High-resolution Continuum Source Graphite Furnace Research Articles

Feasibility of matrix solid-phase dispersion combined with HR-CS FAAS for determination of copper in milk-based infant foods

This study proposes, for the first time, the development of an analytical method using the matrix solid-phase dispersion (MSPD) for extraction of copper from infant formulas and milk-based foods for further determination using high resolution-continuum source flame atomic absorption spectrometry (HR-CS FAAS). MSPD parameters were investigated, and by employing a 0.25 g sample, 0.25 g of diatomaceous earth as a solid support, 1 mol/L HNO3 as the extraction solution, and 1 min of blending, higher agreements with reference values were obtained. The limit of detection of the method was 0.35 µg/g. Accuracy was assessed by comparing the results using the following methods: i) proposed method (MSPD/HR-CS FAAS); and ii) decomposition of samples by microwave-assisted digestion (MAD) and quantification by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS). The MSPD extracts were also quantified using HR-CS GFAAS. No significant difference was found between the results. The agreements ranged from 95 to 103 %, and no significant difference was observed between the results. Copper concentrations ranged from 0.40 to 3.8 μg g−1 using the proposed method, with relative standard deviations lower than 10 %. The proposed method proved to be efficient for the determination of copper in infant formulas and milk powder, offering advantages such quickness, simplicity, low cost, low energy consumption, reduced waste generation (due to the use of an aqueous extraction solution), utilization of materials from renewable sources (diatomaceous earth as a solid support), and minimized analyst exposure when compared to conventional sample preparation methods. These attributes align with the principles of Green Analytical Chemistry.

A simple, fast and inexpensive approach to quantify low concentrations of iron in biodiesel by voltammetry after extraction induced by microemulsion breaking.

An alternative approach to assay iron (Fe) in biodiesel by differential pulse adsorptive cathodic stripping voltammetry (DPAdCSV) is presented herein. The sample treatment involved a simple, rapid, but effective extraction of Fe from biodiesel into an aqueous phase after microemulsion (ME) breaking. Then, Fe was determined as the complex Fe(III)-PAN (1-(2-pyridylazo)-2-naphthol) on a glassy carbon electrode (GCE) in the presence of bismuth (Bi(III)). The extraction induced by microemulsion breaking (EIMB) was achieved by adding 0.80 mL of ultrapure water into a water-in-oil ME containing 7.00 mL biodiesel, 2.70 mL n-propanol and 0.30 mL of 0.25 mol L-1 HNO3 solution. No deliberate addition of surfactant was necessary to form and maintain the ME. The EIMB resulted in a 1.30 mL lower aqueous phase extract (APhEx) and an upper oily phase. DP voltammograms were recorded with a portable potentiostat, showing the potentiality of carrying out the determination out of a central laboratory. Another feature was the non-necessity of deaerating the solution to eliminate the dissolved O2. The limits of detection (LOD) and quantification (LOQ) were 1.7 μg L-1 (140 mg kg-1) and 5.5 μg L-1 (455 mg kg-1), respectively. The accuracy of the method was evaluated by recovery assays of spiked samples, by analyzing a standard reference material and by comparisons with high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS).

Second-order calibration high-resolution continuum source graphite furnace molecular absorption spectrometry-based determination of bromine and fluorine

In this study, we report the simultaneous determination of bromine and fluorine using Second-Order Calibration High-Resolution Continuum Source Graphite Furnace Molecular Absorption Spectrometry (HR CS MAS). The instrumental data acquired correspond to the time versus wavelength matrix per sample that were analyzed using Parallel Factor Analysis (PARAFAC), along with Unfold and N-way Partial Least Squares combined with a post-calibration step known as Residual Bilinearization (U and N PLS/RBL). Despite the significant difference in sensitivity between bromine and fluorine, all approaches provided reasonably accurate results when predicting both analytes in synthetic mixtures within a controlled environment. The relative prediction error (REP) values for bromine were 29.8 % (PARAFAC), 23.6 % (N-PLS/RBL), and 13.1 % (U-PLS/RBL), while for fluorine, the REP values were 3.4 % (PARAFAC), 3.5 % (N-PLS/RBL), and 3.2 % (U-PLS/RBL). When applying this approach to predict unknown samples, a comparison was made between the estimated nominal concentrations of fluorine and bromine obtained using either a reference method or based on labeled values or spiked mass, and those obtained using the proposed method. It was observed that PARAFAC was unable to predict the samples accurately, whereas the REP values for the prediction of bromine and fluorine using N-PLS/RBL and U-PLS/RBL methods were 19.3 %/19.2 % and 13.6 %/13.1 %, respectively.

Sp-ICP-MS and HR–CS–GFAAS as useful available techniques for the size characterization and speciation of ionic and nanoparticular zinc in cosmetic and pharmaceutical samples

The use of zinc oxide nanoparticles (ZnO NPs) in cosmetic and pharmaceutical industry has been increased in recent years due to their good properties as solar radiation filters and antibacterial agent. According to the literature, the potential toxicity of these NPs could be size-dependent and the amount of solubilized metal. This work investigates new reliable and straightforward methodologies that enables the determination of ZnO NPs, discriminating them from ionic zinc in cosmetic samples. Two different techniques of analysis have been applied in this study: high-resolution continuum source graphite furnace atomic absorption spectrometry (HR–CS–GFAAS), and “single particle” inductively coupled plasma mass spectrometry (sp-ICP-MS). Triton X-100 has been used as a surfactant for the formation of homogeneous and stable slurries which allowed the determination of the concentration and sizes of ZnO NPs and Zn2+ in baby creams, eyeshadows, and lotions. A central composite design (CCD) was performed for the two techniques to optimize the concentration of Triton X-100 and sonication time. For validation purpose, the results of Zn2+ and ZnO NPs contents achieved by HR–CS–GFAAS were compared with the total Zn content obtained by acid digestion of the samples. A size comparison of the ZnO NPs was also carried out with the data obtained through the two methodologies and validated with transmission electron microscopy (TEM). In the case of TEM analysis, two different media were tried to study possible agglomerates and interactions between the particles and the matrix.

Determination of thallium in water samples via solid sampling HR-CS GF AAS after preconcentration on chromatographic paper

A method for determining thallium in water samples via solid sampling high-resolution continuum source graphite furnace atomic absorption spectrometry (SS HR-CS GF AAS) after preconcentration using chromatographic filter paper as a solid support was proposed. The effects of pH, stirring time, and sample volume in the analyte preconcentration step were studied. The presence of potential interferences in the sample and the type of masking agent were also examined. In the proposed procedure, the sample was placed in contact with the solid phase in a polypropylene tube, and after stirring for 3 min, thallium determination was performed via HR-CS GF AAS directly on chromatographic filter paper. A preconcentration factor of 55, a precision of 9.4% (n = 10; 10 μg L−1), a limit of detection of 0.018 μg L−1, and a limit of quantification of 0.059 μg L−1 were achieved. Analyte addition and recovery tests were performed, and the results ranged from 91% to 110%. The accuracy of the method was evaluated by analyzing a water reference material. The procedure was used to determine thallium in water samples collected in Barreiras, Bahia, Brazil. The results were compared with those obtained using inductively coupled plasma‒mass spectrometry (ICP‒MS). Thallium concentrations in the analyzed samples ranged from <0.059 to 0.80 μg L−1.

A Green Method for the Determination of Cadmium in Natural Waters Based on Multi-Fibre Supported Liquid Membranes.

Supported liquid membranes have been used to implement a hollow fibre liquid-phase microextraction (HF-LPME) method for the preconcentration of Cd(II) in natural waters as a sample preparation step for its determination by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS-GFAAS). This system was designed to use four hollow fibres simultaneously with the same sample, thus improving the simplicity, speed and reproducibility of the results. The organic liquid membrane bis-(2,4,4-trimethylpentyl) phosphinic acid (Cyanex® 272) dissolved in dihexylether (DHE) was immobilised into the pores of the walls of polypropylene hollow fibres. After extraction, the cadmium-enriched acidic phases were recovered and analysed by triplicate. To optimise the extraction process, the effect of both physical and chemical variables was studied, and optimum results with an enrichment factor (EF) of 292 were obtained for a fibre length of 6 cm, 1.06 M Cyanex 272, 0.04 M HNO3, stirring rate of 600 rpm and an extraction time of 4.26 h. For practical applications, extraction time was reduced to 2 h, keeping the EF as high as 130. Under these conditions, a detection limit of 0.13 ng L-1 Cd(II) was obtained, with a reproducibility of 3.3 % and a linear range up to 3 µg L-1 being achieved. The proposed method was successfully applied to the determination of cadmium in mineral, tap and seawater samples.

An environmentally friendly approach for the characterization of construction materials: determination of trace, minor, and major elements by slurry sampling high-resolution continuum source graphite furnace atomic absorption spectrometry.

A slurry sampling method was developed for the fast determination of Pb, Ni, Fe, and Mn in construction materials by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS). For sample introduction into the GF, stable slurries were prepared by sonicating 10 mg of ground solid sample in 10.0 mL of 1% (v/v) Triton X-100 and 1% (v/v) HNO3 solution for 1.0 min. The determination of the four elements was carried out in three measurement runs, with Ni and Fe being determined simultaneously. The HR-CS GFAAS measurements were performed using analytical lines with adequate sensitivity, considering the content of each element in the material: Pb at 283.306 nm (42%), Mn at 403.080 nm (6.7%), Ni at 232.003 nm (100%) and Fe at 232.036 nm (1.4%). The pyrolysis and atomization temperatures and the use of chemical modifiers were optimized using both aqueous standards and slurry samples. At optimal conditions, samples with concentrations of Pb from 1.5 to 80 μg g-1, Ni from 4.0 to 75 μg g-1, Mn from 2.0 to 600 μg g-1, and Fe from 0.15 to 60 mg g-1 could be determined using a unique sample suspension. To assess the validity of the method, a fly ash certified reference material (CRM) was analysed using the slurry sampling HR-CS GFAAS method; this CRM and the construction material samples were also analysed by HR-CS GFAAS after the digestion of the samples. The obtained results using both methods were statistically comparable (Student's paired t-test for two independent methods at a 95% confidence level) demonstrating the suitability of the proposed method.

Application of Disposable Pipette Extraction for Determination of Yb by High‑Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry Using Lanthanum as a Chemical Modifier

The use of extraction technique with disposable tips (DPX) was applied for the first time for the extraction and preconcentration of Yb in samples of liquid waste from the petrochemical industry and environmental water using bioabsorbent cork. The use of cork as an extracting phase in the determination of Yb by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) was evaluated. The pyrolysis and atomization temperatures were optimized at 1400 and 2400 ºC, respectively. H2SO4, HNO3 and HCl acids were compared in the steps of cleaning the extraction phase and desorption of the analyte by DPX. The best extraction in the selected conditions was obtained with pH 8.0 and 5% v/v HCl. The recoveries were close to 100% for residual water and drinking water, 33 to 77% for produced water and 64 to 93% for river water. Tests with interfering ions in different concentrations were performed. The relative limit of quantification (LOQ) and limit of detection (LOD) were estimated at 0.03 and 0.01 µg L-1, respectively. The total time for the preparation of the samples by DPX was close to 1 min per sample. Extraction and pre-concentration were observed using DPX with a preenrichment factor of approximately 4 times.

Determination of metallic elements in foods for enteral nutrition of chronic renal patients by atomic absorption spectrometry after extraction induced by emulsion breaking

This article describes the analysis of aluminum (Al), cadmium (Cd), copper (Cu), molybdenum (Mo), and lead (Pb) in foods for enteral nutrition of chronic renal patients by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS) after extraction induced by emulsion breaking. The following wavelengths were used for the detection of analytes 309.2713 nm for Al, 228.8018 nm for Cd, 324.7540 nm for Cu, 313.2594 nm for Mo, and 217.0005 nm for Pb. The detection limits for the methods were 0.022 mg kg−1 for Al, 0.0003 mg kg−1 for Cd, 0.001 mg kg−1 for Cu, 0.009 mg kg−1 for Mo, and 0.002 mg kg−1 for Pb. The precision ranged from 7.3% to 7.8%, 5.1% to 6.3%, 2.5% to 3.8%, 2.8% to 3.4%, and 6.2% to 7.3% for Al, Cd, Cu, Mo, and Pb, respectively. The accuracy of the method was evaluated through recovery tests, which ranged from 92.2% for Cd to 107.2% for Al. Cadmium concentrations in analyzed samples are below the limit allowed by Brazilian legislation (0.01 mg kg−1). However, two samples presented Pb concentration (samples 4 and 5) above the allowed limit (0.01 mg kg−1). Furthermore, all samples analyzed in this work showed relatively considerable quantities of Al (0.72–1.66 mg kg−1), and the concentrations of Cu (samples 3 and 4) and Mo (samples 1 and 5) were obtained were higher than those presented by the manufacturers. The proposed methods for the quantitative determination of the analytes of interest by HR-CS GFAAS after extraction induced by emulsion breaking in foods for enteral nutrition of chronic renal patients proved to be simple, fast, and efficient.

Determination of Silver in Environmental Samples by High-resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry after Preconcentration on Bentonite

Determination of Silver in Environmental Samples by High-resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry after Preconcentration on Bentonite

Assessment of palladium nanoparticles as chemical modifier for lead determination in leached extracts from petroleum waste by high-resolution continuum source atomic absorption spectrometry

ABSTRACT Palladium nanoparticles were evaluated as a potential chemical modifier for lead determination by high-resolution continuum source graphite furnace atomic absorption spectrometry. Hydrophilic palladium nanocubes and palladium nanospheres were synthesised with sizes varying from 3 to 22 nm. Positive effects in terms of sensitivity and thermal stability upon the use of palladium nanoparticles were observed, especially using the 3 nm spherical-shaped. The mass of modifier influenced the thermal stability and relative signal intensity of the analyte, although the effectiveness of the modifier appeared to be suppressed to an important extent in the presence of matrix components of the leached extracts obtained from petroleum wastes. The optimised pyrolysis and atomisation temperatures were, respectively, 800 °C and 2300 °C, using 200 ng of 3 nm palladium nanoparticles. The limit of detection (4 µg L−1) and the precision (better than 18 %) were considered satisfactory for the proposed analysis. The method accuracy, evaluated by recovery tests and by comparison with the results obtained using inductively coupled plasma mass spectrometry, was proven adequate to enable the determination of Pb in leached extracts from petroleum waste. The method was successfully applied to determine lead in leached extracts obtained from oily sludge and drill cuttings and the obtained concentrations ranged from <13 to 354.4 µg L−1.

Emulsion breaking-induced extraction of Cd and Pb from oily dietary supplements followed by graphite furnace atomic absorption spectrometry detection

A method is described for the determination of cadmium (Cd) and lead (Pb) in oily dietary supplements using extraction induced by emulsion breaking (EIEB) and high-resolution continuum-source graphite furnace atomic absorption spectrometry (HR-CS GFAAS). The method is based on the formation of a water-in-oil emulsion by the addition of an extractor solution consisting of 5 % (w/v) Triton X-100% and 15 % (v/v) hydrochloric acid (HCl) to the sample of oil diluted with 1.5 mL of toluene and the breakage of this emulsion by centrifugation (4000 rpm for 5 min). Two well-defined phases were formed and the acid aqueous phase containing extracted Cd and Pb ions was analyzed by HR-CS GFAAS. Different parameters that influence the extraction efficiency of Cd and Pb were optimized univariately. The detection limits were 3.32 μg kg−1 for Pb and 1.51 μg kg−1 for Cd. A matrix-based calibration method was applied to compensate for the interference caused by the matrix effects. The Cd concentration in the samples ranged from 8.81 to 9.35 μg kg−1 and the highest concentration of Pb was 19.91 μg kg−1. The proposed preparation of sample through extraction by breaking emulsions of oily dietary supplements proved to be a simple and efficient strategy to determine the amount of Pb and Cd by HR-CS GFAAS.

Use of slow atomization ramp in high resolution continuum source graphite furnace atomic absorption spectrometry for the simultaneous determination of Cd and Ni in slurry powdered chocolate samples

A methodology for simultaneous (not sequential) determination of Cd and Ni in powder chocolate samples by high-resolution continuum source graphite furnace atomic absorption spectroscopy (HR–CS–GF-AAS) and slurry sample analysis was developed. Acid digestion of the samples was not necessary, considering the high total fat content of this type of matrix (above 10 %), and no apparent deterioration of the graphite tubes was even observed once these samples were subjected to analysis. Despite the volatilities of both elements are quite different, simultaneous quantification was achieved using a slow heating ramp atomization, covering a convenient and wide temperature gradient for Cd volatilization at low temperatures and subsequent atomization of Ni at elevated temperatures, using the same heating program without an apparent change in sensitivity. This slow heating ramp was essayed between 200 and 1500 °C·s−1 and optimized at 400 °C·s−1, achieving the simultaneous measuring of Cd in the principal line (228.8018 nm) and using a secondary for Ni (228.9984 nm). No stop events for sequential changes in wavelength or temperature additional steps were involved in the method and molecular spectral interferences overlapping the analyte signals were corrected appropriately by a pragmatic strategy taking advantage of the fine structure signals adjacent to analyte signals within the same spectrum recorded. Palladium matrix modifier and aqueous standards were used for the calibration and determination of both elements in the samples. The method accuracy was successfully confirmed using a reference material (NIST SRM 1573a). An improvement in the sensitivity of Ni was found using a greater number of pixels for signal integration, central and five adjacent pixels (CP ± 5), while a lengthening of the linear range of Cd was obtained by using an attenuated signal (±2) or using only one pixel (CP). The limits of detection were 0.027 μg g−1 and 0.22 μg g−1 for Cd and Ni respectively by this simple methodology using aqueous standards for calibration and the simultaneous determination of both elements in the same measurement. The respective limits of quantification for Cd and Ni were 0.090 and 0.72 μg g−1 and the relative standard deviations in samples (n = 5) were about 4–20% and 0.3–11% for Cd and Ni respectively. The optimized method was used for the determination of both elements in real samples purchased from retail supermarkets finding variable concentrations between 0.5 and 5.7 μg g−1 for Cd and 2.1–10.9 μg g−1 for Ni, comparable to levels reported in the literature referred to elsewhere in the world.

Multielement determination of metals in edible seeds by HR-CS GF AAS and direct analysis

This work reports, for the first time, the multielement determination of Cd, Ni and Fe concentrations in edible seeds via high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS), using direct solid sample analysis. First, Cd (228.802 nm) concentration was determined using 400 and 1600 °C as pyrolysis and atomisation temperatures, respectively. In sequence, from the same sample aliquot, Ni (232.003 nm) and Fe (232.036 nm) concentrations were determined using 2500 °C as the atomisation temperature. A combination of Pd/Mg and H2O2 was used as a chemical modifier to improve the precision and overcome smoke interferences. Multielement aqueous standard solutions were used for calibration, and the detection limits were 3.1 µg kg−1 for Cd, 0.062 mg kg−1 for Ni and 3.4 mg kg−1 for Fe. The trueness was proven by analysing a standard reference material of Tomato Leaves (NIST SRM 1573a). The following concentration ranges were found in the samples: 39–254 µg kg−1 for Cd; 1.1–8.0 mg kg−1 for Ni; and 38–147 mg kg−1 for Fe. The Cd contents in with-shell pumpkin and in roasted and raw sunflower seed samples were above the maximum acceptable Cd level in cereals, as established by the Codex Alimentarius Commission of 100 µg kg−1.

Direct solid sampling of biological species for the rapid determination of selenium by high-resolution continuum source graphite furnace atomic absorption spectrometry

A direct solid sampling method based on high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS) for the determination of selenium (Se) in biological tissues was optimized. The main analytical line of Se at 196.0267 nm was used to carry out all HR-CS AAS measurements. Different chemical modifiers were evaluated to prevent the loss of Se during the application of the GFAAS temperature program and avoid the interferences due to the presence of phosphorus compounds in sample matrix. The best results were achieved using ruthenium coated platforms and a palladium nanoparticle suspension (Pd NP) as co-injected modifier. Calibration was performed using aqueous standard solutions of Se(IV). For solid sampling, the optimal range of sample mass was between 0.2 and 0.8 mg. The limit of detection (LOD) was 0.06 ng (0.075 μg g−1 using a sample mass of 0.8 mg). The developed solid sampling HR-CS GFAAS method was used for Se determination in two certified reference materials of dogfish tissues and lyophilized and powdered real samples of fish tissues and chicken liver. The precision obtained in these analyses, expressed as relative standard deviation (RSD), was between 5.5 and 8.6% (n = 6). For validation purposes, the results obtained by the solid sampling HR-CS GFAAS method were compared with those found performing the analysis by HR-CS hydride generation AAS (HR-CS HGAAS) after microwave acid digestion of the samples. The Se concentrations obtained for both methods agreed at a 95% confidence level (Student's t-test), indicating the suitability of the proposed solid sampling HR-CS GFAAS method to determine Se in biological samples.

General Applicability of High-Resolution Continuum-Source Graphite Furnace Molecular Absorption Spectrometry to the Quantification of Oligopeptides Using the Example of Glutathione

This communication introduces the first-time application of high-resolution continuum-source molecular absorption spectrometry (HR CS MAS) for the quantification of a peptide. The graphite furnace technique was employed and the tripeptide glutathione (GSH) served as a model compound. Based on measuring sulfur in terms of carbon monosulfide (CS), a method was elaborated to analyze aqueous solutions of GSH. The most prominent wavelength of the CS molecule occurred at 258.0560 nm and was adduced for monitoring. The methodological development covered the optimization of the pyrolysis and vaporization temperatures. These were found optimally to be 250 °C and 2250 °C, respectively. Moreover, the effect of modifiers (zirconium, calcium, magnesium, palladium) on the absorption signals was investigated. The best results were obtained after permanent coating of the graphite tube with zirconium (total amount of 400 μg) and adding a combination of palladium (10 µL, 10 g L−1) and calcium (2 µL, 1 g L−1) as a chemical modifier to the probes (10 µL). Aqueous standard samples of GSH were used for the calibration. It showed a linear range of 2.5–100 µg mL−1 sulfur contained in GSH with a correlation coefficient R2 &gt; 0.997. The developed method exhibited a limit of detection (LOD) and quantification (LOQ) of 2.1 µg mL−1 and 4.3 µg mL−1 sulfur, respectively. The characteristic mass accounted for 5.9 ng sulfur. The method confirmed the general suitability of MAS for the analysis of an oligopeptide. Thus, this study serves as groundwork for further development in order to extend the application of classical atomic absorption spectrometry (AAS).

Determination of Cu and Mn in Seawater by High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry

The conditions for the determination of copper and manganese in seawater by high-resolution continuum-source graphite furnace atomic absorption spectrometry (HR-CS GFAAS) were optimized. The analytical properties were compared with those of low-resolution line source GFAAS (LR-LS GFAAS). The metrological characteristics were estimated considering the dilution of the sample and optimization of the temperature program of the electrothermal atomizer. Using HR-CS GFAAS, the elements were determined in undiluted samples, while LR-LS GFAAS allows the determination only at double dilution. The lower limits of determined Cu concentrations almost coincided for both versions of GFAAS. For manganese, the limits of detection and quantification were significantly lower for HR-CS GFAAS. Calibration curves were plotted using standard solutions. The proposed scheme was tested on water samples from the Sea of Okhotsk by standard addition. The detection limits (LODs) were 0.6 µg L−1 for copper and 0.07 µg L−1 for manganese by HR-CS GFAAS and 0.5 µg L−1 for copper and 0.13 µg L−1 for manganese by LR-LS GFAAS.

Mineral profile of cricket powders, some edible insect species and their implication for gastronomy

Entomophagy is proclaimed as a sustainable nutritional strategy due to the high protein content in edible insects. As it turns out, it may also represent an effective tool for increasing dietary intake of nutrients that are frequently deficient. Cricket powder (CP) appears to be the simplest way. The objectives of this work were to determine the contents of fourteen minerals in CPs and in insect species namely, house cricket, yellow mealworm, desert locust, and superworm. To assess these insect species as sources of minerals with respect to the dietary recommended values (DRV) for some minerals, and to determine mineral enrichment level of some recipes with using CP. Samples were analyzed by means of high-resolution continuum source graphite furnace atomic absorption spectrometry and flame atomic absorption/emission spectrometry. These insect species can be considered as a uniform source of Fe. The species of house cricket, yellow mealworm, and desert locust would provide more than the DRV for Zn, Cu, and P. Replacing 10 % of the wheat flour with CP in bread and pasta recipes increases Zn content by 92–107 %. Finally, the low Cd and Pb contents indicate that the consumption of the given insect species presents no risk.

Sequential and Simultaneous Determination of Cd, Fe and Ni in Toothpastes Employing Slurry Sampling High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry

Here is reported an analytical method for the multielemental determination of Cd, Fe and Ni in toothpaste employing slurry sampling high-resolution continuum source electrothermal atomic absorption spectrometry (HR-CS ET AAS). Using a single sample aliquot, Cd was determined at 228.802 nm, and, sequentially, Fe (232.036 nm) and Ni (232.003 nm) were simultaneously determined. Pyrolysis and atomization temperatures were 800 and 1500 °C for Cd, respectively. An atomization temperature of 2600 °C was used for Fe and Ni. A Pd and Mg mixture was used as the chemical modifier for standards and samples. The procedure for the slurry preparation was optimized using multivariate methodology with a multiple response function while employing a sample mass of about 250 mg. The optimized conditions were: 0.8 mol L−1 HNO3, 0.5% (m/v) Triton X-100 and a sonication time of 15 min. Using aqueous standards for the calibration, limits of detection and quantification were of 3.2 and 10.8 ng g−1 for Cd, 2.2 and 7.4 µg g−1 for Fe, and 0.044 and 0.148 µg g−1 for Ni. The precision estimated as relative standard deviation (n = 5) was 6.1% for Cd, 3.5% for Fe and 4.4% for Ni. The method accuracy was evaluated by standard addition and recovery tests and the recoveries varied from 93 to 114%. The method was applied for the analysis of five toothpaste samples of different brands. The concentrations ranged from 52.0 to 73.6 µg g−1 for Fe, and < 0.148 to 0.227 µg g−1 for Ni. For Cd, the concentrations were below the limit of detection.

High-Resolution Atomic Absorption Spectrometry Combined With Machine Learning Data Processing for Isotope Amount Ratio Analysis of Lithium.

An alternative method for lithium isotope amount ratio analysis based on a combination of high-resolution atomic absorption spectrometry and spectral data analysis by machine learning (ML) is proposed herein. It is based on the well-known isotope shift of approximately 15 pm for the electronic transition 22P←22S at around the wavelength of 670.8 nm, which can be measured by the state-of-the-art high-resolution continuum source graphite furnace atomic absorption spectrometry. For isotope amount ratio analysis, a scalable tree boosting ML algorithm (XGBoost) was employed and calibrated using a set of samples with 6Li isotope amount fractions, ranging from 0.06 to 0.99 mol mol-1, previously determined by a multicollector inductively coupled plasma mass spectrometer (MC-ICP-MS). The calibration ML model was validated with two certified reference materials (LSVEC and IRMM-016). The procedure was applied toward the isotope amount ratio determination of a set of stock chemicals (Li2CO3, LiNO3, LiCl, and LiOH) and a BAM candidate reference material NMC111 (LiNi1/3Mn1/3Co1/3O2), a Li-battery cathode material. The results of these determinations were compared with those obtained by MC-ICP-MS and found to be metrologically comparable and compatible. The residual bias was -1.8‰, and the precision obtained ranged from 1.9 to 6.2‰. This precision was sufficient to resolve naturally occurring variations, as demonstrated for samples ranging from approximately -3 to +15‰. To assess its suitability to technical applications, the NMC111 cathode candidate reference material was analyzed using high-resolution continuum source atomic absorption spectrometry with and without matrix purification. The results obtained were metrologically compatible with each other.