Microwave Decomposition Research Articles

Microwave-induced combustion for further determination of potentially toxic elements in honey by ICP-MS.

Microwave-induced combustion (MIC) was proposed in this study for honey decomposition aiming for As, Cd, Hg, and Pb determination by inductively coupled plasma mass spectrometry (ICP-MS). Sample mass (up to 1.0g), absorbing solution (0.5 to 14.4mol L-1 HNO3, and H2O), heating program, and combustion aids were evaluated. The Eurachem guidelines were used for method validation. The proposed method enabled combustion of a high sample mass (0.8g of honey, with 0.4g of microcrystalline cellulose and 100 µL of 6mol L-1 NH4NO3) using 6mL of an absorbing solution consisting of 1mol L-1 HNO3, which resulted in low residual carbon in solution (< 25mg L-1). Honey samples from different geographical origins were analyzed. Results showed no significant difference in comparison to other two microwave decomposition methods, based on microwave-assisted wet digestion with single reaction chamber (MAWD-SRC) and microwave-assisted wet digestion (MAWD). Standard addition experiments resulted in recoveries higher than 98%. The limits of detection ranged from 1.10 (As) to 4.60ngg-1 (Pb). In addition to using only diluted reagents and resulting in digests virtually free of interferences, the proposed method was faster (< 30min) than most of those presented in the literature.

Analysis of cerium-substituted yttrium iron garnets by inductively coupled plasma atomic emission spectrometry with preliminary microwave decomposition

An analytical procedure for inductively coupled plasma atomic emission (ICP-AES) analysis of iron garnets of the composition Y3 – xCexFe5 – yGayO12, where x = 0.4 – 0.5 and y = 2.4 – 2.6 with preliminary microwave decomposition of the sample is described. The compositions of acid mixtures (HCl/HNO3), as well as modes of microwave heating (holding time and temperature), providing complete dissolution of the samples are proposed. In addition to optimized sample preparation, conditions for ICP-AES analysis of cerium-doped yttrium iron garnets were studied. The effect of matrix components (Y, Ce, Fe, Ga) on the determination of doping elements was revealed and studied. The operating parameters of the spectrometer (ICP power and nebulizer flow rate) have been substantiated, which make it possible to reduce the matrix effect of Fe, Ga, Y, Ce on the elements Na, Mg, Al, Si, P, K, Ca, Sc, Cr, Mn, Co, Ni, Cu, Zn, Se, Cd, Sn, Te, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Pb in iron yttrium garnets by the ICP-AES. ICP-AES measurements were performed in the axial and radial mode for trace elements and in the radial mode for matrix elements. The limits of quantification (LOQs) of most elements ranged within n × 10–5 – n × 10–4 wt.%. The accuracy is confirmed by the spike recovery test. The relative standard deviation is in the range of 1 – 5% depending on the selected plasma view mode and the analyzed analytes. The developed method makes it possible to determine macro- and microcomponents in yttrium iron garnets in a wide range of concentrations with a high accuracy.

TECHNOLOGICAL STUDIES OF A STANDARD SAMPLE OF RETINOL PALMITATE OBTAINED FROM NATURAL RAW MATERIALS

Relevance. One of the most common and popular reference samples used as reliable standards is retinol palmitate – vitamin A, which is widely used both in the food industry and in veterinary medicine, but this sample is especially popular when analyzing pharmaceutical products. However, this val-uable object still needs to implement a number of technological solutions, primarily related to the technology of its production from domestic natural raw materials, taking into account the extremely significant resource-saving factor today. For the first time, a species of fish successfully grown and cultivated in Russia – the salmon family – trout, as well as a representative of the flounder and mackerel breeds that are not cultivated, but exist in Russia, are considered as raw materials. This article discusses a method for obtaining the substance of vitamin A, which is actively used in pharmaceutical production. There are several known ways to obtain fat-soluble vitamin A both from natural raw materials and by synthesis. The article examines technological approaches with the use of innovative measures that increase the production attractiveness of the developed technological approach (technological scheme). The originality of these studies is based on the use of resource-saving technologies in the production of fat-soluble vitamins, which reduce the consumption of materials (reagents), labor and energy costs, by reducing the time for the main technological stage, as well as the possibility of using the resources of domestic enterprises for processing cultivated and wild fish species as a raw material base. The purpose of the work. To propose an original technology for obtaining vitamin A substance (retinol palmitate) using the domestic fish raw mate-rial base, and to identify and standardize the result obtained. Material and methods. The main object of the study is the type of fish actively grown on the territory of the Russian Federation. The main factors determining the choice of the object were such characteristics as the availability of the raw material base, the high fat content in the object and the relatively low cost of raw materials. In the production process, innovative methods of obtaining and cleaning the final product were also used, such as oxygen-free technological operations using the microwave exposure method. The identification of vitamin A in the samples was carried out using UV spectrometry, which confirmed the validity of the selected raw material object. Results. The use of innovative methods for isolating the substance from fish products using the effect of microwave decomposition of biological ma-terial in an inert gas environment has reduced the time of the main stage of production from an average of 180 minutes to 30. The production of substances from natural materials makes it possible to obtain a cleaner and, as a result, a more physiological product that does not require complex purification steps and does not have toxic micro-impurities in its composition. The developed method of obtaining vitamin A substance will make it possible to replenish the material base, which should exist as a constantly replen-ished resource. Special attention should be paid that the vitamin A substance can be used not only as a pharmaceutical substance, but can also find its application in the veterinary and food industries as a biologically active additive (dietary supplement) and as a reference material - a standard sam-ple (CO) for use in analytical practice (conformity assessment) and scientific research. Conclusions. Thus, for the first time, an original technology was developed for the production of retinol palmitate from natural domestic raw material – fish belonging to breeds cultivated in Russia. The optimal technology has been developed taking into account the resource-saving factor. In the pro-cess of technology, such innovative technological techniques as the use of oxygen-free grinding of raw materials, microwave radiation during hydroly-sis, the implementation of all technological stages in an inert gas environment have been developed.

Using Carbon Quantum Dots for the Determination of Aminoglycoside Antibiotics by Fluorescence Polarization Immunoassay

Conditions are studied for the synthesis of carbon quantum dots (CQD) exhibiting green fluorescence by the ultrasonic treatment of multilayered carbon nanotubes in a mixture HNO3 with H2SO4 (CQD-1) and by the microwave decomposition of 9,10-dinitroanthracene in ethanol (CQD-2). The sizes of COD are estimated by atomic force microscopy, and their optical properties, by spectrophotometry and fluorescence spectrometry. Infrared spectrometry was used to identify active functional groups on the CQD surface, participating in the formation of stable bonds in the synthesis of tracers. A possibility of using CQD as labels in fluorescence polarization immunoassay (FPIA) is shown. Procedures are developed for determining aminoglycoside antibiotics gentamycin, streptomycin, and amikacin by FPIA using a TDx-analyzer (Abbott Diagnostics, United States); their performance characteristics are presented. The limit of detection is (ng/mL) 20, 10, and 3, and the analytical range (µg/mL) is 0.05–3.00, 0.02–6.00, and 0.01–3.00 for gentamycin, streptomycin, and amikacin respectively. The procedures are tested in the determination of gentamycin, streptomycin, and amikacin in dairy products. Various labels, most often enzyme or fluorescent, are used to

A Rapid Determination Method of Metals in Foods for Emergency Response to Health Crisis

A rapid determination method for emergency response to health crisis caused by metals in foods, was developed using microwave decomposition equipment and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The method was assessed for 18 elements (Al, As, B, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Sb, Se, Sn, Tl and Zn) in 5 kinds of beverages and 7 kinds of foods. A single-laboratory method validation study was performed using food samples added with 20 mg/kg of each metal. Trueness was 88-108% and intralaboratory reproducibility was 0.2-11.3%. Time required for analysis was less than 3 hr. Thus, the presented method could be useful for rapid analysis of metals involved food poisoning cases.

Development of ICP-AES method for analysis of iron ore raw materials

A method for the determination of Fetot, SiO2, P, V2O5, TiO2, Cr2O3, Ni, Cu, Zn in iron ore raw materials (i.e., pellets, iron ore agglomerate, aspiration dust and slag component of a scrap) by the method of atomic emission spectrometry with inductively coupled plasma (ICP-AES) has been developed using microwave sample preparation in analytical autoclaves. The composition of the acid mixture for the complete dissolution of the sample component, as well as the parameters of microwave decomposition, excluding the depressurization of the autoclave and the loss of sample elements which form volatile compounds are proposed. The developed method of microwave sample preparation in closed autoclaves makes it possible to decompose iron ore samples using the minimum amount of acid (17 cm3) in 45 min. Conditions for the determination of normalized elements in iron ore samples by the ICP-AES method after microwave sample preparation were determined: the operation parameters of the spectrometer were optimized, the analytical lines of each determined element free from spectral overlaps were selected, the efficiency of using cadmium as an internal standard was experimentally proved. The equations for calibration dependences and the ranges of determinable contents are presented. When using cadmium as an internal standard in the analysis of iron ore, a decrease in the value of the standard deviation from 0.17 to 0.04 is observed when determining Cr2O3; from 0.02 to 0.004 when determining Fe; from 0.03 to 0.002 when determining SiO2; from 0.015 to 0.008 when determining TiO2; and from 0.17 to 0.02 when determining V2O5. The correctness of the determination of the standardized elements by the developed method is evaluated, using certified reference samples (CRS) similar in composition to the analyzed material. The results of determining the standardized elements according to the developed methodology were compared with the data obtained using GOST-approved methods of analysis, and then checked in accordance with the Recommendations of RMG 76–2014. The developed ICP-AES technique is characterized by a wider linear range of the determined concentrations than that in GOST-approved techniques, thus providing determination of the components in iron ore raw materials that could not be controlled before.

Selected gas response measurements using reduced graphene oxide decorated with nickel nanoparticles

The work reports the synthesis of nickel nanoparticles supported on thermally reduced graphene oxides (rGO) in the ionic liquid [BMIm][NTf2] through microwave decomposition reaction. [email protected] with the polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) as binder was positively tested for its response towards the oxidizing gas nitrogen dioxide (10 ​ppm in air), the reducing gas carbon monoxide (3000 ​ppm in N2) and the volatile organic compound (VOC) acetone (35,000 ​ppm in air). The results from different gases were compared at different temperatures with the best results for NO2 at 200 ​°C. Additionally, it is shown for NO2 gas that the [email protected]:PSS polymer composite gives better results than the rGO-PEDOT:PSS polymer composite. After the heat treatment the oxidation state of pure nickel nanoparticles were confirmed by powder diffraction.

Novel Determination of Trace Metals in Geological Materials Employed in Food Products by Microwave Decomposition and Inductively Coupled Plasma – Optical Emission Spectrometry (ICP-OES)

A new methodology for the determination of trace metals in geological materials employed in the food industry by single-reaction chamber (SRC) microwave digestion followed by inductively coupled plasma – optical emission spectrometry (ICP-OES) analysis was developed. The presence of toxic elements for human beings, such as As, Cd, Cr, Hg, Ni, and Pb, must be controlled in those materials that are in contact with food. Most regulations require the presence of these elements in these materials in low concentrations, mostly less than 1 mg kg−1, which requires analytical methodologies that can reach these quantification limits. In the optimization of the sample preparation by microwave digestion, different mixtures of acids were used, so that As, Cd, and Hg were decomposed in an inverse aqua regia solution, while extraction of solid sample with aqua regia and HF was needed to determine Cr, Ni, and Pb. The determination of the analytes present in these solutions was carried out by ICP-OES, optimizing the conditions to obtain the best signal-to-noise ratio for each analyte. The study was undertaken using certified reference materials, two samples of clay, and a sample of sepiolite. Quantification limits of 1 mg kg−1 were achieved, which meet the legal requirements. The analyzed samples of clays and sepiolite contained values of Cd and Hg that met the requirements although the results for As, Cr, Ni, and Pb were above the limits required for the food industry.

Modern Methodological Approaches to Sample Preparation for the Determination of Trace Elements in Food Products and Plant Raw Materials

Introduction. Various copper compounds are most widely used as plant protection agents in agriculture. From a hygienic point of view, information on excessive accumulation of copper in plants related to the use of a specific formulation of copper-containing pesticides is of interest. Our objective was to assess feasibility of increasing statistical significance of results of determining low residue levels of a copper-containing pesticide in apple samples by flame atomic absorption spectrometry using a high-resolution spectrometer in combination with developed approaches to sample preparation of plant-based foods, including homogenization with dry ice and microwave mineralization. Materials and methods: We analyzed 30 samples of apples collected in three different agro-climatic zones by flame atomic absorption spectrometry and electrothermal atomization atomic absorption spectrometry. Both methods were validated on 10 samples with added copper at levels 1-5 of the lower limit of quantitation. A statistical calculation was performed based on a simple Student’s test to assess the significance of differences between the results of measurements by flame and electrothermal techniques. Homogeneity of variances was estimated using the Fisher test to clarify the possibility of comparing two data sets. Results: The use of a technique of cryo-grinding and microwave decomposition in a microwave reactor in combination with a high-resolution continuum source atomic absorption spectrometry demonstrated a decrease in scattering and the limit of detection and better repeatability in the analysis of parallel samples. Results of statistical calculations confirmed the homogeneity of variances in data samples obtained for electrothermal and flame techniques, and the further Student’s t-test showed insignificant differences between the results of measurements obtained by FAAS and ET-AAS. Conclusion: Our findings prove that modern methods of sample preparation in combination with highly sensitive equipment allow a significant reduction in the limit of detection and scattering of test results.

THE NEWEST ANALYTICAL TECHNOLOGIES FOR DETERMINING RARE-EARTH ELEMENTS IN GRANITOIDS OF THE UKRAINIAN SHIELD

Introduction. To date, rare earth elements (REE) are used to manufacture most high-tech goods and are crucial in defense technologies (lasers, radars, and electromagnetic weapons), nuclear engineering, metallurgy, and others. All this determines the relevance of their study to assess the rare earth mineral resource base of Ukraine. Problem Statement. The determination of REE in rocks and minerals is a fundamental problem in geochemistry and petrology for understanding the processes of rock formation. However, it is a complex analytical task related to the similar chemical properties of these elements, which are caused by the "lanthanide compression effect". Purpose. The purpose is to develop analytical technologies for determining REE content by the ICP-MS method, to evaluate their content and distribution in granitoids of the Ukrainian Shield. Materials and Methods. The hybrid method of ICP-MS analysis and microwave decomposition of rocks and minerals has been used to measure the REE content. This technique has been tested and used to estimate the content and distribution of REE in fluorites and rare-metal granitoids of the Rusko-Polyanskyi massif of the Korsun-Novomirgorod pluton of the Ukrainian Shield. Results. Analytical technologies for determination of REE in granites and minerals have been developed. The method for determining REE in fluorites and granites without their prior concentration in the range from 0.01 to 1000 ppm with a relative standard deviation of 0.01–0.10 has been described. The content of rare earth elements in the Rusko-Polianskyi granites increases (218–797 g/t), the main concentrator of these elements is fluorite (692–26933 g/t REE). An inverse relationship has been observed between the REE content in fluorites and granites. Conclusions. The developed analytical technologies are the basis for establishing quality assessment criteria and developing principles for the rational use of rare-earth granitoids to create a rare-earth mineral resource base in Ukraine.

Multielement Analysis of Oil by ICP–AES and ICP–MS with Microwave-Assisted Sample Preparation

To obtain detailed information on the elemental composition of oil, we developed ICP–AES and ICP–MS procedures for the determination of a wide range of elements in oil after microwave sample digestion. We found a possibility and selected the conditions of the microwave decomposition of samples of light and superviscous oils, weighing up to 1000 mg. The effect of residual acidity and residual carbon on the formation of an analytical signal in ICP–AES and ICP–MS (high resolution) was studied. We found that 20 elements can be determined by ICP–AES at a level of n × 10–2–m × 102 μg/g and 42 elements can be determined by ICP–MS at a level of n × 10–2–m × 102 ng/g.

Evaluation of the use of the PLP-01M microwave laboratory system using working samples to control the accuracy of the results of examining product samples for lead content

In order to compare the results obtained when working on the Kvant-2AT atomic absorption spectrometer, taking into account the use of the PLP-01M microwave laboratory system and during sample preparation in accordance with GOST 26929 “Raw materials and food products. Sample preparation. Mineralization to determine the content of toxic elements”, on the working samples, the products were selected that most fully covered the range of results obtained during the research. Within 30 working days, a set of research results and analysis of data obtained during operation on the Kvant-2AT atomic absorption spectrometer, taking into account the use of the PLP-01M microwave laboratory system and during sample preparation in accordance with GOST 26929, were carried out. Average values obtained under conditions repeatability were recorded in the table. In order to assess the accuracy of the obtained values, the analytic, lead, was added. The implementation of sample preparation methods taking into account the microwave decomposition of the sample in the case of using the PLP-01M microwave laboratory system and during sample preparation in accordance with GOST 26929-94 achieves the precision of the analysis results both under conditions of repeatability and under conditions of intermediate precision.

Control by the accuracy of the results of studies for the cadmium content in samples applying the microwave laboratory system PLP-01M

The article states that in order to compare the results obtained while operating on the atomic absorption spectrometer “Kvant-2AT” applying the microwave laboratory system PLP-01M and during the sample preparation in accordance with GOST 26929 “Raw materials and food products. Sample preparation. Mineralization to determine the content of toxic elements”, on operating samples, the products were selected that most fully cover the range of results obtained during the research. Some research results and data analysis were carried out within 30 operating days. The data were obtained while working on the Kvant-2AT atomic absorption spectrometer, taking into account the application of the PLP-01M microwave laboratory system and while the sample preparation in accordance with GOST 26929. The average values obtained under repeatability conditions were put in the table. The analyte cadmium was supplemented to assess the accuracy of the obtained values. The implementation of sample preparation methods taking into account the microwave decomposition of the sample in the case of using the microwave laboratory system PLP-01M and while sample preparation in accordance with GOST 26929-94 achieves the precision of the analysis results both under conditions of repeatability and under conditions of intermediate precision.

Rapid analysis of minerals in oysters using microwave decomposition and inductively coupled plasma atomic emission spectrometry

Oysters are rich in nutrients and can be cultivated in oceans; therefore they have attracted considerable interest as a food source. In this study, we investigated the rapid analysis of multiple minerals in oysters using microwave decomposition combined with inductively coupled plasma atomic emission spectrometry. Because all body parts of oysters other than the shell are edible, we homogenized all the edible parts and used them as samples. Multiple sample masses and acid-digestion formulations (nitric acid only and nitric acid with hydrogen peroxide) were evaluated in a microwave decomposition step using zinc as the target analyte. The levels of calcium, potassium, sodium, and magnesium were also studied. Microwave digestion using nitric acid and hydrogen peroxide yielded slightly higher mineral concentration results than those obtained with nitric acid alone. The mineral composition of oysters varies with the cultivation location and season. With the establishment of an appropriate database, the proposed method for the evaluation of mineral content could be used for rapidly determining the origin of oysters.

Determination of Cadmium and Chromium in Fruit Spirits Intended for Own Consumption Using Graphite Furnace Atomic Absorption Spectrometry.

Analysis of the occurrence of cadmium and chromium in selected samples of fruit spirits intended for own consumption. In our pilot study, we analysed 89 samples of fruit spirits intended for own consumption. The samples were mineralized with use of microwave decomposition system MULTIWAVE 60 50 Hz and analysed by atomic absorption spectrometry with a graphite furnace (AAS GBC XPLORAA 5000 with GF 5000). Most of the analysed samples originated from plums (39), apples (38) and pears (5). The average ethanol concentration was 53.7%. Cadmium and chromium were detected in all samples. The highest concentration of chromium and cadmium was found in the apple spirit (31.9 ± 6.6 μg/l and 40.1 ± 8.3 μg/l). The ethanol concentration in the samples was higher than in distribution spirits. Concentrations of chromium in all samples did not exceed the limit given by the Slovak legislation or the limit of the AMPHORA. The permissible cadmium concentration (10 μg/l according to the AMPHORA) was exceeded in 9 samples. This indicates the potential importance of cadmium compared to chromium. Due to the lack of information in this field, the study presents an important starting point for further research.

Particularity of chemical preparation of bottom sediment samples for multi-element ICP-MS analysis

Various techniques have been tested (multi-acid microwave decomposition and sintering with soda) for preparing samples for the analysis of ICP-MS for samples with a complex matrix including an organic component for the subsequent determination of the microelement composition. For research, we used samples of bottom sediments: terrigenous clay (SDO-1), volcanic-terrigenous silt (SDO-2), calcareous silt (SDO-3), ferromanganese nodules (SDO-5), Baikal silt (BIL-1) and complex sediment sample of Baikal (BIL-2). The most effective sample preparation methods for the studied rock type are proposed.

Thermal decomposition of struvite pellet by microwave radiation and recycling of its product to remove ammonium and phosphate from urine

The precipitation of struvite (MgNH4PO4·6H2O) consumes many chemicals to completely remove ammonium and phosphate from urine and has the difficulty in solid separation from solution. This study proposed an alternative approach for the complete nutrient removal through recycling use of microwave-induced decomposition product of struvite pellet with sizes of 2–4 mm. Results showed that microwave radiation effectively decomposed the struvite pellet in an alkaline solution within 8 min. An increase in microwave power and NaOH concentration enhanced the decomposition. The double-layer structure of the pellet led to multiple paths of struvite decomposition. Active components of the decomposition product were newberyite, brucite, and amorphous MgNaPO4 and MgHPO4. The removal efficiencies of ammonium and phosphate from urine both reached 93% using the decomposition product at optimized P/N ratio and pH. Maximum recycles of 4 were recommended because further decomposition of the regenerated struvite pellets induced high losses of magnesium and phosphate. Calculations showed that the total cost of chemical consumption of the proposed approach was reduced by 47% compared with that of a conventional chemical struvite precipitation. Moreover, the volume index of the regenerated struvite pellets was 15 mL/gP which was much lower than that of conventional struvite fines (116 mL/gP), thereby indicating a better solid-liquid separation ability. Therefore, recycling of struvite pellets combining with microwave decomposition was chemical saving and easily separating of solid from liquid for the complete removal of nutrients from urine.

Evaluation of the Zr, Y, and Gd Contents in Targets for Magnetron Spraying of Heat-Shielding Coatings Based on Zirconium

We proposed a method for the evaluation of the mass fraction of zirconium and rare-earth metals by the method of atomic-emission spectrometry with inductively bound plasma in zirconium-based alloys and ligatures. The proposed procedure includes the preliminary microwave preparation of samples of zirconium alloys and the choice of analytical lines for detection of elements of the alloy. We perform the choice of the composition of mixture for dissolution and the parameters of microwave decomposition and establish the main and alternative analytical lines of emission of the detected elements free of significant spectral overlays. The metrological characteristics of the method aimed at the evaluation of the mass fractions of zirconium and rare-earth metals are evaluated. The limits of the relative errors of measurements of the mass fractions of elements within the range 1–90% do not exceed ±2% with a confidence probability P = 0.95.

Analysis of Yttria-Stabilized Zirconia by Inductively Coupled Plasma Atomic Emission Spectrometry

A method for determination of aluminum, hafnium, iron, yttrium, calcium, magnesium, and titanium by inductively coupled plasma atomic emission spectrometry (ICP-AES) is described. Conditions for the decomposition of two modifications of the analyzed material—unburnt and subjected to stabilizing firing—have been studied. It has been found that the unburnt zirconia dissolves in sulfuric acid, and the burnt sample can be converted to solution only by fusing with potassium pyrosulfate or potassium bifluoride. However, the application of these reagents leads to high values of the control experiment correction for trace impurities (at the level of tenths and hundredths of a percent). In this connection, we have studied the possibility of acid dissolution of the burnt sample under microwave decomposition, varying the qualitative and quantitative composition of the acid mixture, reaction temperature, and time to reach and maintain the required temperature. It has been found that the decomposition in the mixture of hydrofluoric and sulfuric acids (2 : 1) in the microwave system with stepwise heating of the reaction mixture ensures quantitative dissolution of the burnt sample and sufficiently low values of the control experiment correction for trace impurities. The analytical lines have been chosen taking into account their relative intensity, possible spectral overlaps, and the matrix effect in the analysis of model solutions containing 1.3 mg/cm3 Zr, 0.2 mg/cm3 Y, and from 0.2 to 20 mg/cm3 impurities. As a result, the following analytical lines have been chosen: Al II 167.079 nm and Al I 308.215 nm, Ca II 184.006 nm and 393.366 nm, Fe II 238.204 nm, Mg II 279.553 nm, Ti II 334.941 nm, Y II 371.030 nm, and Hf II 232.247 nm. The developed method for the analysis of yttria-stabilized zirconia by ICP-AES allows simultaneously determining aluminum, iron, magnesium, and titanium in the range of 0.01–1.0%; calcium, 0.02–1.0%; hafnium, 0.1–5.0%; and yttrium, 2.0–15% with a relative standard deviation of 6–30 rel % (for Al, Fe, Mg, Ti, and Ca), 2–7 rel % (Hg), and 2–4 rel % (Y). The correctness of the method is confirmed by the standard addition technique.

A new and feasible analytical method using reversed-phase dispersive liquid-liquid microextraction (RP-DLLME) for further determination of Nickel in hydrogenated vegetable fat

A new and simple method for Ni determination in hydrogenated vegetable fat (HVF) has been developed using a RP-DLLME sample preparation procedure for further determination by flame atomic absorption spectrometry (FAAS) and graphite furnace atomic absorption spectrophotometry (GFAAS). The RP-DLLME procedure includes simultaneous microextraction and preconcentration of Ni in HVF, using 5.0 g of HVF preheated (75 °C) and diluted in 5.0 mL of xylene, with the addition of a dispersant/extractant mixture (n-propanol/dilute HNO3). The sample was manually stirred and centrifuged and the aqueous phase was collected for further Ni determination by FAAS and GFAAS. RP-DLLME was carried out using only 700 μL of n-propanol and 300 μL of 2.0 mol L−1 HNO3. The recovery varied from 93.3% to 101.5% for HVF. The LODs and LOQs were 40 and 90 ng g−1 for FAAS, and 0.41 and 1.36 ng g−1 for GFAAS. The proposed analytical method is viable and this is the first application of RP-DLLME to solid fat samples, with Ni determination as an example of application. This method consumes small amounts of reagents, with lower toxicity as compared to microwave decomposition. Furthermore, the key features of the RP-DLLME method include simplicity of operation, high sample mass, reduced reagent consumption, and use of diluted HNO3 as an extractant.