Microwave-induced Plasma Atomic Emission Spectrometry Research Articles

Evaluation of in vitro bioaccessibility of Cu, Fe, Mn, and Zn from cooked Uruguayan pink shrimp by microwave induced plasma atomic emission spectrometry

Microwave induced plasma atomic emission spectrometry (MP-AES) was evaluated as a strategy for the analysis of simulated gastrointestinal solutions to estimate the in vitro bioaccessibility of essential elements in cooked pink shrimp. Operational conditions such as pump speed, nitrogen flow, and viewing position were thoroughly optimized for each element. Afterwards the validation of the analytical method was performed. Limits of quantification ranged from 0.005 mg kg−1 (Mn) to 0.106 mg kg−1 (Zn). Accuracy was evaluated by using a certified reference material and performing a mass-balance study. Suitable mass balances within the range 95–105% were obtained. In vitro bioaccessibility in cooked shrimp samples ranged from 14.7% (Fe) to 48.1% (Zn), in agreement with previous data from other shrimp species. The proposed procedure proved to be an outstanding sequential analytical strategy for elemental bioaccessibility studies, providing simplicity and high sample throughput compared to conventional approaches. Furthermore, this work constitutes the first work regarding the optimization of an elemental bioaccessibility study on animal protein employing MP-AES.

A simple method for the determination of toxicologically relevant arsenic species in urine by hydride generation microwave-induced plasma optical emission spectrometry for health risk assessment

This analytical note presents a simple and economic analytical method for quantifying toxicologically relevant arsenic species in urine—the sum of As (III), As (V), monomethylarsonic acid, and dimethylarsinic acid—by hydride generation microwave-induced plasma atomic emission spectrometry (HG-MIP-AES).The accuracy of the method was in the range of 95%–97%; the intra-assay precision was within the range of 1.8%–6.2% expressed as the relative standard deviation, and the interassay precision was within 6.9%–15%. The limits of detection and quantification were 1.8 and 5.4 μg L−1, respectively.The validated method resulted very helpful to assess the health risk of As exposure through drinking water and was successfully applied in urine samples collected from wood impregnation plant workers. The methodology can be postulated as a viable alternative to expensive techniques, such as liquid chromatography (HPLC) in combination with inductively coupled plasma mass spectrometry (ICP-MS), for biomonitoring studies.

Multi-energy calibration for determining critical metals in nickel-metal hydride battery residues by microwave-induced plasma atomic emission spectrometry.

Nickel-metal hydride batteries (NiMH) are a secondary source of high aggregate value elements, such as nickel, manganese, cobalt, and rare earths, for which recycling typically involves acid lixiviation. Designing the recycling process requires accurate determination of the elements in the leachates, which is hindered by the high complexity of the matrix. In the present study, microwave-induced plasma atomic emission spectrometry (MIP-OES) was selected as the quantitative method for elemental analysis because of its environment friendliness and cost-effectiveness. Multi-energy calibration (MEC) was also pioneeringly evaluated to circumvent matrix effects and simplify the determination of Ce, La, Ni, Co, and Mn in sulfuric acid leachates of NiMH batteries by MIP-OES. The method's analytical performance and accuracy were critically compared with external standard calibration and the standard additions method. MEC yielded superior results, with analyte recoveries within 90-110%, precision (coefficients of variation) from 1.8% to 5.8%, and limits of detection of 10, 20, 1, 400, and 60 μg kg-1 for Ni, La, Mn, Ce, and Co, respectively. The results demonstrated the ability of MEC-MIP-OES to minimize matrix effects, as well as simplify and speed up the analysis of NiMH battery leachates, which is compatible with this high-demand analytical application.

Multielement Determination of Trace Heavy Metals in Water by Microwave-Induced Plasma Atomic Emission Spectrometry after Extraction in Unconventional Single-Salt Aqueous Biphasic System.

For the first time liquid-liquid extraction was used for the preconcentration of heavy metals prior to their determination in water by microwave-induced plasma atomic emission spectrometry (MP-AES). Extraction of Pb(II), Cd(II), Co(II), Ni(II), Zn(II), and Cu(II) was performed in unconventional aqueous biphasic system (ABS) formed by addition of hydrophobic solid salt, namely, tetrahexylammonium bromide, to aqueous sample, with neither organic solvents nor salting-out agents being used. The metal ions were quantitatively recovered with 4-(2-pyridylazo)-resorcinol (PAR). The extract was diluted with ethanol/HCl and introduced directly into an MP-AES instrument. The factors influencing extraction (pH, reagent concentration, phase contact time, etc.) and MP-AES detection parameters were studied and optimized. For the developed method, limits of detection of 1.3, 4.9, 0.06, 1.2, 4.2, and 3.2 μg L-1 were obtained for cadmium, cobalt, copper, nickel, lead, and zinc, respectively, providing from 60- to 500-fold improvement as compared with the analysis without preconcentration. The method was applied for the analysis of two certified reference materials (CRM) of wastewater and surface water as well as the samples of well and seawater. Coupling MP-AES with ABS extraction significantly extends the capabilities of the method, especially for the analysis of high salinity waters.

Nutritional analysis of Spirulina dietary supplements: Optimization procedure of ultrasound-assisted digestion for multielemental determination

Arthrospira platensis and Arthrospira maxima are a type of blue-green microalga used as a dietary supplement (Spirulina). A low time-consuming ultrasound-assisted digestion (UAD) of Spirulina supplements for multielemental determination by microwave induced plasma atomic emission spectrometry (MPAES) was performed. Several parameters such as acid concentration (AC), thermostated water bath (TWB), digestion time (DT) and UAD – probe or bath – affecting the digestion process were evaluated through a full factorial design. Under the optimal conditions −100 °C for TWB, 5% for AC and 10 min for DT- and selecting the bath as the proper UAD system, the concentrations of 15 analytes (Al, Ba, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, V, Zn) were reported. The values are in accordance with the recommendation established by Food and Drug Administration (FDA) excepting for Cd. The knowledge of Spirulina multielemental composition contributes to an outstanding nutritional and toxicological report for human health.

Development of a general acid method for the digestion of gold ore samples together with a comparison of extraction solvents for gold and determination by microwave-induced plasma-atomic emission spectrometry (MIP-AES)

In this paper, we explore a variety of aqueous digestion techniques for the determination of gold in a wide variety of mineral matrices.

Identification of toxic metals in human embryonic tissues.

IntroductionThe cause of a significant number of miscarriages remains unexplained. There is a need to identify the potential role of environmental, dietary and lifestyle factors in the risk of pregnancy loss. The present study was the first to investigate the content of miscarried embryonic material with respect to eight metals (aluminium, cadmium, chromium, copper, manganese, nickel, lead and zinc).Material and methodsEmbryonic tissue samples (n = 20) were obtained from women undergoing misoprostol-induced removal of the embryo between the 6th and 9th week of gestation. The content of metals was analyzed using microwave-induced nitrogen plasma atomic emission spectrometry. Based on a short questionnaire, the smoking habits, dietary patterns and place of living of the investigated women were determined.ResultsThe general mean content of metals (μg/g) decreased in the order copper (33.9) > manganese (24.7) > chromium (13.6) > zinc (13.3) > aluminium (6.5) > nickel (3.0) > lead (2.9) > cadmium (2.5). Profoundly increased concentrations (p < 0.05) of the toxic elements aluminium (over 5-fold), cadmium (over 2-fold) and lead (over 2-fold) were observed in samples obtained from former smoking women. The miscarried material in urban populations also revealed higher levels of cadmium (over 1.5-fold) and lead (over 2-fold) compared to that obtained from women living in rural areas (p < 0.05). No associations with age or diet were found (p > 0.05).ConclusionsThis study identified increased levels of aluminum, cadmium and lead in miscarried embryonic material and suggests some causative factors.

Detection of Fine-particles in Suspension by Time-resolved Helium Microwave-induced Plasma Atomic Emission Spectrometry

微粒子（≤10000 nm）の組成はじめ構成元素や粒子の数とその大きさを同時に測定する方法を開発するために，表面波励起型のOkamoto cavityを用いて，大電力領域（≤700 W）で生成した大気圧ヘリウムマイクロ波誘導プラズマ（He-MIP）に微粒子を導入して励起・発光させたときの基本特性を，時間分解原子発光分析法を用いて検討した．微粒子を純水中に分散させて懸濁液とし，これをネブライザーで霧化してHe-MIPの中心部に導入した．このときの各微粒子からの発光パルスを複数の分光器を用いて時間分解すると，その同期性から組成が，その波長から元素が，そのパルスの数から粒子数が，そしてその強度から粒子径が分かる．微粒子としてはAg（メジアン径: 368, 518, 833, 1304 nm）とAl2O3（409 nm）とBaTiO3（2062 nm）及びFly-Ash（BCR-038, 5413 nm，成分: As, Cl, Co, Cr etc.）を用いた．この方法によって，懸濁液中のこれらの微粒子を高感度で検出することができた．

Solid-phase microextraction followed by gas chromatography for the speciation of organotin compounds in honey and wine samples: A comparison of atomic emission and mass spectrometry detectors

An environmentally friendly method for the determination of seven organotin compounds in honey and wine samples, using headspace solid-phase microextraction (HS-SPME) and gas chromatography (GC), was developed. The analytes were derivatized in situ with sodium tetraethylborate, and the derivatization and preconcentration steps were optimized. A 100μm polydimethylsiloxane fiber was the most suitable for preconcentrating the derivatized analytes from the headspace of an aqueous solution containing the sample. When microwave-induced plasma atomic emission (MIP-AED) and mass spectrometry (MS) detection were compared, higher sensitivity was attained for all compounds with MS, although MIP-AED showed more specific chromatograms. Using MS, detection limits ranged roughly from 0.3 to 4.3pg(Sn)/g, depending on the compound for honey samples, and from 0.1 to 2pg(Sn)/mL for wine samples. The optimized method was successfully applied to different samples, and the compounds studied were detected in some wines at 0.05–5ng(Sn)/mL levels.

Rapid Determination of Gold in MIBK Extracts Using Okamoto-cavity Microwave-Induced Plasma Atomic Emission Spectrometry

Rapid Determination of Gold in MIBK Extracts Using Okamoto-cavity Microwave-Induced Plasma Atomic Emission Spectrometry

Spectrochemical determination of trace As, Fe, Hg, Mn, and Pb by an argon-stabilized U-shaped DC arc

Argon-stabilized U-shaped DC arc with a system for aerosol introduction was used for the determination of As, Fe, Hg, Mn, and Pb. By applying a computer program performing a time integration of the registered signals and by optimizing the working conditions of an U-shaped arc plasma, the detection capability for As, Fe, Hg, Mn, and Pb was improved, which contributed to the lowering of the detection limits. The lowest detection limits for Fe, Mn, and Pb were achieved during an integration time of 20 s, and for As and Hg during an integration time of 30 s, and their values were 1.1, 0.1, 0.9, 15, and 2.6 ng/mL, respectively. The detection limits obtained by our method with optimal integration times were compared with the detection limits obtained using other methods: inductively coupled plasma-atomic emission spectrometry (ICP-AES), directly coupled plasma-atomic emission spectrometry (DCP-AES), microwave-induced plasma-atomic emission spectrometry (MIP-AES), inductively coupled plasma-mass spectrometry (ICP-MS), and an improved thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS).

Determination of As in tree-rings of poplar (Populus alba L.) by U-shaped DC arc

An argon-stabilized U-shaped DC arc with a system for aerosol introduction was used for determination of As in poplar (Populus alba L.) tree-rings. After optimization of the operating parameters and selection of the most appropriate signal integration time (30 s), the limit of detection for As was reduced to 15.0 ng/mL. This detection limit obtained with the optimal integration time was compared with those for other methods: inductively coupled plasma-atomic emission spectrometry (ICP-AES), direct coupled plasma-atomic emission spectrometry (DCP-AES), microwave induced plasma-atomic emission spectrometry (MIP-AES) and improved thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS). Arsenic is toxic trace element which can adversely affect plant, animal and human health. As an indicator of environment pollution we collected poplar tree-rings from two locations. The first area was close to the "Nikola Tesla" (TENT-A) power plant, Obrenovac, while the other was in the urban area of Novi Sad. In all cases elevated average concentrations of As were registered in poplar tree-rings from the Obrenovac location.

Determination of Fe, Hg, Mn, and Pb in three-rings of poplar (Populus alba L.) by U-shaped DC arc

The U-shaped DC arc with aerosol supply was applied for the determination of Fe, Hg, Mn, and Pb in poplar (Populus alba L.) tree-rings. By optimization of the operating parameters and by selection of the most appropriate signal integration time (20 s for Fe, Mn, and Pb and 30 s for Hg), the obtained limits of detection for Fe, Hg, Mn, and Pb are 5.8, 2.6, 1.6, and 2.0 ng/ml, respectively. The detection limits achieved by this method for Fe, Hg, Mn, and Pb are comparable with the detection limits obtained for these elements by such methods as inductively coupled plasma-atomic emission spectrometry (ICP-AES), direct coupled plasmatomic emission spectrometry (DCP-AES), and microwave-induced plasma-atomic emission spectrometry (MIP-AES). We used the tree-rings of poplar from two different locations. The first one is in the area close to the power plant “Nikola Tesla” TENT A, Obrenovac, while the other one is in the urban area of Novi Sad. In almost all cases, samples from the location at Obrenovac registered elevated average concentrations of Fe, Hg, Mn, and Pb in the tree-rings of poplar.

A sensitive solid-phase microextraction/gas chromatography-based procedure for determining pentachlorophenol in food

A new method for the determination of pentachlorophenol (PCP) in different foods was developed using capillary gas chromatography (GC) and microwave induced-plasma atomic emission spectrometry (MIP-AED). The analyte is first derivatized and then extracted and pre-concentrated by solid-phase microextraction (SPME) in headspace (HS) mode. A clear matrix effect was found for the different samples investigated, so that standard addition was required for quantification. Detection limits of 0.03–6.0 ng g−1 were obtained, depending on the sample analysed. The method gave recoveries of 81–109% from spiked samples. Concentration levels of PCP ranged from 0.3 to 1.5 ng g−1 were found in honey, but no PCP was detected in other samples.

非金属元素分析のためのヘリウム大気圧マイクロ波プラズマ発光分光分析法

The accurate determination of trace elements in steel is an important and challenging task in analytical chemistry. The variation of the contents of nonmetal elements such as C, P and S in steel can have a significant influence on the mechanical and physical properties. A sensitive and accurate method for the determination of these elements in steels is therefore required.The aim of the present work is to develop an accurate method using He-MIP AES (Helium Microwave-Induced Plasma Atomic Emission Spectrometry) to determine the trace amounts of these elements in the gas, liquid and solid samples. The optimization of the He-MIP AES technique and its analytical figures of merit, as well as its application to the determination of these elements in the samples, were described. The samples were transported and excited in a microwave induced helium plasma operated at atmospheric pressure.A high-power (∼1000 watt CW, 2.45 GHz) annular-shaped microwave-induced helium plasma (He-MIP) was developed for the determination of nonmetals in the aqueous solutions, and the characteristics were presented. The plasma was generated at atmospheric pressure by an Okamoto cavity of the surface wave mode. No external cooling was used to stabilize the plasma. The electron density and iron-excitation temperature were on the order of 1014/cm3 and 6500K, respectively. An air for gas sample was aspirated with an aspirator and introduced directly into the He-MIP. Carbon (247.9 nm) in the air was detected. An aqueous solution was injected into the plasma by an ultrasonic system with desolvation and condensation. Introduction of aqueous fluoride in the form of NaF, chloride in the form of NaCl and bromide in the form of KBr produced intense emission and detection limits of 100 ppb for FI (685.6 nm), Cl II (479.5 nm) and 150 ppb for Br II (470.5 nm) were obtained. Detection limits of the carbon and phosphorous in the aqueous solution were 1 ppb and 2 ppb, respectively.

Gas chromatography with atomic emission detection for dimethylselenide and dimethyldiselenide determination in waters and plant materials using a purge-and-trap preconcentration system

Dimethylselenide (DMSe) and dimethyldiselenide (DMDSe) were determined in plant and water samples by capillary gas chromatography using microwave induced-plasma atomic emission spectrometry for detection. The analytes were leached from the solid samples into methanol by using an ultrasonic probe, and a portion of the extract was preconcentrated by means of a purge-and-trap system before being chromatographed. The analytes were directly purged from the water samples in the presence of 6% (v/v) methanol. Element-specific detection and quantification was carried out by monitoring the selenium (196 nm) emission line. Calibration curves were obtained by plotting peak area versus concentration and the correlation coefficients for linear calibration were 0.9999 for both analytes. Detection limits of 0.8 and 1.1 ng l −1 were obtained for DMSe and DMDSe, respectively, for water samples. For plant materials, the detection limits calculated for 0.5 g samples were 0.3 and 0.4 ng g −1 for DMSe and DMDSe, respectively. Concentration levels of DMSe ranging from 1.2 to 4.2 ng g −1 were found in some of the plant materials analyzed. No DMDSe was found in any of the samples. The accuracy of the method was checked by analyzing different spiked water and plant samples.

Multielement determination of heavy metals in water samples by continuous powder introduction microwave-induced plasma atomic emission spectrometry after preconcentration on activated carbon

A novel continuous powder introduction microwave-induced plasma atomic emission spectrometry method (CPI-MIP-AES) has been developed for trace determination of metals in ground and tap water samples after preconcentration on activated carbon. The experimental setup consisted of integrated rectangular cavity TE 101 and vertically positioned plasma torch. The technical arrangement of the sample introduction system has been designed based on the fluidized bed concept. The satisfactory signal stability required for sequential analysis was attained owing to the vertical plasma configuration, as well as the plasma gas flow rate compatibility with sample introduction flow rate. The elements of interest (Cd, Cu, Cr, Fe, Mn, Pb, Zn) were preconcentrated in a batch procedure at pH 8–8.5 after addition of activated carbon and then, after filtering and drying of the activated carbon suspension, introduced to the MIP by the CPI system. An enrichment factor of about 1000-fold for a sample volume of 1 l was obtained. The detection limit values for the proposed method were 17–250 ng l −1. The proposed method was validated by analyzing the certified reference materials: SRW “Warta” Synthetic River Water and BCR CRM 399 major elements in freshwater. The method was successfully applied to the determination of the heavy metals in tap water samples.

Speciation of organotin compounds in waters and marine sediments using purge-and-trap capillary gas chromatography with atomic emission detection

A procedure for the simultaneous determination of six organotin compounds, including methyl-, butyl- and phenyltins, in waters and marine sediments is developed. The analytes were leached from the solid samples into an acetic acid:methanol mixture by using an ultrasonic probe. The organotins were derivatized with sodium tetraethylborate (NaBEt 4) in the aqueous phase, stripped by a flow of helium, pre-concentrated in a trap and thermally desorbed. This was followed by capillary gas chromatography with microwave-induced plasma atomic emission spectrometry as the detection system (GC–AED). Each chromatographic run took 22 min, including the purge time. Calibration curves were obtained by plotting peak area versus concentration and the correlation coefficients for linear calibration were at least 0.9991. Detection limits ranged from 11 to 50 ng Sn l −1 for tributyltin and tetramethyltin, respectively. The seawater samples analyzed contained variable concentrations of mono-, di- and tributyl- and monophenyltin, ranging from 0.05 to 0.48 μg Sn l −1, depending on the compound. Some of the sediments analyzed contained concentrations of dibutyl- and tributyltin of between 6.0 and 13.0 ng Sn g −1. Analysis of the certified reference material PACS-2, as well as of spiked water and sediment samples showed the accuracy of the method. The proposed method is selective and reproducible, and is considered suitable for monitoring organotin compounds in water and sediment samples.

Solid-phase microextraction-capillary gas chromatography combined with microwave-induced plasma atomic-emission spectrometry for selenite determination.

The use of solid-phase microextraction (SPME) with gas chromatography coupled to microwave-induced plasma atomic-emission detection (GC-MIP-AED) is described for selenite [Se(IV)] speciation. Aqueous standards were derivatised with sodium tetraethyl- or tetrapropylborate and extracted by SPME. Headspace extraction of the ethyl and propyl derivatives was studied. Relevant experimental conditions were optimised, including conditions for derivatisation and extraction and those of gas chromatographic analysis. The limits of detection achieved for headspace sampling of derivatised Se(IV) were in the low ng mL(-1) range for both ethylation and propylation. When the method was applied to analysis of selenite in selenised yeast reference material results were in good agreement with the indicated values.

Determination of volatile halogenated organic compounds in soils by purge-and-trap capillary gas chromatography with atomic emission detection

Nine volatile halogenated organic compounds (VHOCs), including four trihalomethanes (THMs), were determined in soils by capillary gas chromatography with microwave induced-plasma atomic emission spectrometry (GC-AED), using a purge-and-trap system (PT) for sample preconcentration. Analytes were previously extracted from the soil sample in methanol and the extract was preconcentrated before being chromatographed. Element-specific detection and quantification were carried out monitoring two wavelength emission lines, corresponding to chlorine (479nm) and bromine (478nm). Each chromatographic run took 21min, including the purge step. The method showed a precision of 1.1–7.2% (R.S.D.) depending on the compound. Detection limits ranged from 0.05 to 0.55ngml−1, for chloroform and dichloromethane, respectively, corresponding to 3.3 and 36.0ngg−1 in the soil samples. The chromatographic profiles obtained showed no interference from co-extracted compounds. Low levels of dichloromethane and chloroform ranging from 0.04 to 1.13μgg−1 were found in samples obtained from small gardens irrigated with tap water. The method is reliable and can be used for routine monitoring in soil samples.