolated observation of each individual species’ release pattern. The results from this experimental setup are compared to a range of release patterns found in the literature, with a particular focus on potassium. For the high heating rates applied in this setup, the potassium release starts at around 700 °C, with the majority being release between 1000 °C and 1400 °C. Since hardly any potassium is released together with chlorine and sulfur, the majority of it is released as KOH or elemental potassium. Overall, this work presents reproducible temperature-resolved release patterns of inorganic elements from various biogenic feedstocks in an inert atmosphere.

Rapid and sensitive determination of Se and heavy metals in foods using electrothermal vaporization inductively coupled plasma mass spectrometry with a novel transportation system.

Rapid, sensitive and simultaneous determination of trace multi-elements in various plant food samples such as grain, oilseed, vegetable and tea is always a challenge thus far. In this work, a rapid determination method for Se, Cd, As and Pb in food samples by inductively coupled plasma mass spectrometry (ICP-MS) using slurry sampling electrothermal vaporization (SS-ETV) was developed. To improve the analytical sensitivity and precision as well as eliminate the memory effect, a gas turbulator line and signal delay device (SDD) were for the first time designed for the graphite furnace (GF) ETV coupled with ICP-MS. The signal acquisition parameters of ICP-MS, ashing and vaporization conditions, and the flow rates of carrier gas and gas turbulator were investigated for Se, Cd, As and Pb in food samples. Under the optimized conditions, the limits of determination (LODs) for Se, Cd, As and Pb were 0.5 ng g-1, 0.3 ng g-1, 0.3 ng g-1 and 0.6 ng g-1, respectively; the limits of quantification (LOQs) for Se, Cd, As and Pb were 1.7 ng g-1, 1.0 ng g-1, 1.0 ng g-1 and 1.9 ng g-1, respectively; linearity (R2) in the range of 1 to 4,000 ng g-1 was >0.999 using the standard addition method. This method was used to analyze 5 CRMs including rice, tea and soybeans, and the concentrations detected by this method were within the range of the certified values. The recoveries of Se, Cd, As and Pb in plant food matrices including grain, oilseed, celery, spinach, carrot and tea samples were 86-118% compared to the microwave digestion ICP-MS method; and the relative standard deviations (RSDs) were 1.2-8.9% for real food sample analysis, proving a good precision and accuracy for the simultaneous determination of multi-elements. The analysis time was less than 3 min, slurry preparation time < 5 min without sample digestion process. The proposed direct slurry sampling ICP-MS method is thus suitable for rapid and sensitive determination of Se, Cd, As and Pb in food samples with advantages such as simplicity, green and safety, as well as with a promising application potential in detecting more elements to protect food safety and human health.

Rapid and Portable Detection of Hg and Cd in Grain Samples Based on Novel Catalytic Pyrolysis Composite Trap Coupled with Miniature Atomic Absorption Spectrometry.

As toxic metals, Hg and Cd are a concern for food safety and human health; their rapid and portable analysis is still a challenge. A portable and rapid Hg-Cd analyzer constructed from a metal-ceramic heater (MCH)-based electrothermal vaporizer (ETV), an on-line catalytic pyrolysis furnace (CPF), a composite Pt/Ni trap, and a homemade miniature atomic absorption spectrometer (AAS) was proposed for grain analysis in this work. To enhance sensitivity, a new folded light path was designed for simultaneous Hg and Cd analysis using charge coupled device (CCD) in AAS. To eliminate the grain matrix interference, a catalytic pyrolysis furnace with aluminum oxide fillers was utilized to couple with a composite Pt/Ni trap. The method limits of detection (LODs) were 1.1 μg/kg and 0.3 μg/kg for Hg and Cd using a 20 mg grain sample, fulfilling the real sample analysis to monitor the grain contamination quickly; linearity R2 > 0.995 was reached only using standard solution calibration, indicating the sample was free of grain matrix interference. The favorable analytical accuracy and precision were validated by analyzing real and certified reference material (CRM) grains with recoveries of 97-103% and 96-111% for Hg and Cd, respectively. The total analysis time was less than 5 min without sample digestion or use of any chemicals, and the instrumental size and power consumption were <14 kg and 270 W, respectively. Compared with other rapid methods, this newly designed Hg-Cd analyzer is proven to be simple, portable, and robust and is, thus, suitable to quickly monitor Hg and Cd contamination in the field to protect grain and food safety.

In-situ Diffusive Gradients in thin-films passive sampling coupled with ex-situ small-sized electrothermal vaporization capacitively coupled plasma microtorch optical emission spectrometry as green and white method for the simultaneous determination of labile species of toxic elements in surface water

This study presents for the first time the coupling between in-situ Diffusive Gradient in Thin-film (DGT) passive sampling technique and ex-situ small-sized instrumentation based on electrothermal vaporization capacitively coupled plasma microtorch optical emission spectrometry (SSETV-μCCP-OES) for the simultaneous determination of Cd, Pb, Cu, Zn and Hg in surface water. Unique features of the DGT-SSETV-μCCP-OES are low power and low Ar consumption for plasma generation (15 W, 150 mL min−1) and significant improvement of the detection limits following DGT passive sampling. The new method was validated in terms of river water analysis in comparison with graphite furnace atomic absorption spectrometry and thermal decomposition atomic absorption spectrometry. Combining the abilities of preconcentration by in-situ Chelex-DGT passive sampling with plasma microtorch equipped with a low resolution microspectrometer provided multielemental simultaneous determination with detection limits of (μg L−1) 0.01 (Cd, Zn and Hg), 0.02 (Cu) and 0.07 (Pb) in water, at least one order of magnitude better than using grab sampling without preconcentration. It was possible the quantification of labile fraction of priority hazardous metals (Cd, Pb) in river water below the instrumental limits of detection (μg L−1) of 0.12 and 0.80 obtained in SSETV-μCCP-OES without DGT sampling. The precision of the method was in the range 15.3–22.4% (combined uncertainty), while the accuracy was 95–103% and trueness of 27–33% (expanded uncertainty, k = 2). The DGT-SSETV-μCCP-OES coupling proved to be an ideal and powerful tool for surface water analysis in compliance with green and white analytical chemistry concepts. The application of the RGB-12 algorithm provided very good red/green (AGREEprep)/blue/white scores (%) of 100/80/98/93, determined primarily by in-situ DGT passive sampling, very good detection limits and cost-effective SSETV-μCCP-OES instrumentation.

Validation of Electrothermal Vaporization for the Analysis of Biomass Samples and Comparison with Other Methods of Analysis

The analysis of the chemical composition of biomass plays an important role in all steps of the life cycle of biomass, especially in thermal conversion processes. Electrothermal vaporization (ETV) coupled with inductively coupled plasma optical emission spectrometry (ICP-OES) is a promising approach for biomass analysis as almost no sample preparation is required, samples can be analysed quickly, and the release of elements from the sample can potentially be quantified with temperature resolution. In this work, the concentration of seven important side and trace elements is determined in beechwood, torrefied wood, wheat straw, miscanthus, and spruce bark. For comparison and validation of the ETV setup, four additional methods of analysis are applied to determine the elemental concentration. Chemical fractionation analysis (CFA) is conducted to investigate the chemical association form. In addition, microwave pressure digestion is carried out with two different acid solutions (HNO3 and HBF4). X-ray fluorescence (XRF) analysis is performed to determine the ash composition of all samples. The spread between most of the results of the different measurement techniques is with less than 20 % well within the expected range for heterogeneous biomass samples. Large deviations, such as the sulphur concentration in the XRF analysis, can be explained by the method used. The ETV results are in very good agreement with the CFA and microwave pressure digestion results. As these methods are well established, ETV analysis has proven to be suitable for the analysis of side and trace elements in biomass.Graphical

Forensic analysis by solid sampling electrothermal vaporization coupled to inductively coupled plasma optical emission spectrometry.

To analyze trace evidence found at crime scenes, non-destructive analysis techniques or analysis techniques requiring minute amounts of sample are preferred. One such technique is solid sampling electrothermal vaporization (ETV) coupled to inductively coupled plasma optical emission spectrometry (ICPOES), which requires only 0.1-5 mg of sample. As a result, it has been utilized in several applications of forensic research. This article discusses the capabilities of ETV-ICPOES among current analytical methods and introduces its value as a tool for the analysis of forensic evidence. The latest advancements of ETV-ICPOES demonstrate the diverse opportunities for the identification, determination, and discrimination of evidence. Methods of ETV-ICPOES for the direct analysis of various physical evidence, including trace evidence, are reviewed. Some methods involve quantification of multiple elements using, commonly, matrix-matched external calibration with certified reference materials. Other methods combine qualitative multi-element analysis, based on the area of each analyte peak produced during the vaporization step of the ETV temperature program, and multivariate analysis using principal component analysis or linear discriminant analysis. In all cases, internal standardization with an argon emission line first compensates for sample loading effects on the plasma. Perspectives for utilizing ETV-ICPOES in future forensic settings are also offered.

Mercury determination in bioresorbable calcium phosphate using a new electrothermal vaporization system coupled to ICP-MS

A new ETV system coupled to ICP-MS was developed to determine Hg at the ultra-trace level in bioresorbable calcium phosphate-based ceramic materials.

Validation and expansion of sex determination method through analysis of human hair using electrothermal vaporization coupled to inductively coupled plasma optical emission spectrometry

Modifying a sex determination method involving multi-elemental hair analysis enabled successful application to dyed hair and hair from close relations.

Boosting water evaporation via continuous formation of a 3D thin film through triple-level super-wicking routes.

Capillary-fed thin-film evaporation via micro/nanoscale structures has attracted increasing attention for its high evaporation flux and pumpless liquid replenishment. However, maximizing thin-film evaporation has been hindered by the intrinsic trade-off between the heat flux and liquid transport. Here, we designed and fabricated nanostructured micro-steam volcanoes on copper surfaces featuring triple-level super-wicking routes to overcome this trade-off and boost water evaporation. The triple-level super-wicking routes enable the continuous formation of a 3D thin film for highly efficient evaporation by continuous self-driven liquid replenishment and extending the thin-film region. The micro-steam volcanoes increased the surface area by 225%, improving the evaporation rate by 141%, with a rapid self-pumping water transport speed up to 80 mm s-1. A remarkable solar-driven water evaporation rate of 3.33 kg m-2 h-1 under one sun vertical incidence was achieved, which is among the highest reported values for metal-based evaporators. When attached to electric-heating plates, the evaporator realized an electrothermal evaporation rate of 12.13 kg m-2 h-1. Moreover, it can also be used for evaporative cooling with enhanced convective heat transfer, reaching a 36.2 °C temperature reduction on a heat source with a heat flux of 6 W cm-2. This study promises a general strategy for designing thin-film evaporators with high efficiencies, low costs, and multi-functional compatibilities.

Professor Valderi Dressler, a great admirer of young Brazilian scientists, kindly granted BrJAC an interview

Valderi Luiz Dressler holds a chemistry degree (1992) and a master’s in chemistry (1994) from the Federal University of Santa Maria (UFSM), RS, Brazil, a PhD in chemistry (1999) from the Federal University of Santa Catarina, SC, Brazil and post-doctorates from Forschungszentrum Julich GmbH, Germany (2007 and 2010). Currently, he is a full professor and coordinator of the industrial chemistry and bachelor's chemistry degree courses at the UFSM. Dr. Dressler’s research activities mainly include trace analysis and environmental chemistry, involving the techniques of atomic absorption spectrometry (AAS), inductively coupled plasma optical emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), flow injection analysis (FIA), electrothermal vaporization (ETV) and laser ablation (LA). Furthermore, he performs chemical speciation analysis studies involving hyphenated techniques such as liquid and gas chromatography coupled to ICP-MS and also FIA systems coupled to AAS.

Novel Platinum-Nickel Composite Trap for Simultaneous and Direct Determination of Mercury and Cadmium in Soil and Its Mechanism Study.

In this work, following a metal-ceramic heater (MCH) as an electrothermal vaporizer (ETV), a novel composite Pt/Ni trap based on platinizing the foamed nickel was first fabricated to trap Hg and Cd simultaneously. So, a solid sampling Hg-Cd analyzer was developed to simultaneously detect trace Hg and Cd in soil samples, mainly consisting of an MCH, a composite Pt/Ni trap, and an atomic fluorescence spectrometer (AFS). This small-size MCH-ETV system only consumes 100 W for the complete vaporization of Hg and Cd in soil matrices. The Pt/Ni trap fulfills the complete trapping of Hg and Cd following the solid sampling MCH-ETV system and then fast releases them by heating. It was proved that trapped and released Hg and Cd by the Pt/Ni trap are atomic species using X-ray photoelectron spectroscopy (XPS) and other approaches; specially, the effective cotrapping of Hg and Cd might be due to forming alloys of Hg + Pt and Cd + Ni on the Pt/Ni trap. Under the optimized conditions, the method detection limits (LODs) of Hg and Cd reached 0.4 μg/kg and 0.04 μg/kg for a 20 mg sample size, the relative standard deviations (RSDs) were within 12% and 8% for soil samples, respectively, and the recoveries ranged from 96% to 105%, indicating favorable analytical sensitivity, precision, and accuracy. The whole analysis time can be controlled within 5 min without the soil digestion process. The proposed Hg-Cd analyzer is thus suitable for rapid detection of Hg and Cd in soil samples with advantages such as simplicity, green, and safety. Further, the proposed solid sampling ETV-composite trap method has a promising application potential in the field and rapid detection for multielements.

Fast and Sensitive Determination of Cadmium and Selenium in Rice by Direct Sampling Electrothermal Vaporization Inductively Coupled Plasma Mass Spectrometry.

In this work, a direct solid sampling device based on modified graphite furnace electrothermal vaporization (GF-ETV) with inductively coupled plasma mass spectrometry (ICP-MS) was established for the simultaneous detection of trace selenium and cadmium in rice samples. A bypass gas was first designed in GF-ETV to improve the device’s analytical sensitivity and precision. The ashing and vaporization conditions, the flow rates of the Ar carrier and the bypass gases of ICP-MS were all investigated. Under the optimized conditions, the limits of detection (LODs) for Se and Cd were 0.5 μg kg−1 and 0.16 μg kg−1, respectively; the relative standard deviations (RSDs) of repeated measurements were within 8% (n = 6). The recoveries of Cd and Se in rice samples were in the range of 89−112% compared with the microwave digestion ICP-MS method, indicating good accuracy and precision for the simultaneous detection of Se and Cd in rice matrix. The whole analysis time is <3 min without the sample digestion process, fulfilling the fast detection of Se and Cd in rice samples to protect food safety.

Preconcentration and Separation of Gold Nanoparticles from Environmental Waters Using Extraction Techniques Followed by Spectrometric Quantification.

The quantification of gold nanoparticles (AuNP) in environmental samples at ultratrace concentrations can be accurately performed by sophisticated and pricey analytical methods. This paper aims to challenge the analytical potential and advantages of cheaper and equally reliable alternatives that couple the well-established extraction procedures with common spectrometric methods. We discuss several combinations of techniques that are suitable for separation/preconcentration and quantification of AuNP in complex and challenging aqueous matrices, such as tap, river, lake, brook, mineral, and sea waters, as well as wastewaters. Cloud point extraction (CPE) has been successfully combined with electrothermal atomic absorption spectrometry (ETAAS), inductively coupled plasma mass spectrometry (ICP-MS), chemiluminescence (CL), and total reflection X-ray fluorescence spectrometry (TXRF). The major advantage of this approach is the ability to quantify AuNP of different sizes and coatings in a sample with a volume in the order of milliliters. Small volumes of sample (5 mL), dispersive solvent (50 µL), and extraction agent (70 µL) were reported also for surfactant-assisted dispersive liquid–liquid microextraction (SA-DLLME) coupled with electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS). The limits of detection (LOD) achieved using different combinations of methods as well as enrichment factors (EF) varied greatly, being 0.004–200 ng L−1 and 8–250, respectively.

Portable and miniature mercury analyzer using direct sampling inbuilt-metal ceramic electrothermal vaporization

In this work, a small-size inbuilt-metal ceramic heater (IMCH) was for the first time utilized as a solid sampling electrothermal vaporizer (ETV), and then a novel direct sampling mercury analyzer coupled with a miniature atomic absorption spectrometer was thereby fabricated for sensitive determination of mercury in soil. The mercury analyzer is mainly composed of an IMCH-ETV, a catalytic pyrolysis furnace (CPF) using Al2O3 particles as a new filler, an atomic absorption spectrometer (AAS) and a miniature air pump for carrier gas; herein, the mostly used gold amalgamation was canceled. The IMCH with 30 W heating fulfills the 100% vaporization of mercury from up to 80 mg soil samples using 0.1 L min−1 air carrier. Under the optimized conditions, the method detection limit (LOD) was 0.4 ng g−1 for a 50 mg sample and the RSD of 11 repeated measurements of GSS-3a soil certified reference material (CRM) was 4%. Furthermore, the measured Hg values in various soil CRMs and real soil samples were within their certified values and consistent with that using the Chinese standard method (solid sampling catalytic pyrolysis AAS with gold amalgamation); and the recoveries were 85–113%, which proved favorable analytical accuracy and precision. This fabricated instrumentation only occupies 5 kg and 200 W power consumption vs. more than 25 kg and 1000 W for the traditional Hg analyzer. Therefore, the proposed IMCH-ETV-AAS method is very suitable for portable and rapid detection of mercury in soil.