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1.
Chemosphere ; 338: 139480, 2023 Oct.
Article in English | MEDLINE | ID: mdl-37453517

ABSTRACT

In this work, an evaluation of the occurrence of fifteen phthalates, four metabolites and one adipate in different groundwater, seawater and wastewater samples has been carried out due to their relevance on human health as they act as endocrine disruptors. For this purpose, a sustainable, fast and easy-handling vortex-assisted liquid-liquid microextraction method using a natural hydrophobic deep eutectic solvent based on menthol and carvacrol as extraction agent, combined with ultra-high performance liquid chromatography-mass spectrometry technique, has been developed and applied for the first time. An optimization was performed to evaluate four important factors affecting the extraction performance, and an analytical validation was carried out in terms of matrix effect, linearity, extraction efficiency, and sensitivity. Recovery values were obtained in the range 72-119% for all analytes (except for monoethyl phthalate: 61.1-72.3%) with relative standard deviation values lower than 17%. Limits of quantification were found between 0.91 and 8.09 µg L-1. As a result of the assessment of 31 different environmental water samples, monoethyl phthalate, diethyl phthalate, dibutyl phthalate and bis (2-ethylhexyl) phthalate were detected and quantified at different concentrations in the range 2.59-21.17 µg L-1 in 6 samples, and diallyl phthalate, butyl benzyl phthalate, dipentyl phthalate, dicyclohexyl phthalate, dihexyl phthalate and bis (2-ethylhexyl) adipate were detected in 20 more, showing the exposition of the population to these hazardous substances.


Subject(s)
Endocrine Disruptors , Environmental Pollutants , Phthalic Acids , Humans , Solvents/chemistry , Deep Eutectic Solvents , Endocrine Disruptors/analysis , Gas Chromatography-Mass Spectrometry/methods , Environmental Pollutants/analysis , Phthalic Acids/analysis , Water/chemistry , Adipates/analysis
2.
Food Res Int ; 164: 112424, 2023 02.
Article in English | MEDLINE | ID: mdl-36737999

ABSTRACT

In this work, a natural deep eutectic solvent was used for the liquid-liquid microextraction of fourteen phthalates and one adipate from bottled waters. The methodology was validated in terms of matrix effect, linearity, recovery, and limits of quantification (LOQs). Optimum extraction conditions (10 mL of water at pH 8.0 with 100 µL of thymol: menthol 2:1 (n/n) as solvent) provided satisfactory determination coefficients (≥ 0.9977), recovery values (82-127%), and LOQs (0.018-0.523 µg/L). The effects of temperature and storage time on plasticizer presence were studied for 36 different brands stored at 4 °C, room temperature, and 45 °C, and analyzed at 0, 24, 48, 72 h, and 1 week. Only diethyl-, dibutyl-, bis-(2-ethylhexyl) phthalates, and bis-(2-ethylhexyl) adipate were detected. The results showed that there is no relationship between the storage conditions, the bottle material or water carbonation, and the occurrence of these plasticizers, suggesting that residues are introduced during production or by the water supply. The estimated daily intake was lower than the total daily intake set by the European Food Safety Authority.


Subject(s)
Drinking Water , Liquid Phase Microextraction , Plasticizers , Temperature , Solvents , Adipates/analysis
3.
Food Chem ; 400: 134089, 2023 Jan 30.
Article in English | MEDLINE | ID: mdl-36075167

ABSTRACT

In this work, the development of an analytical method for the evaluation of a wide variety of pesticide residues in cereals and pseudo-cereals widely consumed has been carried out. A QuEChERS method was used as extraction and clean-up procedure prior to separation and quantification of the target analytes by ultra-high performance liquid chromatography coupled to mass spectrometry using a single quadrupole-time-of-flight analyser. The methodology was validated for oat, rye, spelt, barley and quinoa matrices, following the European Commission guidelines (SANTE/11312/2021), achieving good absolute recovery values in the range 60-124% with relative standard deviation values lower than 20% and providing limits of quantification of the method in the low mg/kg range, in accordance with the maximum residue limits established by European policies. Finally, considering the importance of cereals in general population diet, the analysis of 60 samples was carried out in order to assure their safe consumption.


Subject(s)
Pesticide Residues , Chromatography, High Pressure Liquid/methods , Edible Grain/chemistry , Food Contamination/analysis , Humans , Pesticide Residues/analysis , Spain
4.
Polymers (Basel) ; 14(17)2022 Aug 29.
Article in English | MEDLINE | ID: mdl-36080636

ABSTRACT

Corneal opacities are a leading cause of visual impairment that affect 4.2 million people annually. The current treatment is corneal transplantation, which is limited by tissue donor shortages. Corneal engineering aims to develop membranes that function as scaffolds in corneal cell transplantation. Here, we describe a method for producing transplantable corneal constructs based on a collagen vitrigel (CVM) membrane and corneal endothelial cells (CECs). The CVMs were produced using increasing volumes of collagen type I: 1X (2.8 µL/mm2), 2X, and 3X. The vitrification process was performed at 40% relative humidity (RH) and 40 °C using a matryoshka-like system consisting of a shaking-oven harboring a desiccator with a saturated K2CO3 solution. The CVMs were characterized via SEM microscopy, cell adherence, FTIR, and manipulation in an ex vivo model. A pilot transplantation of the CECs/CVM construct in rabbits was also carried out. The thickness of the CVMs was 3.65-7.2 µm. The transparency was superior to a human cornea (92.6% = 1X; 94% = 2X; 89.21% = 3X). SEM microscopy showed a homogenous surface and laminar organization. The cell concentration seeded over the CVM increased threefold with no significant difference between 1X, 2X, and 3X (p = 0.323). The 2X-CVM was suitable for surgical manipulation in the ex vivo model. Constructs using the CECs/2X-CVM promoted corneal transparency restoration.

5.
Laryngoscope Investig Otolaryngol ; 7(2): 417-424, 2022 Apr.
Article in English | MEDLINE | ID: mdl-35434333

ABSTRACT

Background: The standard treatment for endemic goiter is usually total thyroidectomy. In low- and middle-income countries, the management of thyroid disease, which is commonplace in fully developed countries, is not always possible. The purpose of this study is to establish a treatment algorithm to calculate the extent of thyroidectomy based on the risk factors of each patient. Methods: This is a retrospective observational study conducted during the period between 2017 and 2019. A total of 287 patients with thyroid pathology were treated in Maragua Hospital (Kenya). The results of surgical treatment were analyzed after the implementation of an individualized treatment protocol. Results: One hundred and sixty patients with different types of goiter underwent surgery: solitary nodule (54.4%), multi-nodular goiter (30.6%), diffuse goiter (10.6%), and intrathoracic goiter (3.8%). The techniques used were hemithyroidectomy (78.8%), Dunhill thyroidectomy (9.4%), bilateral subtotal thyroidectomy (6.9%), and total thyroidectomy (3.1%). There was no mortality. The surgical morbidity rate was 16% (only one major complication (3b)). Two cases of dysphonia were resolved in the first week. There were three cases of symptomatic hypocalcaemia, two of which resolved in the first week and the other of which was definitive. The follow-up at 6 months was 67%. The cancer rate found in the resection specimens was 5%. Discussion: The implementation of individualized surgical protocols for thyroid surgery in sub-Saharan Africa can improve outcomes. The cooperation projects can increase access to complex surgical treatment for patients with limited resources in low- and middle-income countries.

6.
J Chromatogr A ; 1670: 462988, 2022 May 10.
Article in English | MEDLINE | ID: mdl-35378354

ABSTRACT

Magnetic nanoparticles of Fe3O4 coated with polyaniline have been synthesised through chemical co-precipitation, and successfully characterised using different techniques such as FT-IR and X-ray diffraction. Such nanocomposite was applied as sorbent for a new magnetic micro-dispersive solid phase extraction procedure for the extraction of seven plastic migrants in jelly samples, followed by determination using ultra-high performance liquid chromatography-tandem mass spectrometry. Optimisation of several parameters that could affect extraction efficiency has been performed both by a conventional one-step-at-a-time approach and the use of a Box Behnken experimental design. The developed method was successfully validated obtaining recovery values in the range 70-124% with relative standard deviations lower than 20%, limits of quantification in the range 0.0106-0.0171 µg/L, and R2 values higher than 0.9915 for all the analytes. The greenness of the procedure was also evaluated using the AGREE calculator. Finally, the developed method was applied for the determination of plastic migrants in a group of 11 commercial jellies acquired in local stores. Results showed the presence of BBP in almost all the samples and DCHP in three of them, as well as DEHA, which was detected in another three commercial samples and quantified at a concentration of 2.17 µg/L in another one.


Subject(s)
Liquid Phase Microextraction , Plastics , Aniline Compounds , Chromatography, High Pressure Liquid/methods , Magnetic Phenomena , Plastics/analysis , Solid Phase Extraction , Spectroscopy, Fourier Transform Infrared , Tandem Mass Spectrometry/methods
7.
J Chromatogr A ; 1669: 462922, 2022 Apr 26.
Article in English | MEDLINE | ID: mdl-35287030

ABSTRACT

In this work, the application of betaine-based hydrophilic natural deep eutectic solvents (NADESs) as green extraction solvents was proposed for the first time for the evaluation of twelve pesticides in citrus and olive by-products intended to be applied as potential sources of compounds with neuroprotective activity against Alzheimer Disease. Ultrasound-assisted extraction of selected pesticides was followed by separation and determination using gas chromatography coupled to single quadrupole mass spectrometry. Eight NADESs were tested using different hydrogen bond donors (i.e. citric and lactic acid, fructose, glucose, glycerol, propylene glycol, propionic and butanoic acid). Other factors affecting extraction efficiency were also evaluated using a step-by-step approach. Eight mL of a mixture composed of 60% betaine:propylene glycol NADES at a molar ratio 1:4 and 40% of water, as well as 30 min of ultrasound-assisted extraction were selected as the most adequate conditions. The methodology was validated prior to its application in citrus and olive by-products. Recovery values were between 73 and 115% (RSD% < 20%), while limits of quantification of the method were in the range 8.5-128.8 µg/kg, which demonstrates the suitability of the procedure to determine the selected group of pesticides, usually applied in citrus and olive crops, at the legislated levels. The greenness of the procedure was also evaluated using AGREE calculator. Finally, the whole method was applied for the safety assessment of seven olive leaf samples and seven citrus by-products produced in Spain, finding the presence of several of the evaluated compounds at concentrations higher than the established limits for similar products.


Subject(s)
Citrus , Olea , Deep Eutectic Solvents , Gas Chromatography-Mass Spectrometry , Solvents/chemistry
8.
Food Chem ; 377: 131921, 2022 May 30.
Article in English | MEDLINE | ID: mdl-34974406

ABSTRACT

In this work, the analysis of alkylphenols, bisphenols and alkylphenol ethoxylates in bottled waters, kombuchas and water kefir was performed through a vortex-assisted dispersive liquid-liquid microextraction method based on a natural hydrophobic eutectic solvent. For this purpose, mixtures of monoterpenes and fatty acids were employed. Different factors affecting extraction were optimized and the method was validated in terms of matrix effect, linearity, limits of detection and recovery. Recovery values varied between 70.0 and 124.3% (except for 4-tert-butylphenol: 67.0% and 4-n-nonylphenol: 60.8% in water kefir) and limits of detection were in the range 0.10 ng/L - 2.99 µg/L. Finally, 8 bottled waters, 8 kombuchas and 4 water kefirs were analyzed and 4-tert-octylphenol monoethoxylate was detected in water (20.28 ± 0.99 - 62.08 ± 3.63 µg/L). This is the first application analyzing xenobiotic contaminants in kombucha and water kefir and the first time in which the three types of compounds are simultaneously extracted by dispersive liquid-liquid microextraction.


Subject(s)
Drinking Water , Liquid Phase Microextraction , Water Pollutants, Chemical , Deep Eutectic Solvents , Limit of Detection , Solvents , Water Pollutants, Chemical/analysis
9.
Anal Bioanal Chem ; 413(7): 1967-1981, 2021 Mar.
Article in English | MEDLINE | ID: mdl-33534021

ABSTRACT

A non-ionic hydrophobic natural deep eutectic solvent (HNADES) based on thymol and menthol was proposed for the liquid-liquid microextraction of fourteen phthalates and one adipate from environmental water samples. Separation, identification, and quantification were achieved by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry. The main factors affecting the extraction efficiency were thoroughly studied. Sample pH of 8 and 100 µL of thymol:menthol at molar ratio 2:1 were selected as the best conditions, while ionic strength and type of dispersant solvent were not relevant for the extraction of the target compounds. The whole methodology was validated for treated wastewater, runoff, and pond water matrices, using di-n-butyl phthalate-3,4,5,6-d4 and dihexyl phthalate-3,4,5,6-d4 as surrogates. Recovery ranged from 70 to 127% with relative standard deviation values lower than 14%. Limits of quantification of the method were in the range 0.042-0.425 µg/L for treated wastewater, 0.015-0.386 µg/L for runoff, and 0.013-0.376 µg/L for pond water. The methodology was applied for the analysis of real treated wastewater, runoff, and pond water samples from different places of Tenerife and Gran Canaria (Canary Islands) finding the presence of diethyl phthalate, diallyl phthalate, dipropyl phthalate, benzylbutyl phthalate, di-n-butyl phthalate, bis-(2-n-butoxyethyl) phthalate, di-n-pentyl phthalate, dicyclohexyl phthalate, and bis-(2-ethylhexyl) phthalate at concentrations between 105.2 and 3414 ng/L.

10.
J Chromatogr A ; 1637: 461858, 2021 Jan 25.
Article in English | MEDLINE | ID: mdl-33422793

ABSTRACT

Synthesised polypyrrole-coated Fe3O4 magnetic nanoparticles have been successfully characterised and applied as sorbent for the magnetic-micro-dispersive solid-phase extraction of eleven phthalic acid esters from jelly and apple-based beverage matrices widely consumed by the population and, especially, by children. Sorbent was synthesised through chemical coprecipitation and subsequently characterised by different techniques. The influence of several parameters on the extraction efficiency was exhaustively evaluated using a step-by-step strategy. The separation and quantification of the selected phthalates were performed by ultra-high performance liquid chromatography coupled to tandem mass spectrometry. The validation of the methodology was carried out for jellies and apple-based beverages, employing dihexyl phthalate-3,4,5,6-d4 as the surrogate standard. Relative recovery values were in the range 70-114% for both matrices and relative standard deviations below 20% were obtained. The limits of quantification of the method were found in the range 0.147-0.416 µg/L. Feasibility of the developed methodology was proved by the analysis of commercialised jelly and apple-based beverage products.


Subject(s)
Beverages/analysis , Magnetics , Malus/chemistry , Phthalic Acids/analysis , Polymers/chemistry , Pyrroles/chemistry , Solid Phase Microextraction/methods , Tandem Mass Spectrometry/methods , Adsorption , Calibration , Chromatography, High Pressure Liquid , Humans , Hydrogen-Ion Concentration , Nanoparticles/chemistry , Reproducibility of Results , Solvents/chemistry
11.
Molecules ; 27(1)2021 Dec 28.
Article in English | MEDLINE | ID: mdl-35011411

ABSTRACT

A vortex-assisted liquid-liquid microextraction, based on a natural hydrophobic deep eutectic solvent made from the monoterpene thymol and octanoic fatty acid, was employed for the analysis of 11 phthalate esters and one adipate in kombucha (a tea-based fermented beverage). Separation and determination were performed using an ultra-high performance liquid chromatography (UHPLC) system coupled to a single quadrupole mass spectrometer. Confirmatory analyses were carried out through UHPLC tandem mass spectrometry. The full method was validated in terms of matrix effect, matrix-matched calibration, sensitivity, recovery, limits of detection and quantification and repeatability. Satisfactory determination coefficients for quadratic calibration curves (≥0.9938), recovery values (67-120%) and limits of detection (0.07-5.45 µg/L) were obtained. Analysis of 26 kombucha samples reported concentrations for dibutyl phthalate and dimethyl phthalate in the range between the limit of quantification (LOQ) and 16.18 ± 1.14 µg/L, although these phthalates were also detected under the LOQ in some of the analyzed samples. Only one of the samples bottled in plastic containers (7) did not present residues while only five of the 19 samples in glass bottles contained any plasticizer. However, the highest concentration was found in a kombucha bottled in food-grade glass. This work represents the first application in which phthalates and adipates are analyzed in kombuchas.


Subject(s)
Deep Eutectic Solvents/chemistry , Fermented Beverages/analysis , Hydrophobic and Hydrophilic Interactions , Liquid Phase Microextraction , Plastics/analysis , Chromatography, High Pressure Liquid , Limit of Detection , Liquid Phase Microextraction/methods , Reproducibility of Results , Tandem Mass Spectrometry
12.
Foods ; 9(11)2020 Oct 27.
Article in English | MEDLINE | ID: mdl-33121047

ABSTRACT

In this work, the QuEChERS method coupled to liquid chromatography-time-of flight-mass spectrometry and gas chromatography-triple quadrupole-mass spectrometry were applied for the evaluation of pesticide residues and risk assessment in red wines. The methodologies were successfully validated for 173 pesticides. Recovery values were in the range 75-100% for almost all pesticides and limits of quantification were between 2.60 and 21.39 µg/kg, which are in good agreement with the maximum residue limits (MRLs) established by the European Commission for pesticides in wine grapes. Finally, the analysis of 84 red wine samples from the Canary Islands, the Iberian Peninsula, and Cape Verde was carried out, which found the presence of 31 pesticide residues. However, the risk assessment disclosed that despite the large number of pesticides and the concentrations found, which in some cases exceeded the MRLs, the consumption of these wines, without considering a possible cumulative effect, does not entail a risk to the consumers.

13.
J Chromatogr A ; 1632: 461596, 2020 Nov 22.
Article in English | MEDLINE | ID: mdl-33045497

ABSTRACT

Despite nearly 80 years of advancements in gas chromatography (GC), indirect chemical matrix effects (MEs), known as the matrix-induced response enhancement effect, still occur to cause a high bias in the GC analysis of susceptible analytes, unless precautions are taken. Matrix-matched calibration is one common option used in GC to compensate for the MEs, but this approach is usually inconvenient, imprecise, and inefficient. Other options, such as the method of standard additions, surface deactivation techniques, chemical derivatizations, priming the GC, and/or use of internal standards, also have flaws in practice. When methods are accommodating, the use of analyte protectants (APs) can provide the best practical solution to not only overcome MEs, but also to maximize analyte signal by increasing chromatographic and detection efficiencies for the analytes. APs address the source of MEs in every injection by filling active sites in the GC inlet, column, and detector, particularly in GC-MS, rather than the analytes that would otherwise undergo degradation, peak tailing, and/or diminished response due to interactions with the active sites. The addition of an adequate amount of APs (e.g. sugar derivatives) to all calibration standards and final extracts alike often leads to lower detection limits, better accuracy, narrower peaks, and greater robustness than the other options to compensate for MEs in GC. This article consists of a critical review of the scientific literature, proposal of mechanisms and theory, and re-evaluation studies involving APs for the first time in GC-orbitrap and GC-MS/MS with a high-efficiency ion source design. The findings showed that 1 µg each of co-injected shikimic acid and sorbitol in the former case, and 1 µg shikimic acid alone in the latter case, led to high quality results in multi-residue analysis of pesticides and environmental contaminants.


Subject(s)
Chromatography, Gas/methods , Calibration , Gas Chromatography-Mass Spectrometry , Publications , Signal Processing, Computer-Assisted
14.
Electrophoresis ; 41(20): 1768-1775, 2020 10.
Article in English | MEDLINE | ID: mdl-32297997

ABSTRACT

The separation of 11 phthalic acid ester (PAEs) was carried out by nano-liquid chromatography coupled to ultraviolet and MS detection. Preliminary experiments were achieved in order to select suitable stationary phases and chromatographic conditions. The baseline separation was obtained, for all compounds, with an XBridgeTM C18 column in less than 15 min, working in step gradient mode. The sensitivity of the method was improved by on-column focusing. PAEs were extracted from alcoholic and nonalcoholic beverages using vortex-assisted emulsification dispersive liquid-liquid microextration and natural deep eutectic solvents. The whole method was validated in terms of linearity, sensitivity, precision, recovery, and repeatability. Combination of both off-line sample preparation preconcentration and large injection volume led to obtain LOQs in the range 5-47 ng/mL. The developed nano-LC-UV method was extended to MS detection to confirm the presence of PAEs in some beverages commercialized in different types of packaging.


Subject(s)
Chromatography, High Pressure Liquid/methods , Liquid Phase Microextraction/methods , Nanotechnology/methods , Phthalic Acids/analysis , Food Packaging , Limit of Detection , Linear Models , Reproducibility of Results , Solvents/chemistry , Wine/analysis
15.
Anal Bioanal Chem ; 412(7): 1551-1561, 2020 Mar.
Article in English | MEDLINE | ID: mdl-31953715

ABSTRACT

In this work, the development of a simple, fast and reliable method for the evaluation of a group of twelve plastic migrants in alcoholic and non-alcoholic beverages widely consumed by the population has been carried out. For that, a modified QuEChERS method for the extraction and preconcentration of the target compounds has been used prior to their separation and quantification by gas chromatography coupled to triple quadrupole tandem mass spectrometry. The whole methodology was validated for beer, cider and grape juice matrices, using dibutyl phthalate-3,4,5,6-d4 as surrogate. Recovery ranged from 75 to 120% for all matrices with relative standard deviation values lower than 20%, and the limits of quantification of the method were achieved in the range 0.034-1.415 µg/L. Finally, the analysis of different beer, cider and grape juice samples commercialised in different supermarkets of Tenerife was carried out, finding the presence of four of the evaluated phthalates in the range 0.14-1.1 µg/L in some of the evaluated beers, six of them in several cider samples, in the range 0.3-2.1 µg/L, and one in the range 1.2-1.5 µg/L in three of the analysed grape juices.


Subject(s)
Alcoholic Beverages/analysis , Beverages/analysis , Gas Chromatography-Mass Spectrometry/methods , Plastics/analysis , Tandem Mass Spectrometry/methods , Limit of Detection , Reproducibility of Results
16.
Food Chem ; 312: 125798, 2020 May 15.
Article in English | MEDLINE | ID: mdl-31887621

ABSTRACT

In this work, a green, inexpensive, simple and fast deep eutectic solvent (DES)-based dispersive liquid-liquid microextraction was evaluated, for the first time, for the extraction of phthalates (i.e. benzylbutyl phthalate, diisobutyl phthalate, diisopentyl phthalate, di-n-pentyl phthalate, di-(2-ethylhexyl) phthalate, di-n-octyl phthalate, diisononyl phthalate, diisodecyl phthalate) from different beverages. Separation and determination were achieved by high performance liquid chromatography-diode-array detection while confirmation was carried out by tandem mass spectrometry. The main factors affecting the extraction such as type and volume of DES and emulsifier, pH and ionic strength, were optimised. Choline chloride:phenol-based DES showed the best results. The methodology was validated for tea, apple-based beverage and pineapple juice. Recovery values ranged from 84 to 120% with relative standard deviation values lower than 11%. Limits of detection of the method were in the range 5.1-14.2 µg L-1 for tea, 5.3-17.8 µg L-1 for apple beverages and 5.9-15.6 µg L-1 for pineapple juices.


Subject(s)
Fruit and Vegetable Juices/analysis , Phthalic Acids/isolation & purification , Chromatography, High Pressure Liquid/methods , Color , Liquid Phase Microextraction/methods , Solvents/chemistry , Tandem Mass Spectrometry/methods
17.
Chemosphere ; 236: 124377, 2019 Dec.
Article in English | MEDLINE | ID: mdl-31548171

ABSTRACT

In this study, the application of different nanomaterials as dispersants in matrix solid phase dispersion has been evaluated for the extraction of fifteen phthalates from different environmental samples prior to their separation and quantification by ultra-high performance liquid chromatography coupled to triple quadrupole mass spectrometry. Within the evaluated nanomaterials, including graphene oxide, multi-walled carbon nanotubes and iron 1,3,5-benzenetricarboxylate metal-organic framework, the last one showed the best results in terms of extraction capacity and sample clean-up. The effects of the different parameters affecting the sample pretreatment efficiency were exhaustively evaluated. The whole methodology was validated for agricultural soil and sand, using dibutyl phthalate-3,4,5,6-d4 as surrogate. Recovery values ranged from 70 to 120% for both matrices with RSD values lower than 20% and the limits of quantification of the method achieved were in the range 0.14-2.7 µg/kg dry weight. Finally, the analysis of soil samples from different locations of Tenerife (Canary Islands, Spain) was carried out finding the presence of BBP, DIBP and DBP in the range 5-52 µg/kg dry weight in agricultural soils, and DIPP, DNOP and DINP in the range 2-101 µg/kg dry weight in sand samples.


Subject(s)
Dibutyl Phthalate/isolation & purification , Nanostructures/chemistry , Soil Pollutants/isolation & purification , Solid Phase Extraction/methods , Chromatography, High Pressure Liquid , Dibutyl Phthalate/analysis , Graphite/analysis , Nanotubes, Carbon/chemistry , Soil/chemistry , Soil Pollutants/analysis , Solid Phase Extraction/instrumentation , Spain , Tandem Mass Spectrometry
18.
Talanta ; 195: 236-244, 2019 Apr 01.
Article in English | MEDLINE | ID: mdl-30625538

ABSTRACT

In the present work, a commercial metal-organic framework (Basolite® F300) has been applied for the first time as dispersive solid-phase extraction (dSPE) sorbent of eight phthalic acid esters (PAEs) (butyl benzyl phthalate, bis-2-n-butoxyethyl phthalate, bis-isopentyl phthalate, bis-n-pentyl phthalate, dicyclohexyl phthalate, di-(2-ethylhexyl) phthalate -DEHP-, di-n-octyl phthalate and diisononyl phthalate) and an adipate (bis (2-ethylhexyl) adipate), which is utilized as a PAE substitutive. Milli-Q, pond, tap and waste water were selected as samples. Dihexyl phthalate-3,4,5,6-d4 was used as procedural internal standard. High-performance liquid chromatography mass spectrometry was used for the determination of the target compounds. Optimum dSPE conditions were the following: 50 mL of the water sample (pH 6.0), 120 mg of sorbent and 15 mL of ACN as elution solvent. For the validation of the method, matrix-matched calibration and trueness of the method were addressed, obtaining determination coefficients (R2) higher than 0.9905 and relative recovery values between 70 and 118 % (RSDs < 20 %). The limits of quantification of the method were in the range 22-69 ng/L. Matrix effects were also studied. Different real samples were analysed, finding DEHP in all of them at the low µg/L level.

19.
Entropy (Basel) ; 21(2)2019 Jan 30.
Article in English | MEDLINE | ID: mdl-33266843

ABSTRACT

A physical system out of thermal equilibrium is a resource for obtaining useful work when a heat bath at some temperature is available. Information Heat Engines are the devices which generalize the Szilard cylinders and make use of the celebrated Maxwell demons to this end. In this paper, we consider a thermo-chemical reservoir of electrons which can be exchanged for entropy and work. Qubits are used as messengers between electron reservoirs to implement long-range voltage transformers with neither electrical nor magnetic interactions between the primary and secondary circuits. When they are at different temperatures, the transformers work according to Carnot cycles. A generalization is carried out to consider an electrical network where quantum techniques can furnish additional security.

20.
Phys Rev Lett ; 121(6): 060501, 2018 Aug 10.
Article in English | MEDLINE | ID: mdl-30141685

ABSTRACT

In this Letter, we establish and explore a new connection between quantum information theory and classical statistical mechanics by studying the problem of qubit losses in 2D topological color codes. We introduce a protocol to cope with qubit losses, which is based on the identification and removal of a twin qubit from the code, and which guarantees the recovery of a valid three-colorable and trivalent reconstructed color code. Moreover, we show that determining the corresponding qubit loss error threshold is equivalent to a new generalized classical percolation problem. We numerically compute the associated qubit loss thresholds for two families of 2D color code and find that with p=0.461±0.005 these are close to satisfying the fundamental limit of 50% as imposed by the no-cloning theorem. Our findings reveal a new connection between topological color codes and percolation theory, show high robustness of color codes against qubit loss, and are directly relevant for implementations of topological quantum error correction in various physical platforms.

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