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1.
Anal Bioanal Chem ; 416(11): 2641-2656, 2024 May.
Article in English | MEDLINE | ID: mdl-38243115

ABSTRACT

In the last decades, the determination of trace elements in biological materials has emerged as an important area of study because of its relevance to human health and the environment. Inductively coupled plasma mass spectrometry (ICP-MS) has proven to be a powerful tool for trace element analysis, owing to its high sensitivity and ability to determine several elements in a single measurement. However, given the complex nature of biological matrices and the presence of elements, most of them at ultratrace levels, it becomes crucial to complement ICP-MS with preconcentration techniques to increase the sensitivity and selectivity of analytical methods. This article presents an exhaustive overview of liquid- and solid-phase preconcentration techniques used in combination with ICP-MS for trace element determination in different biological samples from 2000 to the present. An in-depth discussion of the advances on the application of state-of-the-art solvents and materials in trace element extraction and preconcentration is presented. Special attention is given to different strategies for elemental speciation analysis, employing both chromatographic and non-chromatographic techniques. The role of automation in these methodologies is also described. Finally, future trends and challenges related to this topic are discussed.


Subject(s)
Trace Elements , Humans , Trace Elements/analysis , Mass Spectrometry/methods , Spectrum Analysis , Solvents
2.
Talanta ; 269: 125451, 2024 Mar 01.
Article in English | MEDLINE | ID: mdl-38048680

ABSTRACT

Metals and metalloids have different effects on human health even at trace levels. Some of them are essential for living organisms while others can be toxic. Therefore, the determination of trace elements in food and beverage is highly important to understand their impact in human health. A new generation of solvents named deep eutectic solvents (DES) has emerged as a green alternative for trace element analysis, owing to their low toxicity, biodegradability, and high extraction capacity. In recent years, the application of DES in extraction techniques for trace element analysis in food and beverage samples has increased significantly. This review summarizes recent advances and challenges on the application of DES to develop microextraction techniques useful for the analysis of samples with complex matrices. The importance of the use of biodegradable substances instead of classic organic solvents, which are toxic, volatile, and flammable in methods for elemental analysis with a positive environmental impact is also highlighted. Finally, conclusions and future challenges arising from the use of DES in microextraction techniques are discussed.


Subject(s)
Liquid Phase Microextraction , Trace Elements , Humans , Deep Eutectic Solvents , Liquid Phase Microextraction/methods , Limit of Detection , Beverages , Solvents
3.
Anal Bioanal Chem ; 415(22): 5475-5486, 2023 Sep.
Article in English | MEDLINE | ID: mdl-37394522

ABSTRACT

A new hybrid bionanomaterial composed of graphene oxide (GO) and Spirulina maxima (SM) algae was synthesized and applied to develop a preconcentration method based on the dispersive micro-solid phase extraction (D-µ-SPE) technique for the determination of Pb in water and infant beverages. In this work, Pb(II) was extracted with 3 mg of the hybrid bionanomaterial (GO@SM) followed by a back-extraction step using 500 µL of 0.6 mol L-1 HCl. Then, a 1.5 × 10-3 mol L-1 dithizone solution was added to the sample containing the analyte to form a purplish red-colored complex for its detection by UV-Vis spectrophotometry at 553 nm. An extraction efficiency of 98% was obtained after optimization of experimental variables such as GO@SM mass, pH, sample volume, type, and time of agitation. A detection limit of 1 µg L-1 and a relative standard deviation of 3.5% (at 5 µg L-1 Pb(II), n = 10) were achieved. The calibration linear range was obtained between 3.3 and 95 µg L-1 Pb(II). The proposed method was successfully applied for the preconcentration and determination of Pb(II) in infant beverages. Finally, the greenness degree of the D-µ-SPE method was evaluated using the Analytical GREEnness calculator (AGREE), obtaining a score of 0.62.


Subject(s)
Spirulina , Water , Humans , Lead , Solid Phase Extraction/methods , Plants , Beverages
4.
Anal Chim Acta ; 1232: 340422, 2022 Nov 01.
Article in English | MEDLINE | ID: mdl-36257729

ABSTRACT

Here we report the use of graphene quantum dots (GQDs), obtained from 3D graphene foam, functionalized with 8-hydroxyquinoline (8-HQ) for the sensitive and selective detection of Hg2+ via front-face fluorescence. The great surface area and active groups within the GQDs permitted the functionalization with 8-HQ to increase their selectivity toward the analyte of interest. The fluorescence probe follows the Stern-Volmer model, yielding a direct relationship between the degree of quenching and the concentration of the analyte. Diverse parameters, including the pH and the use of masking agents, were optimized in order to improve the selectivity toward Hg2+ down to a limit of detection of 2.4 nmol L-1. It is hereby demonstrated that the functionalized GQDs work perfectly fine under adverse conditions such as acidic pH and in the presence of a large number of cationic and anionic interferences for the detection of Hg2+ in real samples. Parallel measurements using cold vapor atomic fluorescence spectrometry also demonstrated an excellent correlation with the front-face fluorescence method applied here for real samples including tap, river, underground, and dam waters.


Subject(s)
Graphite , Mercury , Quantum Dots , Quantum Dots/chemistry , Graphite/chemistry , Mercury/analysis , Spectrometry, Fluorescence/methods , Oxyquinoline
5.
Article in English | MEDLINE | ID: mdl-34831893

ABSTRACT

Speciation analysis is a key aspect of modern analytical chemistry, as the toxicity, environmental mobility, and bioavailability of elemental analytes are known to depend strongly on an element's chemical species. Henceforth, great efforts have been made in recent years to develop methods that allow not only the determination of elements as a whole, but also each of its separate species. Environmental analytical chemistry has not ignored this trend, and this review aims to summarize the latest methods and techniques developed with this purpose. From the perspective of each relevant element and highlighting the importance of their speciation analysis, different sample treatment methods are introduced and described, with the spotlight on the use of modern nanomaterials and novel solvents in solid phase and liquid-liquid microextractions. In addition, an in-depth discussion of instrumental techniques aimed both at the separation and quantification of metal and metalloid species is presented, ranging from chromatographic separations to electro-chemical speciation analysis. Special emphasis is made throughout this work on the greenness of these developments, considering their alignment with the precepts of the Green Chemistry concept and critically reviewing their environmental impact.


Subject(s)
Metalloids , Chromatography, Gas , Environment , Solvents
6.
Article in English | MEDLINE | ID: mdl-34157936

ABSTRACT

Selenium (Se) is an essential micronutrient for humans. Garlic (Allium sativum L.) metabolises Se into important Se-amino acids like Se-methylselenocysteine (Se-MetSeCys), precursor of methylselenol, an active species for cancer prevention. Therefore, the Se accumulation and speciation in garlic were studied to evaluate their relations with growth stages and types of plant clones. Four garlic clones (Nieve INTA, Union FCA, Gostoso INTA and Rubí INTA) were fortified with a Se solution (169 g Se L-1). The association of Se to different molecular weight fractions was evaluated by size-exclusion chromatography coupled to inductively coupled plasma mass spectrometry (SEC-ICP-MS) detection. Also, anion exchange chromatography (AEC-ICP-MS) was used for the determination of Se-amino acids, while their identification was performed by ESI-MS/MS. The Se was incorporated into high (7-5 kDa) and low (2-4 kDa) molecular weight fractions. The presence of Se-MetSeCys was observed mostly. Se-MetSeCys increased in bulbs to a maximum value but increased, then decreased, in leaves and roots. The Se-organic species were mostly found in bulbs in the last growth stage. Garlic showed a significant ability to accumulate and metabolise Se, specially, the red clones (Gostoso INTA and Rubí INTA). Also, this work suggests that this plant may become an attractive source of Se-amino acids with important biological properties.


Subject(s)
Food Analysis , Food Contamination/analysis , Garlic/chemistry , Selenium/analysis , Garlic/growth & development , Garlic/metabolism , Humans , Mass Spectrometry , Selenium/metabolism
7.
Anal Methods ; 13(8): 1033-1042, 2021 03 04.
Article in English | MEDLINE | ID: mdl-33555281

ABSTRACT

Efficient separation and preconcentration of inorganic Sb species in different water samples were performed in this work by a novel dispersive liquid-liquid microextraction (DLLME) method based on the application of a magnetic ionic liquid (MIL) and electrothermal atomic absorption spectroscopy (ETAAS) detection. The Sb(iii) species was selectively extracted by complexation with ammonium diethyldithiophosphate (DDTP) and 45 µL of the MIL trihexyl(tetradecyl)phosphonium tetrachloroferrate ([P6,6,6,14]FeCl4) as extractant. Subsequently, a magnetic rod was applied for phase separation, introducing it directly into the sample solution, and the MIL phase was then diluted in chloroform. Afterwards, 15 µL of this solution was injected into the graphite furnace of ETAAS for Sb determination. A multivariate study was performed to obtain the optimal extraction conditions. Selective reduction of Sb(v) to Sb(iii) with 1% (w/v) KI before preconcentration was applied for total inorganic Sb determination and Sb(v) concentration was calculated by subtraction. The analytical performance of the method included extraction efficiencies of 98.0% for Sb(iii) and 92.6% for Sb(v), LOD of 0.02 µg L-1 for Sb(iii) and relative standard deviations of 3.1% for Sb(iii) and 3.5% for Sb(v) (at 6 µg L-1 Sb(iii) and Sb(v), n = 10). The calibration linear range was 0.08-20 µg L-1. The results showed that the proposed methodology was highly sensitive and selective for Sb speciation analysis in tap, dam, mineral, wetland, underground, rain and river water samples.

8.
Talanta ; 222: 121460, 2021 Jan 15.
Article in English | MEDLINE | ID: mdl-33167201

ABSTRACT

A novel on-line preconcentration and speciation analysis method for the simultaneous determination of inorganic Se and Te species is presented in this work. The methodology is based on the on-line formation of a hydrophobic ionic liquid (IL) directly in the liquid sample stream of a flow injection system, thus achieving an efficient and rapid extraction of the analytes complexed with ammonium pyrrolidine dithiocarbamate into the finely dispersed extractant droplets, that were then retained in a column filled with cotton. A full study of the chemical and hydrodynamical parameters was developed, including the right selection of the IL used as extractant and its concentration, pH, complexing reagent, sample and ion-exchange reagent volumes and column design. Additionally, a miniaturized external hydride generator was adapted to the spectrometer in order to increase the sensitivity of the atomic fluorescence measurements using only 250 µL of 5 mol L-1 HNO3 in methanol as eluent. The analytical figures of merit obtained for 15 mL of sample included sensitivity enhancement factors of 71, 70, 49 and 40 for Te(IV), Te(VI), Se(IV) and Se(VI), respectively, and limits of detection of 1.8 ng L-1 for both Te species, 2.6 ng L-1 for Se(IV) and 3.2 ng L-1 for Se(VI). After optimization, the method was successfully applied for the analysis of environmental samples: soils and sediments, as well as sea, river, underground and tap water.

9.
Molecules ; 26(1)2020 Dec 23.
Article in English | MEDLINE | ID: mdl-33374724

ABSTRACT

In this study, three magnetic ionic liquids (MILs) were investigated for extraction of four estrogens, i.e., estrone (E1), estradiol (E2), estriol (E3), and ethinylestradiol (EE2), from environmental water. The cation trihexyl(tetradecyl)phosphonium ([P66614]+), selected to confer hydrophobicity to the resulting MIL, was combined with tetrachloroferrate(III), ferricyanide, and dysprosium thiocyanate to yield ([P66614][FeCl4]), ([P66614]3[Fe(CN)6]), and ([P66614]5[Dy(SCN)8]), respectively. After evaluation of various strategies to develop a liquid-liquid microextraction technique based on synthesized MILs, we placed the MILs onto a magnetic stir bar and used them as extracting solvents. After extraction, the MIL-enriched phase was dissolved in methanol and injected into an HPLC-UV for qualitative and quantitative analysis. An experimental design was used to simultaneously evaluate the effect of select variables and optimization of extraction conditions to maximize the recovery of the analytes. Under optimum conditions, limits of detection were in the range of 0.2 (for E3 and E2) and 0.5 µg L-1 (for E1), and calibration curves exhibited linearity in the range of 1-1000 µg L-1 with correlation coefficients higher than 0.998. The percent relative standard deviation (RSD) was below 5.0%. Finally, this method was used to determine concentration of estrogens in real lake and sewage water samples.


Subject(s)
Estradiol/analysis , Estradiol/isolation & purification , Ionic Liquids/chemistry , Liquid Phase Microextraction/methods , Magnetics , Sewage/analysis , Water Pollutants, Chemical/analysis , Estrogens/analysis , Estrogens/isolation & purification , Sewage/chemistry , Water Pollutants, Chemical/chemistry
10.
Talanta ; 212: 120802, 2020 May 15.
Article in English | MEDLINE | ID: mdl-32113564

ABSTRACT

A simple, novel and highly sensitive ionic liquid-assisted cloud point extraction (IL-CPE) and preconcentration method was developed for the determination and speciation analysis of tellurium, using 1-octyl-3-methylimidazolium chloride as an additive for improving the extraction efficiency of Triton X-114. The Te(IV) species was complexed with ammonium pyrrolidine dithiocarbamate, extracted into the micellar IL/surfactant phase and then directly measured by electrothermal atomic absorption spectrometry (ETAAS). The total Te concentration was obtained after a pre-reduction step and Te(VI) concentration was calculated as the difference between total Te and Te(IV). Several parameters, including the type and concentration of IL and surfactant, time and temperature of the IL-CPE procedure and ETAAS conditions were thoroughly evaluated and optimized. In addition, the action mechanism of the IL on CPE was studied by fluorescence measurements using Laurdan as a polarity probe. The decrease in the internal polarity caused by the incorporation of the IL into the micelles was responsible for the improvement in the extraction efficiency. Under the optimized conditions, a sensitivity enhancement factor of 87 and an extraction efficiency of 90% were achieved. Limits of detection of 1.1 and 1.7 ng L-1 and relative standard deviations of 3.9% and 5.0% for Te(IV) and Te(VI), respectively, were obtained. The developed IL-CPE method was successfully applied for Te speciation analysis in matrices of different complexities, such as waters (tap, underground and seawater), soil and sediment.

11.
Talanta ; 210: 120614, 2020 Apr 01.
Article in English | MEDLINE | ID: mdl-31987172

ABSTRACT

A preconcentration method based on a novel hybrid sorption nanomaterial consisting in a 3D graphene-Ni foam functionalized with an ionic liquid (IL) was developed for Hg species determination. The capability of different phosphonium-ionic liquids (PILs) to functionalize the hybrid material and form ion-pairs with Hg(II) chlorocomplex was evaluated. A comparative study with PILs containing the trihexyl(tetradecyl)phosphonium cation but different anions (dicyanamide and decanoate) and trihexyl(tetradecyl)phosphonium chloride was performed. Inorganic Hg (InHg) species was selectively retained forming a chlorocomplex (HgCl42-) followed by its retention in a column filled with the IL-3D graphene-Ni foam material implemented in an on-line micro solid phase extraction system (µSPE). The elution of Hg from the column was performed with SnCl2, which was also used as reducing agent for subsequent detection by cold vapor generation atomic fluorescence spectrometry (CV-AFS). Organic mercury species (OrgHg) were not retained on the sorption material of the column. The effect of several parameters determining the efficiency of the preconcentration and detection system (sample loading and elution flow rate, sample volume, instrumental conditions, etc.) was investigated. A sensitivity enhancement factor (EF) of 180 was achieved for InHg. The detection limit obtained after the preconcentration of 100 mL of sample was 3.6 ng L-1 of InHg. The relative standard deviation (RSD) was 4.1% (at 1 µg L-1 InHg and n = 10) calculated from the peak height of the absorbance signals (Gaussian form and reproducible peaks). This work reports the first application of the IL-3D graphene-Ni foam in an on-line µSPE preconcentration system for the speciation analysis of Hg in mineral, tap, and river water samples.

12.
J Trace Elem Med Biol ; 58: 126441, 2020 Mar.
Article in English | MEDLINE | ID: mdl-31812871

ABSTRACT

The interest in inorganic Hg toxicity and carcinogenicity has been pointed to target organs such as kidney, brain or placenta, but only a few studies have focused on the mammary gland. In this work, analytical combination techniques (SDS-PAGE followed by CV-AFS, and nanoUPLC-ESI-MS/MS) were used to determine proteins that could bind Hg in three human mammary cell lines. Two of them were tumorigenic (MCF-7 and MDA-MB-231) and the other one was the non-tumorigenic cell line (MCF-10A). There are no studies that provide this kind of information in breast cell lines with IHg treatment. Previously, we described the viability, uptake and the subcellular distribution of Hg in human breast cells and analysis of RNA-seq about the genes that encode proteins which are related to cytotoxicity of Hg. This work provides important protein candidates for further studies of Hg toxicity in the mammary gland, thus expanding our understanding of how environmental contaminants might affect tumor progression and contribute with future therapeutic methods.


Subject(s)
Mammary Glands, Human/cytology , Mercury/toxicity , Metals/metabolism , Proteomics , Cell Line , Chromatography, High Pressure Liquid , Humans , Protein Binding/drug effects , Proteins/metabolism
13.
Environ Sci Pollut Res Int ; 27(3): 2580-2587, 2020 Jan.
Article in English | MEDLINE | ID: mdl-31832941

ABSTRACT

The vulnerability of aquatic ecosystems due to the entry of cadmium (Cd) is a concern of public and environmental health. This work explores the ability of tissues and symbiotic corpuscles of Pomacea canaliculata to concentrate and depurate Cd. From hatching to adulthood (4 months), snails were cultured in reconstituted water, which was a saline solution in ASTM Type I water. Then, adult snails were exposed for 8 weeks (exposure phase) to Cd (5 µg/L) and then returned to reconstituted water for other 8 weeks (depuration phase). Cadmium concentration in the digestive gland, kidney, head/foot and viscera (remaining of the snail body), symbiotic corpuscles, and particulate excreta was determined by electrothermal atomic absorption spectrometry. After exposure, the digestive gland showed the highest concentration of Cd (BCF = 5335). Symbiotic corpuscles bioaccumulated Cd at a concentration higher than that present in the water (BCF = 231 for C symbiotic corpuscles, BCF = 8 for K symbiotic corpuscles). No tissues or symbiotic corpuscles showed a significant change in the Cd levels at different time points of the depuration phase (weeks 8, 9, 10, 12, and 16). The symbiotic depuration through particulate excreta was faster between weeks 8 and 10, and then slower after on. Our findings show that epithelial cells of the digestive gland of P. canaliculata and their symbiotic C corpuscles are sensitive places for the bioindication of Cd in freshwater bodies.


Subject(s)
Cadmium , Water Pollutants, Chemical , Animals , Cadmium/chemistry , Ecosystem , Environmental Biomarkers , Fresh Water/analysis , Fresh Water/chemistry , Snails , Symbiosis
14.
Talanta ; 198: 146-153, 2019 Jun 01.
Article in English | MEDLINE | ID: mdl-30876542

ABSTRACT

A dispersive liquid-liquid microextraction (DLLME) method was developed based on the application of a magnetic ionic liquid (MIL) used as extractant phase for trace As determination in honey samples by electrothermal atomic absorption spectrometry (ETAAS). The procedure was simple, efficient and did not require a centrifugation stage. The As(III) species was preconcentrated by chelation with ammonium diethyldithiophosphate under acidic conditions at 3 mol L-1 HCl, followed by the extraction of the chelated analyte with the MIL trihexyl(tetradecyl)phosphonium tetrachloroferrate (III) ([P6,6,6,14]FeCl4) and acetonitrile as dispersant. The MIL phase containing the analyte was separated simply by a magnet. The collected aliquot of the MIL phase was injected directly into the graphite furnace of ETAAS for As determination. Under optimal experimental conditions, an extraction efficiency of 99% and a sensitivity enhancement factor of 110 were obtained. The limit of detection was 12 ng L-1 As and the relative standard deviation 3.9% (at 1 µg L-1 As and n = 10), calculated from the peak height of the absorbance signals. The linear range obtained was 0.02-5.0 µg L-1. This work reports the first application of the MIL [P6,6,6,14]FeCl4 along with the DLLME technique for the determination of As in honeys.


Subject(s)
Arsenic/analysis , Honey/analysis , Ionic Liquids/chemistry , Liquid Phase Microextraction , Ionic Liquids/chemical synthesis , Magnetic Fields , Spectrophotometry, Atomic , Temperature
15.
Anal Bioanal Chem ; 410(19): 4715-4723, 2018 Jul.
Article in English | MEDLINE | ID: mdl-29675708

ABSTRACT

A simple, highly efficient, batch, and centrifuge-less dispersive liquid-liquid microextraction method based on a magnetic ionic liquid (MIL-DLLME) and electrothermal atomic absorption spectrometry (ETAAS) detection was developed for ultra-trace Cd determination in honey. Initially, Cd(II) was chelated with ammonium diethyldithiophosphate (DDTP) at pH 0.5 followed by its extraction with the MIL trihexyl(tetradecyl)phosphonium tetrachloroferrate(III) ([P6,6,6,14]FeCl4) and acetonitrile as dispersant. The MIL phase containing the analyte was separated from the aqueous phase using only a magnet. A back-extraction procedure was applied to recover Cd from the MIL phase using diluted HNO3 and this solution was directly injected into the graphite furnace of ETAAS instrument. An extraction efficiency of 93% and a sensitivity enhancement factor of 112 were obtained under optimal experimental conditions. The detection limit (LOD) was 0.4 ng L-1 Cd, while the relative standard deviation (RSD) was 3.8% (at 2 µg L-1 Cd and n = 10), calculated from the peak height of absorbance signals. This work reports the first application of the MIL [P6,6,6,14]FeCl4 along with the DLLME technique for the successful determination of Cd at trace levels in different honey samples. Graphical abstract Preconcentration of ultratraces of Cd in honey using a magnetic ionic liquid and dispersive liquid-liquid microextraction technique.


Subject(s)
Cadmium/analysis , Honey/analysis , Ionic Liquids/chemistry , Liquid Phase Microextraction/methods , Magnets/chemistry , Spectrophotometry, Atomic/methods , Cadmium/isolation & purification , Equipment Design , Limit of Detection , Liquid Phase Microextraction/instrumentation , Magnetics/instrumentation , Magnetics/methods , Osmolar Concentration , Spectrophotometry, Atomic/instrumentation
16.
Biometals ; 31(1): 69-80, 2018 02.
Article in English | MEDLINE | ID: mdl-29178026

ABSTRACT

The viability, cellular uptake and subcellular distribution of heavy metal Hg, were determined in human mammary cell lines (MCF-7, MDA-MB-231 and MCF-10A). It was observed that Hg had the capacity of being excluded from the cells with a different type of possible transporters. MCF-7 cells showed the lowest viability, while the other two cell lines were much more resistant to Hg treatments. The intracellular concentration of Hg was higher at lower exposure times in MCF-10A cells and MCF-7 cells; but as the time was increased only MDA-MB-231 showed the capacity to continue introducing the metal. In MCF-7 and MCF-10A cells the subcellular distribution of Hg was higher in cytosolic fraction than nucleus and membrane, but MDA-MB-231 showed membrane and nucleus fraction as the enriched one. The analysis of RNA-seq about the genes or family of genes that encode proteins which are related to cytotoxicity of Hg evidenced that MCF-10A cells and MCF-7 cells could have an active transport to efflux the metal. On the contrary, in MDA-MB-231 no genes that could encode active transporters have been found.


Subject(s)
Cell Membrane/drug effects , Epithelial Cells/drug effects , Mercury/metabolism , Organic Cation Transport Proteins/genetics , Cations, Divalent , Cell Line , Cell Membrane/metabolism , Cell Nucleus/drug effects , Cell Nucleus/metabolism , Cell Survival/drug effects , Epithelial Cells/metabolism , Epithelial Cells/pathology , Female , Gene Expression Profiling , Gene Expression Regulation , Humans , Ion Transport , Kinetics , MCF-7 Cells , Mammary Glands, Human/drug effects , Mammary Glands, Human/metabolism , Mammary Glands, Human/pathology , Mercury/toxicity , Organ Specificity , Organic Cation Transport Proteins/classification , Organic Cation Transport Proteins/metabolism , Signal Transduction
17.
Food Chem ; 242: 272-278, 2018 Mar 01.
Article in English | MEDLINE | ID: mdl-29037689

ABSTRACT

The feasibility of the application of chemometric techniques associated with multi-element analysis for the classification of grape seeds according to their provenance vineyard soil was investigated. Grape seed samples from different localities of Mendoza province (Argentina) were evaluated. Inductively coupled plasma mass spectrometry (ICP-MS) was used for the determination of twenty-nine elements (Ag, As, Ce, Co, Cs, Cu, Eu, Fe, Ga, Gd, La, Lu, Mn, Mo, Nb, Nd, Ni, Pr, Rb, Sm, Te, Ti, Tl, Tm, U, V, Y, Zn and Zr). Once the analytical data were collected, supervised pattern recognition techniques such as linear discriminant analysis (LDA), partial least square discriminant analysis (PLS-DA), k-nearest neighbors (k-NN), support vector machine (SVM) and Random Forest (RF) were applied to construct classification/discrimination rules. The results indicated that nonlinear methods, RF and SVM, perform best with up to 98% and 93% accuracy rate, respectively, and therefore are excellent tools for classification of grapes.


Subject(s)
Mass Spectrometry/methods , Metals/analysis , Seeds/chemistry , Vitis/chemistry , Vitis/classification , Argentina , Discriminant Analysis , Least-Squares Analysis , Soil
18.
J Chromatogr A ; 1491: 117-125, 2017 Mar 31.
Article in English | MEDLINE | ID: mdl-28249719

ABSTRACT

Different ionic liquids (ILs) were assayed as mobile phase modifiers for the separation and determination of selenite [Se(IV)], selenate [Se(VI)], selenomethionine (SeMet) and Se-methylselenocysteine (SeMeSeCys) by reversed-phase high-performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry (RP-HPLC-HG-AFS). The use of several ILs: 1-butyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride ([C6mim]Cl), 1-octyl-3-methylimidazolium chloride, 1-dodecyl-3-methylimidazolium bromide, 1-hexadecyl-3-methylimidazolium bromide and tributyl(methyl)phosphonium methylsulphate was evaluated. Also, the effect of pH, buffer type and IL concentration on the separation of Se species was studied. Complete separation was attained within 12min using a C8 column and a gradient performed with a mobile phase containing 0.1% (v/v) [C6mim]Cl at pH 6.0. The proposed method allows the separation of inorganic and organic Se species in a single chromatographic run, adding further benefits over already reported methods based on RP-HPLC. In addition, the influence of ILs on the AFS signals of each Se species was evaluated and a multivariate methodology was used for optimization of AFS sensitivity. The limits of detection were 0.92, 0.86, 1.41 and 1.19µgL-1 for Se(IV), Se(VI), SeMet and SeMeSeCys, respectively. The method was successfully applied for speciation analysis of Se in complex samples, such as wine, beer, yeast and garlic.


Subject(s)
Beverages/analysis , Chromatography, Reverse-Phase/methods , Food Analysis/methods , Organoselenium Compounds , Selenium , Spectrometry, Fluorescence/methods , Ionic Liquids/chemistry , Organoselenium Compounds/analysis , Organoselenium Compounds/chemistry , Organoselenium Compounds/isolation & purification , Selenium/analysis , Selenium/chemistry , Selenium/isolation & purification
19.
Food Chem ; 219: 102-108, 2017 Mar 15.
Article in English | MEDLINE | ID: mdl-27765204

ABSTRACT

A highly sensitive vortex assisted liquid-liquid microextraction (VA-LLME) method was developed for inorganic Se [Se(IV) and Se(VI)] speciation analysis in Allium and Brassica vegetables. Trihexyl(tetradecyl)phosphonium decanoate phosphonium ionic liquid (IL) was applied for the extraction of Se(IV)-ammonium pyrrolidine dithiocarbamate (APDC) complex followed by Se determination with electrothermal atomic absorption spectrometry. A complete optimization of the graphite furnace temperature program was developed for accurate determination of Se in the IL-enriched extracts and multivariate statistical optimization was performed to define the conditions for the highest extraction efficiency. Significant factors of IL-VA-LLME method were sample volume, extraction pH, extraction time and APDC concentration. High extraction efficiency (90%), a 100-fold preconcentration factor and a detection limit of 5.0ng/L were achieved. The high sensitivity obtained with preconcentration and the non-chromatographic separation of inorganic Se species in complex matrix samples such as garlic, onion, leek, broccoli and cauliflower, are the main advantages of IL-VA-LLME.


Subject(s)
Brassica/chemistry , Garlic/chemistry , Liquid Phase Microextraction/methods , Selenium Compounds/analysis , Selenium/analysis , Ionic Liquids/chemistry , Limit of Detection , Pyrrolidines/analysis , Spectrophotometry, Atomic/methods , Thiocarbamates/analysis
20.
J Chromatogr A ; 1462: 44-54, 2016 Sep 02.
Article in English | MEDLINE | ID: mdl-27495368

ABSTRACT

The application of different ionic liquids (ILs) as modifiers for chromatographic separation and determination of arsenite [As(III)], arsenate [As(V)], dimethylarsonic acid (DMA) and monomethylarsonic acid (MMA) species in wine samples, by reversed-phase high performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry detection (RP-HPLC-HG-AFS) was studied in this work. Several factors influencing the chromatographic separation of the As species, such as pH of the mobile phase, buffer solution concentration, buffer type, IL concentration and length of alkyl groups in ILs were evaluated. The complete separation of As species was achieved using a C18 column in isocratic mode with a mobile phase composed of 0.5% (v/v) 1-octyl-3-methylimidazolium chloride ([C8mim]Cl) and 5% (v/v) methanol at pH 8.5. A multivariate methodology was used to optimize the variables involved in AFS detection of As species after they were separated by HPLC. The ILs showed remarkable performance for the separation of As species, which was obtained within 18min with a resolution higher than 0.83. The limits of detection for As(III), As(V), MMA and DMA were 0.81, 0.89, 0.62 and 1.00µg As L(-1). The proposed method was applied for As speciation analysis in white and red wine samples originated from different grape varieties.


Subject(s)
Arsenic/analysis , Arsenic/isolation & purification , Ionic Liquids/chemistry , Spectrometry, Fluorescence/methods , Spectrophotometry, Atomic/methods , Wine/analysis , Arsenic/chemistry , Arsenicals/analysis , Arsenicals/isolation & purification , Arsenites/analysis , Arsenites/isolation & purification , Buffers , Chromatography, High Pressure Liquid , Hydrogen-Ion Concentration , Limit of Detection , Vitis/chemistry , Vitis/classification
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