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1.
Food Chem ; 317: 126437, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32109660

RESUMO

SO2 is a type of additive widely used in the food processing industry as preservative and anti-browning, bleaching, or effective antibacterial agent. However, the SO2 residue can have adverse effects on human health. In this work, a low-temperature microplasma generated by dielectric barrier discharge was used for the direct, in situ excitation of the molecular emission of SO2 in food samples. The food samples were acidified and heated to release SO2 and a miniaturized charge-coupled device spectrometer recorded the characteristic emission line at 301.9 nm. The linear correlation coefficient of the method was greater than 0.99 in the range of 10 to 100 mg L-1. Moreover, the limit of detection was 0.01 mg L-1, with recoveries between 72% and 108% and relative standard deviations of 1.5%-7.6%. The method is simple, accurate, low-cost, involves miniaturized and compact equipment and is suitable for the determination of total SO2 in food samples.


Assuntos
Análise de Alimentos/instrumentação , Espectrofotometria Atômica/instrumentação , Dióxido de Enxofre/análise , Desenho de Equipamento , Aditivos Alimentares/análise , Análise de Alimentos/métodos , Limite de Detecção , Miniaturização , Espectrofotometria Atômica/métodos
2.
Artigo em Inglês | MEDLINE | ID: mdl-31905046

RESUMO

A method for the analysis of different species of antimony (Sb) that couples liquid chromatography with an inductively coupled plasma-optical emission spectrometry (LC-ICP-OES) system is presented. The method is simple and reliable to separate and quantify directly and simultaneously Sb(III) and Sb(V) in aqueous samples. The calibration curves showed high linearity at the three wavelengths tested. The limits of detection ranged from 24.9 to 32.3 µg/L for Sb(III) and from 36.2 to 46.0 µg/L for Sb(V), at the three wavelengths evaluated. The limit of detection for this method varied depending on the wavelength used. The lowest limit of quantification for Sb(V) (49.9 µg/L) and Sb(III) (80.7 µg/L) was obtained at a wavelength of 217.582 nm. The method sensitivity for Sb(V) was higher compared to Sb(III) at all the wavelengths considered. Samples containing different concentrations of Sb(III) and Sb(V) in three different matrices, i.e., water, basal culture medium, and anaerobic sludge plus basal medium, were analyzed. The coefficients of variation were low and ranged from 0.1 to 5.0 depending on the sample matrix. Recoveries of Sb(III) and Sb(V) were higher than 90% independently of the matrix analyzed and the wavelength used in the analysis.


Assuntos
Antimônio/análise , Espectrofotometria Atômica/métodos , Poluentes Químicos da Água/análise , Calibragem , Meios de Cultura/química , Limite de Detecção , Reprodutibilidade dos Testes , Esgotos/química , Água/química
3.
Environ Pollut ; 256: 113468, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31679880

RESUMO

The increasing content of platinum group metal particles emitted into the environment by car traffic is gradually attracting the attention of the scientific community. However, the methods for the determination of platinum group metals in environmental matrices are either costly or suffer from low sensitivity. To facilitate the use of less sensitive, but significantly cheaper, devices, the preconcentration of platinum group metals is employed. For platinum, a multitude of preconcentration approaches have been published. On the contrary, the preconcentration approaches for palladium are still rare. In this work, the development, optimization, and testing of a new approach is described; it is based on a preconcentration of palladium on octadecyl modified silica gel together with the complexing agent dimethylglyoxime, and it is then analyzed with the high-resolution continuum-source atomic absorption spectrometry. For comparison, a newly developed sorbent, QuadraSil™ TA, with a high affinity for platinum group metals was also tested. The preconcentraiton approach was tested on the lichen Hypogymnia physodes, which served as a bioindicator of palladium emissions. The case study site was a mid-sized city in central Europe: Brno, Czech Republic. The dry "bag" monitoring technique was used to collect the palladium near roads with a large span of traffic density. The developed analytical approach confirmed an increasing concentration of palladium with increasing exposure time and intensity of the traffic. Consequently, a simple relationship between the amount of bioaccumulated palladium and traffic density was established.


Assuntos
Monitoramento Ambiental , Poluentes Ambientais/análise , Líquens/química , Paládio/análise , Cidades , República Tcheca , Paládio/química , Platina/análise , Sílica Gel , Espectrofotometria Atômica/métodos
4.
Food Chem ; 302: 125336, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31419772

RESUMO

This study reports a stepwise optimization of switchable liquid-liquid microextraction (SLLME) for cobalt determination by flame atomic absorption spectrometry (FAAS) coupled with a slotted quartz tube (SQT). The main purpose of this study was to develop an accurate and sensitive analytical method for cobalt. Extraction method was used to separate and preconcentrate cobalt from sage tea and vitamin B12 samples after complexing with a Schiff base ligand. 107.7 folds enhancement in detection power under the optimum conditions was recorded with respect to direct FAAS. This enhancement correlated to 3.1 µg/L limit of detection and 10 µg/L limit of quantification. The SLLME-SQT-FAAS method was linear over a broad concentration range and low %RSD values established high precision for the method. Appreciable percent recovery results (94-108%) obtained from spiked sage sample and from cobalamin also validated the accuracy of the method.


Assuntos
Cobalto/análise , Microextração em Fase Líquida/métodos , Espectrofotometria Atômica/métodos , Chás de Ervas/análise , Vitamina B 12/análise , Limite de Detecção , Quartzo , Reprodutibilidade dos Testes , Salvia officinalis/química , Bases de Schiff/química , Espectrofotometria Atômica/instrumentação , Vitamina B 12/química
5.
Food Chem ; 303: 125396, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31446365

RESUMO

This study describes the determination of lead at trace levels by slotted quartz tube flame atomic absorption spectrophotometry (SQT-FAAS) after preconcentration by the help of stearic acid coated magnetic nanoparticle (SAC-MNPs) based sonication assisted dispersive solid phase extraction (SA-DSPE). SAC-MNPs were used due to their easy separation advantages by the application of external magnetic field. All extraction parameters were optimized by response surface methodology based experimental design. The experimented data was evaluated by the analysis of variance. Under the optimum conditions, about 31 folds enhancement in detection power was obtained over the conventional FAAS. The recovery results obtained for samples spiked at 60 and 120 ng mL-1 were 106.6 and 102.6%, respectively, validating the method as accurate and applicable to the red pepper matrix. The percent relative standard deviations of the results were under 5.0% even at low concentrations that established high precision for replicate extractions and instrumental readings.


Assuntos
Capsicum/química , Chumbo/análise , Chumbo/isolamento & purificação , Microextração em Fase Líquida/métodos , Magnetismo/métodos , Extração em Fase Sólida/métodos , Espectrofotometria Atômica/métodos , Contaminação de Alimentos/análise , Frutas/química , Magnetismo/instrumentação , Nanopartículas de Magnetita/química , Quartzo/química , Sensibilidade e Especificidade , Sonicação , Ácidos Esteáricos/química
6.
Food Chem ; 306: 125638, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31606632

RESUMO

A green and innovative eutectic solvent based extraction method was proposed for the determination of trace level vanadium in water and food samples by graphite furnace atomic absorption spectrometry. In this extraction technique magnetic stirrer was used for preparation of eutectic solvent by mixing of zinc chloride and acetamide at different molar ratios. Extraction capability of eutectic solvent was increased by adding a non ionic surfactant (Triton X-114) to enhanced phase transfer ratio, to significantly increase the recovery of hydrophobic complex of vanadium with ammonium pyrrolidine dithiocarbamate. A multivariate technique was applied to evaluate the important extraction parameters, which plays important role for optimum recovery of the targeted analyte by proposed extraction method. Multivariate techniques such as (factorial design and central composite design) were applied to screening out the most significant extraction parameters and optimized them. Under optimized extraction conditions, limit of detection and enhancement factor were found to be 0.01 µg L-1 and 64.6, respectively. The relative standard deviation for the determination of trace level vanadium at 0.32 µg L-1 concentration, was achieved to be <3.0% (n = 10). Validity and accuracy of the proposed extraction method was checked by analysis of certified reference materials of Canadian lake water and tomato leaves with % age recovery >98%. The eutectic solvent extraction method was successfully applied for the determination of the trace level vanadium in real water samples of different sources and acid digested food samples, collected from different locations of Tokat city, Turkey.


Assuntos
Alimentos , Vanádio/análise , Água/química , Canadá , Análise de Alimentos , Grafite/química , Magnetismo , Solventes/química , Espectrofotometria Atômica/métodos
7.
Food Chem ; 309: 125754, 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-31734006

RESUMO

The present work illustrates the potential of laser-induced breakdown spectroscopy (LIBS) for the direct analysis of liquid food products. The aim of the experiment was to predict calcium content in ready-to-feed infant formula. The analysis was performed by a LIBS system coupled to a liquid sample chamber with a rotatory wheel that presents the liquid to the laser beam as a thin film. Multivariate analysis with partial least squares regression (PLSR) was performed to correlate LIBS spectral data to reference calcium contents. The obtained PLSR model exhibited a good fit and linearity, as indicated by the coefficients of determination for calibration (Rc2) and cross-validation (Rcv2), with values of 0.96 and 0.89, respectively. The robustness of the calibration model was assessed by external validation showing a root-mean-square error of prediction of 6.45 mg 100 mL-1. These results demonstrated the potential of LIBS for real-time analysis of liquid food products.


Assuntos
Cálcio/análise , Fórmulas Infantis/análise , Lasers de Estado Sólido , Espectrofotometria Atômica/métodos , Cálcio/normas , Calibragem , Humanos , Lactente , Análise dos Mínimos Quadrados , Modelos Lineares , Reprodutibilidade dos Testes , Espectrofotometria Atômica/normas
8.
Chemosphere ; 239: 124788, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31521935

RESUMO

Digestion of biomass derived carbonaceous materials such as biochar (BC) can be challenging due to their high chemical recalcitrance and vast variations in composition. Reports on the development of specific sample digestion methods for such materials remain inadequate and thus require considerable attention. Nine different carbonaceous materials; slow-pyrolyzed tea-waste and king coconut BC produced at 300 °C, 500 °C and 700 °C, sludge waste BC produced at 700 °C, wet fast-pyrolyzed Douglas-Fir BC and steam activated coconut shell BC have been tested to evaluate a relatively fast and convenient open-vessel digestion method using seven digestion reagents including nitric acid (NA), fuming nitric acid (FNA), sulfuric acid (SA), NA/SA, FNA/SA, NA/H2O2 and SA/H2O2 mixtures. From the tested digestion reagents, SA/H2O2 mixture dissolved low temperature produced BC (LTBC) within 2 h with occasional shaking and no external heating. Except peroxide mixtures, the other reagents were used to evaluate microwave digestion (MWD) efficiency. Nitric acid mixture was capable of only completely digesting LTBC in the MWD procedure whereas FNA, NA/SA and FNA/SA mixtures resulted in the successful dissolution of all tested carbonaceous materials. Amongst them, FNA provided the least matrix effect in the quantification of the four metals tested using flame atomic absorption spectrophotometry. Tested recoveries for FNA were satisfactory as well. It was concluded that FNA is a preferable reagent for microwave digestion of BC.


Assuntos
Carvão Vegetal/química , Resíduos , Cocos , Indústria de Laticínios , Peróxido de Hidrogênio , Metais/análise , Micro-Ondas , Ácido Nítrico/química , Pirólise , Esgotos , Espectrofotometria Atômica/métodos , Ácidos Sulfúricos/química
9.
Environ Monit Assess ; 192(1): 61, 2019 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-31865447

RESUMO

Tellurium has been widely used in industrial processes and daily life products, and can cause serious health problems upon exposure. Therefore, determination of tellurium in real-life samples is very crucial. In this study, an accurate, environmentally friendly, and inexpensive analytical method was developed to determine trace levels of tellurium in water samples. To lower the detection limits, system parameters including flame type, acetylene flow rate, slotted quartz tube (T-SQT) height, and trapping period were optimized. Under the optimum conditions, the limit of detection (LOD) and quantification (LOQ) were calculated as 14.1 ng/mL and 47.1 ng/mL, respectively. For recovery studies, the optimized T-SQT-AT-FAAS method was applied to tap water samples to determine trace levels of tellurium and recovery results were found between 91.1 and 111.3%. Relative standard deviation value (%RSD) of the developed method was found to be less than 5.0% even for the lowest concentration in calibration plot, specifying good accuracy and high applicability of the method for water samples. Graphical abstract .


Assuntos
Água Potável/química , Monitoramento Ambiental/métodos , Espectrofotometria Atômica/métodos , Telúrio/análise , Poluentes Químicos da Água/análise , Água Potável/normas , Monitoramento Ambiental/instrumentação , Concentração de Íons de Hidrogênio , Limite de Detecção , Microextração em Fase Líquida/métodos
10.
Environ Monit Assess ; 191(11): 692, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31667640

RESUMO

In this study, a rapid and effective dispersive solid-phase microextraction (d-SPME) method was developed to preconcentrate Pd from aqueous extract of soil samples by slotted quartz tube-flame atomic absorption spectrometry (SQT-FAAS). The unique properties of magnetic nanoparticles (MNPs) were used to directly isolate Pd from the sample solutions without the need for complexation. Significant parameters of the extraction method such as magnetic nanoparticle type and amount, pH and amount of buffer solution, amount of eluent, and mixing type and period were optimized together with other instrumental parameters to boost the absorbance signal of Pd. An SQT was fitted onto the burner head to boost the interaction between Pd atoms and hollow cathode lamp radiation to enhance absorbance signals. The limit of detection (LOD) and limit of quantification (LOQ) values for Pd determined (d-SPME-MNP-SQT-FAAS) were 6.4 and 21.4 ng/mL, respectively. The percentage relative standard deviation of the developed method was calculated as 6.6%. The method was applied to soil samples taken from the campus area and spiked recovery experiments were performed to evaluate the method's accuracy/applicability. Satisfactory percent recovery results (90-101%) were obtained for different spiked concentrations and this proved the accuracy/applicability of the method.


Assuntos
Paládio/análise , Poluentes do Solo/análise , Monitoramento Ambiental/métodos , Limite de Detecção , Microextração em Fase Líquida/métodos , Magnetismo , Nanopartículas de Magnetita , Quartzo/química , Solo , Microextração em Fase Sólida , Espectrofotometria Atômica/métodos , Água/análise
11.
J Trace Elem Med Biol ; 56: 207-212, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31541895

RESUMO

Traceability of metal-glycinate-sulphate complexes (Metal-GLY) in feed requires specific analysis to differentiate complexes from inorganic forms. A previously described method focused on the quantification of Metal-GLY at one single concentration but not on the quantification of free metal ion forms. The objective of this work was to extend the method to quantify both Metal-GLY and free metal ion forms of various metals at low inclusion levels. A 50/50 w/w mix of corn flour and soybean meal was used as feed. Copper-glycinate(Cu-GLY), Manganese-glycinate (Mn-GLY) and Zinc-glycinate (Zn-GLY) complexes (provided by Pancosma SA) were used for in-feed inclusions. The feed metal background concentrations and species repartitions were assessed. Cu-GLY was spiked on feed at levels matching 5, 15 and 45 mg/kg, corresponding to metal concentrations of 1.2, 3.6 and 10.8 mg/kg. Mn-GLY and Zn-GLY were spiked at 15, 45 and 100 mg/kg, corresponding to 3.3, 9.9, 22 mg/kg Mn and 3.9, 11.7, 26mg/kg Zn, respectively. The water soluble fraction of un-supplemented feed contained 0.06 mg/kg Cu, 0.05 mg/kg Mn and 0.12 mg/kg Zn, with 69.5% of Cu, 33.2% of Mn and 24.3% of Zn being present under free metal ions but 30.4% of Cu being present under Cu-GLY, 66.82% of Mn and 75.7% of Zn being present under Mn-GLY and Zn-GLY, respectively. The supplemented feeds at the 3 tested doses, from the lowest to the highest inclusion levels, contained in total respectively: 1.1, 3.05 and 9.06 mg/kg Cu; 2.99, 8.9 and 18.2 mg/kg Mn; 3.72, 10.9 and 23.4 mg/kg Zn. The M-GLY species recovered by analysis within the different supplemented feeds ranged from 76.26 to 89.32% for Cu-GLY, form 94.5 to 98.51% for Mn-GLY and from 76.05 to 98.96% for Zn-GLY. These results showed that CE-ICP-MS technique can be used to quantify low doses and to measure metal-species repartition between Metal-GLY and free metal ions, when included in feeds. For the first time, this study highlighted that the raw materials used contain Metal-GLY compounds. This raises the question of the occurrence of these compounds within the different raw materials used in feed production that could dramatically affect the way to supplement minerals in animal feed.


Assuntos
Ração Animal/análise , Complexos de Coordenação/análise , Eletroforese Capilar/métodos , Glicina/análise , Metais/análise , Espectrofotometria Atômica/métodos , Sulfatos/análise , Animais
12.
Environ Sci Pollut Res Int ; 26(31): 31763-31769, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31485944

RESUMO

Psoriasis, a skin inflammatory disease, originates from dysregulated interactions of the immune system and environmental factors. In the present study, cadmium (Cd) and zinc (Zn) were analyzed in biological samples (blood and scalp hair) of smoker and nonsmoker males who have mild and severe psoriasis. The patients were evaluated according to criteria based on the standard clinical diagnosis and classified into mild and severe psoriasis groups using the Psoriasis Area Severity Index (PASI) score. Both elements were determined by atomic absorption spectrometry after matrix oxidation. In smoker psoriatic patients, the level of Cd in biological samples was significantly increased. The Zn was significantly decreased in smoker mild and severe psoriatic patients as related to nonsmokers' referents and patients. The resulted data indicated that the levels of Zn in smoker referents were about 5.0% lower than nonsmoker's referents. While the concentrations of Zn in blood samples of nonsmoker's mild and severe psoriatic patients have 17.8 to 33.3% lower than nonsmoker's referents. The results indicate that the level of Cd in blood samples of referent smokers has ≥ 25% than nonsmokers, whereas the psoriatic patients at different stages have two- to threefold higher Cd in both biological samples.


Assuntos
Cádmio/análise , Cabelo/química , Couro Cabeludo/química , Espectrofotometria Atômica/métodos , Zinco/análise , Feminino , Humanos , Masculino , não Fumantes , Fumantes
13.
J Chromatogr A ; 1607: 460393, 2019 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-31376982

RESUMO

Characterization of silver-associated proteins is important to elucidate underlined mechanisms of silver-containing materials against microbes. Gel electrophoresis based methods are the most popular and basic strategy for the analysis of biomolecules, i.e., proteins and nucleic acids. It solely provides molecular weights of analytes. Extending the method from molecular weight to elemental composition is highly desired when investigating metal-containing molecules. Herein, a gel electrophoresis based method combining native sodium dodecyl sulfate-polyacrylamide gel electrophoresis (native SDS-PAGE), fluorescent staining, and inductively coupled plasma mass spectrometry (ICP-MS) strategy was developed for separation and detection of silver-associated proteins. Two home-made silver-labeled proteins, carbonic anhydrase and ovalbumin, were used for validation of the strategy performance. Silver-associated proteins in Pseudomonas aeruginosa and Staphylococcus aureus treated with silver nanoparticles were further characterized by this method. Some well-known and new proteins were identified to associate to silver in both P. aeruginosa and S. aureus, demonstrating the feasibility of the developed strategy. In conclusion, the current study provides a convenient method for readily identification of silver-associated proteins in biological samples.


Assuntos
Proteínas de Bactérias/metabolismo , Eletroforese em Gel de Poliacrilamida/métodos , Espectrometria de Massas/métodos , Nanopartículas Metálicas/química , Pseudomonas aeruginosa/metabolismo , Prata/química , Espectrofotometria Atômica/métodos , Staphylococcus aureus/metabolismo , Proteínas de Bactérias/química , Anidrases Carbônicas/metabolismo , Fluorescência , Peso Molecular , Ovalbumina/metabolismo , Proteínas de Prata
14.
Nutr. hosp ; 36(4): 753-757, jul.-ago. 2019. tab, ilus
Artigo em Espanhol | IBECS | ID: ibc-184696

RESUMO

Introducción: durante la infusión de una nutrición parenteral sin lípidos se observó un precipitado negro en el filtro. Hay hallazgos similares publicados en los que se han detectado cobre y azufre (proveniente de la cisteína) en la composición del precipitado. Objetivo: comprobar que la cisteína y el cobre intervienen en la formación del precipitado. Métodos: se tomaron muestras de la solución de nutrición parenteral antes y después de su paso por el filtro. Se analizaron en ambas muestras las concentraciones de aminoácidos mediante cromatografía de intercambio iónico y derivatización post-columna con ninhidrina en un equipo Biochrom 30 y las de cobre mediante espectrometría de absorción atómica en un equipo PerkinElmer AAnalyst(TM) 200. Resultados: las concentraciones de cisteína y cobre en la solución disminuyeron en un 29,3% y 75,9%, respectivamente. Conclusiones: la disminución de las concentraciones de cisteína y cobre en la solución filtrada sugieren que ambos están involucrados en la formación del precipitado negro observado en el filtro


Introduction: a black precipitate was observed in the filter during the infusion of a parenteral nutrition without lipids. There are similar findings published in which copper and sulphur (from cysteine) were found in the composition of the precipitate. Objective: to determine if copper and cysteine are involved in the formation of the precipitate. Methods: samples of the parenteral nutrition solution were taken before and after its passage through the filter. Amino acids concentrations were analysed in both samples by ion exchange chromatography and post-column derivatization with ninhydrin in a Biochrom 30 device. Copper concentrations were measured by atomic absorption spectrometry in a PerkinElmer AAnalyst(TM) 200 device. Results: a decrease in cysteine concentration of 29.3% was found. The concentration of copper decreased by 75.9%. Conclusions: the decrease in the concentrations of cysteine and copper in the filtered solution suggest that both are involved in the formation of the black precipitate observed in the filter


Assuntos
Humanos , Nutrição Parenteral/métodos , Soluções de Nutrição Parenteral/química , Precipitação Química , Aminoácidos/química , Nutrição Parenteral/normas , Cobre/química , Cisteína/química , Enxofre/química , Espectrofotometria Atômica/métodos , Filtração/métodos
15.
Analyst ; 144(17): 5117-5126, 2019 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-31309214

RESUMO

Many species of Dalbergia are prized hardwoods, generally referred to as 'Rosewood,' and used in high-end products due to their distinctive hue and scent. Despite more than 58 species of Dalbergia being listed as endangered in Appendix 1 of The Convention on International Trade in Endangered Species of Fauna and Flora (CITES), the illegal logging and trade of this timber is ongoing. In this work, a handheld laser induced breakdown spectrometer (LIBS) was used to analyze seven Dalbergia species and two other exotic hardwood species to evaluate the ability of handheld LIBS for rapid classification of Dalbergia in the field. The KNN model of the classification presented 80% to 90% sensitivity for discriminating between Dalbergia species in the training set. PLS-DA models were based on a binary decision tree structure. Cumulatively, the PLS-DA decision tree model showed greater than 97% sensitivity and 99% selectivity for prediction of Dalbergia species included in the training set. The data presented in the following study are promising for the use of handheld LIBS devices and both KNN and PLS-DA models for applications in customs screenings at the port of entry of hard woods, among others.


Assuntos
Dalbergia/classificação , Madeira/química , Árvores de Decisões , Análise Discriminante , Espécies em Perigo de Extinção , Análise dos Mínimos Quadrados , Espectrofotometria Atômica/instrumentação , Espectrofotometria Atômica/métodos
16.
Food Chem ; 298: 125084, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31260980

RESUMO

A method for simultaneous determination of cadmium and iron in cereal flakes using high-resolution continuum source graphite furnace atomic absorption spectrometry is presented. Sample digest is introduced into the graphite furnace together with Pd/Mg(NO3)2 modifier. The primary absorption line of cadmium and adjacent secondary line of iron are used for the determination. Atomization is performed as a two-step process in order to meet ideal conditions for both elements. Interference produced by molecular absorption of PO molecular bands is suppressed by correction model using least squares background correction. Using the proposed method, levels of cadmium and iron were determined in different kinds of cereal flakes, where both elements are of great interest. Working range (0.01-2 µg L-1 for Cd and 10-500 µg L-1 for Fe) was suitable for the determination of analytes in samples. The method is fast, robust, and may be routinely used routinely in the analysis of foodstuffs.


Assuntos
Cádmio/análise , Grão Comestível/química , Análise de Alimentos/métodos , Ferro/análise , Espectrofotometria Atômica/métodos , Grafite/química
17.
Food Chem ; 300: 125180, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31325753

RESUMO

An isonicotinic acid hydrazide (INAH) chemically modified fumed silica, as a novel adsorbent, was designed for the preconcentration and determination of Hg (II) ions in fish samples via the solid phase extraction followed by the hydride generation atomic absorption spectrometry (HG-AAS). In this work, the efficiency of the synthesized adsorbent was investigated to determine its ability for the extraction of the Hg (II) ions from the aqueous solutions. The extraction efficiency was investigated by optimizing of different experimental conditions, such as pH, sample volume, flow rate, adsorbent dosage, and eluent type. Under the optimal conditions, a linear calibration curve for the solid phase extraction method was obtained in the range of between 0.12 and 16.5 µg L-1. The obtained detection limit and preconcentration factor were 0.018 µg L-1 and 25, respectively (RSD > 3%). The proposed optimized method was successfully applied to fish samples.


Assuntos
Produtos Pesqueiros/análise , Mercúrio/análise , Nanopartículas/química , Extração em Fase Sólida/métodos , Espectrofotometria Atômica/métodos , Adsorção , Animais , Contaminação de Alimentos/análise , Concentração de Íons de Hidrogênio , Limite de Detecção , Mercúrio/isolamento & purificação , Dióxido de Silício/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/isolamento & purificação
18.
Food Chem ; 293: 378-386, 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31151625

RESUMO

Considering the negative impacts on human health and the environment, determinations of arsenic (As) and antimony (Sb), is of unquestionable importance. The present study describes the development of innovative and practical deep eutectic solvent (DES) based vortex assisted microextraction (DES-VAME) method for preconcentration of As and Sb from environmental waters, honey and rice prior to analysis by hydride generation-atomic absorption spectrometry (HG-AAS). The use of As(III) and Sb(III) in presence of dithizone at pH 10.5 by means of donor-acceptor mechanism were decided as analytes. Total As and Sb were determined after reduction process. The analytical properties obtained following optimization were as follows. Limit of detection (LOD), precision (as RSD%), recoveries and enhancement factor for As and Sb were calculated as 7.5 ng L-1/15.6 ng L-1, 2.1% /2.7%, 93.5%/96.2% and 104/85, respectively. Following validation with certified reference material, the method was successfully applied to the analysis of real samples.


Assuntos
Antimônio/isolamento & purificação , Arsênico/isolamento & purificação , Análise de Alimentos/métodos , Microextração em Fase Líquida/métodos , Antimônio/análise , Arsênico/análise , Análise de Alimentos/instrumentação , Contaminação de Alimentos/análise , Mel/análise , Concentração de Íons de Hidrogênio , Limite de Detecção , Microextração em Fase Líquida/instrumentação , Oryza/química , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Solventes/química , Espectrofotometria Atômica/métodos , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/isolamento & purificação
19.
Environ Pollut ; 252(Pt A): 637-643, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31185352

RESUMO

Inductively coupled plasma - mass spectrometry (ICP-MS) analysis of airborne particulate bound mercury was carried out utilizing a high sulfur containing organic compound as a preservation agent to limit the negative bias that affects the determination of low levels of mercury. Between 600% and 1000% more Hg was detected with the use of the additive, lithium tetrathiafulvalene carboxylate (LiCTTF), during the microwave assisted acid digestion sample processing step without influencing the determination of other trace elements. The average Hg concentration was 0.05 ng m-3 and 0.4 ng m-3 in the absence and presence of LiCTTF, respectively. Stabilization of the mercury ions with the preservation agent resulted in higher precision for ICP-MS measurements with relative standard deviation (RSD) values ranging from 1.07% to 4.36%. The results obtained in this study emphasize the necessity of using a preservation agent in the atomic spectroscopic determination of mercury to prevent losses and is especially critical in low-level analyses such as those routinely performed in environmental mercury pollution trend assessments.


Assuntos
Monitoramento Ambiental , Mercúrio/análise , Material Particulado/análise , Espectrometria de Massas/métodos , Micro-Ondas , Espectrofotometria Atômica/métodos , Oligoelementos/análise
20.
Talanta ; 203: 210-219, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31202328

RESUMO

A magnetic functionalized bio-sorbent based on aptamer was designed for the selective separation of ultra-trace Pb2+, shortly termed as Fe3O4@Au@DNA. Pb(II) specific aptamer attached to the magnetic solid substrate served as affinity probe to capture and separate trace lead. Oligonucleotides with a polyA block were employed for the immobilization on the surface of AuNPs, with adenine sequences (polyA) as the part of effective anchoring block. The prepared Fe3O4@Au@DNA composites were characterized by FT-IR, SEM and XPS. The binding of lead on Fe3O4@Au@DNA composites surface was pH-dependent, the adsorption follows Langmuir model, and the adsorption dynamic fits the pseudo-second-order kinetics model. Procedure for lead separation and preconcentration was explored and combined with detection of graphite furnace atomic absorption spectrometry (GFAAS). Under the optimum condition, an enrichment factor of 17.73 was obtained with a sample volume of 1.0 mL. The limit of detection (LOD) was 57 ng L-1 along with a relative standard deviation (RSD) of 2.06 (n = 9). The procedure was further validated by a certified reference material GBW08608 and several environmental and blood samples.


Assuntos
Aptâmeros de Nucleotídeos/química , DNA/química , Chumbo/sangue , Nanopartículas de Magnetita/química , Espectrofotometria Atômica/métodos , Poluentes Químicos da Água/análise , Adsorção , Ouro/química , Humanos , Lagos/análise , Chumbo/química , Limite de Detecção , Concentração Osmolar , Poluentes Químicos da Água/química
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