RESUMO
An aptamer-functionalized stir bar sorptive extraction (SBSE) coating is described for the first time devoted to selective isolation and preconcentration of an allergenic food protein, concavanalin A (Con A), followed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF-MS) determination. For this purpose, the polytetrafluoroethylene surface of commercial magnetic stir bars was properly modified and vinylized to immobilize a thiol-modified aptamer against Con A via straightforward "thiol-ene" click chemistry. The aptamer-functionalized stir bar was employed as SBSE sorbent to isolate Con A, and several parameters that can affect the extraction efficiency were investigated. Under the optimized conditions, Con A was extracted and desorbed during 30 and 45 min, respectively, at 25 °C and 600 rpm. The SBSE MALDI-TOF-MS method provided limits of detection of 0.5 µg mL-1 for Con A. Furthermore, the SBSE coating was highly selective to Con A compared to other lectins. The developed method was successfully applied to the determination of low levels of Con A in several food matrices (i.e., white beans as well as chickpea, lentils, and wheat flours). Recoveries ranged from 81 to 97% with relative standard deviations below 7%. The aptamer-based stir bars presented suitable physical and chemical long-term stability (1 month) and a reusability of 10 and 5 extraction cycles with standards and food extracts, respectively. The developed aptamer-affinity extraction devices open up the possibility of developing novel highly selective SBSE coatings for the extraction of proteins and peptides from complex samples.
Assuntos
Oligonucleotídeos , Concanavalina A , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por MatrizRESUMO
In this study, single-stranded DNA aptamers with binding affinity to Ole e 1, the major allergen of olive pollen, were selected using systematic evolution of ligands by exponential enrichment (SELEX) method. Binding of the aptamers was firstly established by enzyme-linked oligonucleotide assay (ELONA) and aptaprecipitation assays. Additionally, aptamer-modified monolithic capillary chromatography was used in order to evaluate the recognition of this allergenic protein against other non-target proteins. The results indicated that AptOle1#6 was the aptamer that provided the highest affinity for Ole e 1. The selected aptamer showed good selective recognition of this protein, being not able to retain other non-target proteins (HSA, cyt c, and other pollen protein such as Ole e 9). The feasibility of the affinity monolithic column was demonstrated by selective recognition of Ole e 1 in an allergy skin test. The stability and reproducibility of this monolithic column was suitable, with relative standard deviations (RSDs) in retention times and peak area values of 7.8 and 9.3%, respectively (column-to-column reproducibility). This is the first study that describes the design of an efficient DNA aptamer for this relevant allergen.
Assuntos
Aptâmeros de Nucleotídeos , Olea , Alérgenos , Pólen , Reprodutibilidade dos TestesRESUMO
A hybrid material (nano-metal organic framework@organic polymer, named as nano-MOF@polymer) was applied for the first time as sorbent for on-line solid-phase extraction capillary electrophoresis with ultraviolet detection (SPE-CE-UV). The resulting material was prepared building layer-by-layer a HKUST-1 (Hong Kong University of Science and Technology-1) nano-MOF onto the polymer surface, which allowed controlling the thickness and maximizing the active surface area. The sorbent was widely characterized at micro- and nano-scale to validate the synthesis and to establish the material properties. Then, fritless microcartridges (2 mm) were assembled by packing only a few micrograms of sorbent particles and investigated for preconcentration of fluoroquinolones (FQs) in several real samples (river water, human urine and whole cow milk). Under the optimized conditions, the sample (ca. 60 µL) was loaded in separation background electrolyte (BGE, 50 mM phosphate (pH 7)), and retained analytes were eluted using a small volume of 2% v/v formic acid in methanol (ca. 50 nL). The SPE-CE-UV method was validated in terms of linearity, limit of detection (LOD), limit of quantification (LOQ), repeatability, reproducibility and reusability. The developed method showed a LOD decreasing until 1 ng L-1 when larger volumes of sample were loaded (ca. 180 µL), which was 500,000 times lower than by CE-UV. This undescribed sensitivity enhancement would arise from the homogenous and populated MOF nano-domains and the appropriate permeability of the hybrid material, which would promote high extraction efficiency and loading capacity. Furthermore, the sorbent showed appropriate selectivity regardless the analyzed complex environmental, biological or food matrix samples, achieving excellent detectability and recoveries (>90%).
Assuntos
Fluoroquinolonas , Polímeros , Eletroforese Capilar , Humanos , Reprodutibilidade dos Testes , Extração em Fase SólidaRESUMO
Circumventing the impact of agrochemicals on aquatic environments has become a necessity for health and ecological reasons. Herein, we report the use of a family of five eco-friendly water-stable isoreticular metal-organic frameworks (MOFs), prepared from amino acids, as adsorbents for the removal of neonicotinoid insecticides (thiamethoxam, clothianidin, imidacloprid, acetamiprid, and thiacloprid) from water. Among them, the three MOFs containing thioether-based residues show remarkable removal efficiency. In particular, the novel multivariate MOF {SrIICuII6[(S,S)-methox]1.5[(S,S)-Mecysmox]1.50(OH)2(H2O)}·36H2O (5), featuring narrow functional channels decorated with both -CH2SCH3 and -CH2CH2SCH3 thioalkyl chains-from l-methionine and l-methylcysteine amino acid-derived ligands, respectively-stands out and exhibits the higher removal efficiency, being capable to capture 100% of acetamiprid and thiacloprid in a single capture step under dynamic solid-phase extraction conditions-less than 30 s. Such unusual combination of outstanding efficiency, high stability in environmental conditions, and low-cost straightforward synthesis in 5 places this material among the most attractive adsorbents reported for the removal of this type of contaminants.
Assuntos
Inseticidas/isolamento & purificação , Estruturas Metalorgânicas/química , Neonicotinoides/isolamento & purificação , Sulfetos/química , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Cisteína/análogos & derivados , Cisteína/química , Inseticidas/química , Metionina/química , Neonicotinoides/química , Extração em Fase Sólida/métodos , Poluentes Químicos da Água/química , Purificação da Água/métodosRESUMO
A composite built with aminated zeolitic imidazolate framework and gold nanoparticles (AuNPs) for solid-phase extraction (SPE) of neonicotinoids in agricultural samples is presented. The composite was prepared through the assembly of AuNPs onto the surface of metal-organic framework based on the strong interaction between the amino group and AuNP. These metallic surfaces provided additional interactions based on the affinity of amino and cyano groups present in the target compounds. The composite was characterized by scanning electron microscopy, powder X-ray diffraction, Fourier-transform infrared spectroscopy, and surface area measurements. Regarding the SPE protocol, several parameters that can influence the extraction performance were optimized, such as sample volume or composition of elution solvent, among others. After elution, the analytes were determined via HPLC with diode-array detection. Under the selected conditions, satisfactory recoveries of five pesticides (thiamethoxan, clothianidin, imidacloprid, acetamiprid, and thiacloprid) were obtained (between 80 and 110%) in real samples, whereas the limits of detection ranged from 0.019 to 0.041 µg L-1 in aqueous samples and 0.3 to 0.8 µg g-1 in solid samples.
Assuntos
Nanopartículas Metálicas/química , Estruturas Metalorgânicas/química , Neonicotinoides/isolamento & purificação , Resíduos de Praguicidas/isolamento & purificação , Extração em Fase Sólida/métodos , Agave/química , Cromatografia Líquida de Alta Pressão , Contaminação de Alimentos/análise , Ouro/química , Imidazóis/química , Limite de Detecção , Neonicotinoides/análise , Resíduos de Praguicidas/análise , Reprodutibilidade dos Testes , Poluentes do Solo/análise , Poluentes do Solo/isolamento & purificação , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/isolamento & purificação , Zeolitas/químicaRESUMO
This paper describes the fabrication of a novel microbore monolithic column modified with magnetite nanoparticles (MNPs) prepared in a poly(ethylene-co-tetrafluoroethylene) (EFTE) tubing, and its application as stationary phase for the chromatographic separation of phosphorylated compounds. In order to obtain the composite column, a two-step procedure was performed. The formation of a glycidyl methacrylate-based monolith inside the activated ETFE tube was firstly carried out. Then, two incorporation approaches of MNPs in monoliths were investigated. The generic polymer was modified with 3-aminopropyltrimethoxysilane (APTMS) to be subsequently attached to MNP surfaces. Alternatively, APTMS-coated MNPs were firstly prepared and subsequently used for attachment onto the monolith surface through reaction of epoxy groups present in the generic monolith. This last strategy gave a reproducible layer of MNPs coated onto the polymer monolith as well as robust and permeable chromatographic columns. The retention behaviour of this MNP-based composite monolithic column was studied by using small phosphorylated compounds (adenosine phosphates). It was found that the retention of model analytes was ruled by partitioning and adsorption HILIC mechanisms. The columns also exhibited satisfactory performance in the separation of these target compounds, showing good chromatographic behaviour after two months of continued use. These composite monolithic columns were also successfully applied to the extraction of a tryptic digest of ß-casein.
RESUMO
In this work, the synthesis of zeolitic imidazolate framework-8 (ZIF-8) crystals and their subsequent application as effective sorbents for extraction and preconcentration of several benzomercaptans from environmental complex samples is described. These materials were prepared by solvothermal approach varying the concentration of n-butylamine modulator to modify the surface of the metal-organic framework. The resulting materials were characterized by scanning and transmission electron microscopy, powder X-ray diffraction and Fourier transform infrared spectroscopy. The ZIF-8 material that gave the best features was selected as extractive phase and the influence of various parameters (sample pH and elution solvent composition, among others) on the extraction efficiency of target compounds were investigated. Under the optimal conditions of the method, the tested analytes (2-mercaptobenzothiazole, 2-mercaptobenzoxazole and 2-mercapto-6-nitrobenzothiazole) were retained and eluted quantitatively with alkaline 50:50 (v:v) methanol-water mixture. Using the proposed method, low limits of detection, in the range of 16-21 ng L-1 for aqueous samples and 0.4-0.5 µg kg-1 for soil samples, were achieved whereas the precision (expressed as relative standard deviation) was lower than 7%. The resulting solid-phase extraction protocol, using the zeolitic material as sorbent, was combined with liquid chromatography and ultraviolet-vis detector and successfully applied to determine traces of these organic pollutants in environmental samples.
Assuntos
Estruturas Metalorgânicas , Poluentes Químicos da Água , Zeolitas , Cromatografia Líquida de Alta Pressão , Extração em Fase Sólida , Poluentes Químicos da Água/análiseRESUMO
This review summarizes the recent advances concerning metal-organic frameworks (MOFs) modified with several biomolecules (e.g., amino acids, nucleobases, proteins, antibodies, aptamers, etc.) as ligands to prepare affinity-based sorbents for application in the sample preparation field. The preparation and incorporation strategies of these MOF-based affinity materials were described. Additionally, the different types of ligands that can be employed for the synthesis of these biocomposites and their application as sorbents for the selective extraction of molecules and clean-up of complex real samples is reported. The most important features of the developed biocomposites will be discussed throughout the text in different sections, and several examples will be also commented on in detail.
Assuntos
Química/métodos , Química/tendências , Ligantes , Estruturas Metalorgânicas/química , Proteínas/química , Adsorção , Materiais Biocompatíveis , Biomimética , Carboidratos/química , Humanos , Microscopia Eletrônica de Varredura , Fenômenos Físicos , Polímeros/química , Ligação Proteica , Proteômica , Extração em Fase SólidaRESUMO
An in situ preparation of metal-organic framework (HKUST-1) on the surface of an organic polymer is reported. The hybrid material was evaluated as sorbent for solid-phase extraction (SPE) of oxygenated and nitrated polycyclic aromatic hydrocarbons (PAHs). The growth of HKUST-1 on MAA-based polymer was accomplished using a layer-by-layer assembly strategy. The HKUST-1-polymer was characterized using powder X-ray diffraction and scanning electron microscopy to demonstrate the incorporation of MOF crystals onto the polymer surface. The MOF (nano)crystals were characterized using high-resolution transmission electron microscopy and high-angle annular-dark-field scanning transmission electron microscopy. The water-stable MOF-polymer was evaluated as SPE sorbent, and several variables that can influence the extraction recoveries of PAH derivatives were investigated. Under the selected conditions, the detection limits varied between 4 and 21 ng·L-1, and the precision (relative standard deviation) was below 12%. The recovery values for spiked solutions ranged from 95 to 104%, and the enrichment factor achieved was close to 1000-fold using a high sample volume (100 mL) and very low desorption volume (100 µL). The SPE enrichment combined with HPLC and DAD detector was successfully applied to the extraction and determination of polycyclic hydrocarbons in environmental water samples. Graphical abstract A layer-by-layer synthesis of HKUST-1 onto polymer surface was performed and applied to isolation of PAH derivatives in environmental water samples.
RESUMO
A glycidyl methacrylate-based monolith was modified with imidazolium-based ionic liquid (IL) to be used as stationary phase for solid-phase extraction (SPE). The host monolithic support was prepared by in-situ UV polymerization in spin column format. Two approaches were developed to incorporate the IL into the polymeric monolithic matrix: generation of IL onto the surface monolith, and copolymerization by addition of the IL to the polymerization mixture, which gave the best results. The resulting sorbent materials were morphologically characterized and used for the isolation of five ß-blockers from human urine samples. All SPE steps were accomplished by centrifugation, which reduces significantly costs and time in sample treatment. Under optimal conditions, ß-blockers were quantitatively retained in the modified monolith at pH 12, and desorbed with a water-methanol mixture, to be subsequently determined via HPLC with UV detection. The limits of detection ranged between 1.4 and 40 µg L-1, and the reproducibility among extraction units (expressed as relative standard deviation) was below 8.2%. The novel phase was successfully applied to the extraction of propranolol in urine samples with recoveries above 90%.
Assuntos
Antagonistas Adrenérgicos beta/isolamento & purificação , Compostos Alílicos/química , Compostos de Epóxi/química , Imidazóis/química , Metacrilatos/química , Polímeros/química , Extração em Fase Sólida , Antagonistas Adrenérgicos beta/química , Antagonistas Adrenérgicos beta/urina , Humanos , Tamanho da Partícula , Propriedades de SuperfícieRESUMO
A bio-metal-organic framework (bio-MOF) derived from the amino acid L-serine has been prepared in bulk form and evaluated as sorbent for the molecular recognition and extraction of B-vitamins. The functional pores of bio-MOF exhibit high amounts of hydroxyl groups jointly directing other supramolecular host-guest interactions thus providing the recognition of B-vitamins in fruit juices and energy drinks. Single-crystal X-ray diffraction studies reveal the specific B-vitamin binding sites and the existence of multiple hydrogen bonds between these target molecules and the framework. It offered unique snapshots to accomplish an efficient capture of these solutes in complex aqueous matrices. Four B-vitamins (thiamin, nicotinic acid, nicotinamide, and pyridoxine) were investigated. They were eluted from the sorbent with phosphate buffer at pH 7 and analyzed by HPLC with UV detection. The sorbent was compared with commercial C18 cartridges. Following the procedure, acceptable reproducibility (RSD values < 14%) was achieved, and the detection limits were in the range 0.4 to 1.4 ng mL-1. The method was applied to the analysis of energy drink and juice samples and the recoveries were between 75 and 123% in spiked beverage samples. Graphical abstractA bio-MOF as SPE sorbent was prepared and applied to the extraction of B-vitamins in fruit juices and energy drinks.
Assuntos
Estruturas Metalorgânicas/química , Complexo Vitamínico B/isolamento & purificação , Adsorção , Interações Hidrofóbicas e Hidrofílicas , Tamanho da Partícula , Propriedades de Superfície , Raios Ultravioleta , Complexo Vitamínico B/químicaRESUMO
In this work, a simple device for extraction glutathione (GSH) in biological fluids using a hybrid monolithic material within a polypropylene syringe is developed. For this purpose, glycidyl methacrylate-based monolith was firstly prepared within this housing material, and the polymer was modified with different ligands (ammonia, cysteamine and cystamine). The resulting materials (containing amine or thiol groups, respectively) were then functionalized with gold nanoparticles (AuNPs). The hybrid material that gave the largest AuNPs coverage was selected as solid-phase (SPE) sorbent and several variables affecting the extraction recovery of this compound were investigated. Under optimal conditions, GSH was quantitatively retained at pH 6.0, and then it was desorbed with aqueous dithiothreitol solution and determined, after derivatization with o-phthaldialdehyde, via reversed-phase LC with fluorometric detection. The limit of detection was ca. 1.5 ng mL-1, and the reproducibility between extraction units was below 8% (expressed as relative standard deviation), which demonstrates the robustness of the method. The developed material was also applied for the extraction of GSH in saliva and urine samples yielding recoveries ranging from 86 to 105%.
Assuntos
Glutationa/isolamento & purificação , Ouro/química , Nanopartículas Metálicas/química , Extração em Fase Sólida/métodos , Cromatografia Líquida de Alta Pressão/métodos , Compostos de Epóxi/química , Glutationa/análise , Glutationa/urina , Humanos , Limite de Detecção , Metacrilatos/química , Reprodutibilidade dos Testes , Saliva/química , SeringasRESUMO
A (glycidyl methacrylate)-co-(ethylene glycol dimethacrylate) polymer (poly(GMA-co-EDMA)) was functionalized with metal-organic frameworks (MOF) and used as a sorbent for solid-phase extraction (SPE). The polymeric sorbent was prepared in-situ by photopolymerization in a previously wall-modified spin column, and then modified with an amino-modified MOF of type NH2-MIL-101(Cr). The sorbents were used for the extraction of nonsteroidal anti-inflammatory drugs (NSAIDs) from human urine samples. The sorbent was compared with the parent monolith and embedded approach, where the MOF particles are admixed in the polymerization mixture before the in-situ polymerization in the modified spin column. SPE is performed by percolating the sample solutions in a centrifuge, which streamlines the SPE steps. The hybrid composites were characterized by scanning electron microscopy and nitrogen intrusion porosimetry. Three NSAIDs (ketoprofen, flurbiprofen, and ibuprofen) were tested. They were eluted from the sorbent with acidified water-acetonitrile mixtures and subsequently analyzed by reversed-phase HPLC with UV detection. The detection limits varied in the range from 0.1 to 7 µg·L-1, and the precisions (relative standard deviation) were <14% in all the cases. The recoveries were between 71.0 and 78.0% in spiked urine samples. Graphical abstractA hybrid monolith modified with amino-modified MOF [named NH2-MIL-101(Cr)] in wall-modified spin columns was prepared. The resulting micro-extraction device was applied to the extraction and preconcentration of non-steroidal anti-inflammatory drugs.
Assuntos
Anti-Inflamatórios não Esteroides/isolamento & purificação , Flurbiprofeno/isolamento & purificação , Ibuprofeno/isolamento & purificação , Cetoprofeno/isolamento & purificação , Estruturas Metalorgânicas/química , Microextração em Fase Sólida/métodos , Adsorção , Anti-Inflamatórios não Esteroides/química , Anti-Inflamatórios não Esteroides/urina , Cromatografia Líquida de Alta Pressão , Cromatografia de Fase Reversa , Flurbiprofeno/química , Flurbiprofeno/urina , Humanos , Ibuprofeno/química , Ibuprofeno/urina , Cetoprofeno/química , Cetoprofeno/urina , Limite de Detecção , Metilmetacrilatos/químicaRESUMO
Metal-organic frameworks consisting of amino-modified MIL-101(M: Cr, Al, and Fe) crystals have been synthesized and subsequently incorporated to glycidyl methacrylate monoliths to develop novel stationary phases for nano-liquid chromatography. Two incorporation approaches of these materials in monoliths were explored. The metal-organic framework materials were firstly attached to the pore surface through reaction of epoxy groups present in the parent glycidyl methacrylate-based monolith. Alternatively, NH2 -MIL-101(M) were admixed in the polymerization mixture. Using short time UV-initiated polymerization, monolithic beds with homogenously dispersed metal-organic frameworks were obtained. The chromatographic performance of embedded UV-initiated composites was demonstrated with separations of polycyclic aromatic hydrocarbons and non-steroidal anti-inflammatory drugs as test solutes. In particular, the incorporation of the NH2 -MIL-101(Al) into the organic polymer monoliths led to an increase in the retention of all the analytes compared to the parent monolith. The hybrid monolithic columns also exhibited satisfactory run-to-run and column-to-column reproducibility.
RESUMO
In this study, mesoporous silica materials (MSMs) with bimodal pore systems (namely, UVM-7), MCM-41 silica, and a commercial silica-based material were evaluated as solid-phase extraction (SPE) sorbents for the isolation of phospholipids (PLs) using phosphatidylcholine as a test compound. Morphological characterization (including TEM, surface, and size pore measurements) of these materials was carried out. The mechanism of interaction of the target analyte with the MSMs was also studied. With regard to the SPE process, several experimental parameters that affect the extraction performance (e.g., loading and elution solvent, breakthrough volume, loading capacity, and reusability) were investigated. The recommended protocol was applied to the extraction of PLs in human milk fat samples. The extracted PLs were then determined by hydrophilic interaction liquid chromatography (HILIC) using evaporative light scattering detection (ELSD). This work reports the first application of silica-based mesoporous materials to preconcentrate PLs in these complex matrices. Graphical abstract á .
Assuntos
Leite Humano/química , Fosfolipídeos/isolamento & purificação , Dióxido de Silício/química , Extração em Fase Sólida/métodos , Cromatografia Líquida/métodos , Humanos , Interações Hidrofóbicas e Hidrofílicas , Fosfolipídeos/análise , PorosidadeRESUMO
This work evaluates the potential of methacrylate monoliths with multi-walled carbon nanotubes incorporated into the polymeric network for the extraction of antidepressants from human urine. The method is based on a micropipette solid-phase extraction tip containing a hybrid monolithic material covalently attached to the polypropylene housing. A polymer layer made from poly(ethylene dimethacrylate) was bound to the inner surface of a polypropylene tip via UV grafting. The preparation of the monolith and the microextraction steps were optimized in terms of adsorption capacity. Limits of detection ranged from 9 to 15 µg·L-1. The average precision of the method varied between 3 and 5% (intra-tips), and from 4 to 14% (inter-tips). The accuracy of the method was evaluated through a recovery study by using spiked samples. Graphical abstract Hybrid polymer monoliths containing multi-walled carbon nanotubes (MWCNTs) were prepared in pipette tips by photo-polymerization approach. The extraction devices were used for the extraction of antidepressants in urine samples.
Assuntos
Antidepressivos/isolamento & purificação , Nanotubos de Carbono/química , Ácidos Polimetacrílicos/química , Microextração em Fase Sólida/métodos , Adsorção , Antidepressivos/urina , Desenho de Equipamento , Humanos , Limite de DetecçãoRESUMO
A complete characterization of the proteome of seminal plasma (SP) is an essential step to understand how SP influences sperm function and fertility after artificial insemination (AI). The purpose of this study was to identify which among characterized proteins in boar SP were differently expressed among AI boars with significantly different fertility outcomes. A total of 872 SP proteins, 390 of them belonging specifically to Sus Scrofa taxonomy, were identified (Experiment 1) by using a novel proteomic approach that combined size exclusion chromatography and solid-phase extraction as prefractionation steps prior to Nano LC-ESI-MS/MS analysis. The SP proteomes of 26 boars showing significant differences in farrowing rate (n = 13) and litter size (n = 13) after the AI of 10â¯526 sows were further analyzed (Experiment 2). A total of 679 SP proteins were then quantified by the SWATH approach, where the penalized linear regression LASSO revealed differentially expressed SP proteins for farrowing rate (FURIN, AKR1B1, UBA1, PIN1, SPAM1, BLMH, SMPDL3A, KRT17, KRT10, TTC23, and AGT) and litter size (PN-1, THBS1, DSC1, and CAT). This study extended our knowledge of the SP proteome and revealed some SP proteins as potential biomarkers of fertility in AI boars.
Assuntos
Fertilidade/genética , Tamanho da Ninhada de Vivíparos/genética , Proteoma/genética , Sêmen/fisiologia , Animais , Biomarcadores/metabolismo , Cromatografia em Gel , Feminino , Expressão Gênica , Perfilação da Expressão Gênica , Ontologia Genética , Inseminação Artificial , Masculino , Anotação de Sequência Molecular , Proteoma/metabolismo , Sêmen/química , Análise do Sêmen , Extração em Fase Sólida/métodos , Espectrometria de Massas por Ionização por Electrospray , Motilidade dos Espermatozoides/fisiologia , Espermatozoides/citologia , Espermatozoides/fisiologia , SuínosRESUMO
A polymethacrylate-based sorbent modified with magnetic nanoparticles (MNPs) has been synthesized and used as sorbent for solid-phase extraction (SPE) and magnetic solid-phase extraction (MSPE) of three organophosphorus pesticides (phosmet, pirimiphos-methyl, and chlorpyrifos) in water samples followed by high-performance liquid chromatography-diode array detection. The sorbent was prepared from a glycidyl methacrylate-based polymer, modified with a silanizing agent, followed by immobilization of MNPs on the surface of the material. The sorbent was characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. Comparative studies of this support were done both in conventional SPE cartridge and MSPE approach. Several extraction parameters (loading pH, elution solvent, eluting volume, and loading flow rate) were investigated in detail. Under optimal conditions, the proposed sorbent gave an excellent enrichment efficiency of analytes and detection limits between 0.01 and 0.25 µg L-1. The recoveries of organophosphorus pesticides in spiked water samples were in the range of 71-98%, and the developed sorbent showed a high reusability (up to 50 uses without losses in recovery). The proposed method was satisfactorily applied to the analysis of these pesticides in water samples from different sources.
RESUMO
A method for the simultaneous determination of the most frequently used surfactant families -linear alkyl benzenesulphonates (LAS), alkyl ether sulphates (AES), fatty alcohol ethoxylates (FAE) and oleins (soaps, fatty acid salts) - in cleaning products, has been developed. The common reversed phase octyl (C8), pentafluorophenyl and biphenyl columns were not capable of separating the anionic LAS and AES classes; however, since only LAS absorbs in the UV, these two classes were independently quantified using a C8 column and serially connected UV and ELSD detection. The best compromise to resolve the four surfactant classes and the oligomers within the classes was achieved with a C8 column and an ACN/water gradient. To enhance retention of the anionic surfactants, ammonium acetate, as an ion-pairing agent compatible with ELSD detection, was used. Also, to shift the olein peaks with respect to that of the FAE oligomers, acetic acid was used. In the optimized method, modulation of the mobile phase, using ammonium acetate during elution of LAS and AES, and acetic acid after elution of LAS and AES, was provided. Quantitation of the overlapped LAS and AES classes was achieved by using the UV detector to quantitate LAS and the ELSD to determine AES by difference. Accuracy in the determination of AES was achieved by using a quadratic model, and by correcting the predicted AES concentration according to the LAS concentration previously established using the UV chromatogram. Another approach also leading to accurate predictions of the AES concentration was to increase the AES concentrations in the samples by adding a standard solution. In the samples reinforced with AES, correction of the predicted AES concentration was not required. FAE and olein were quantified using also quadratic calibration.
RESUMO
Combinatorial peptide ligand library technology, coupled to mass spectrometry, has been applied to extensively map the proteome of orange pulp and peel and, via this fingerprinting, to detect its presence in commercial orange juices and drinks. The native and denaturing extraction protocols have captured 1109 orange proteins, as identified by LC-MS/MS. This proteomic map has been searched in an orange concentrate, from a Spanish juice manufacturer, as well as in commercial orange juices and soft drinks. The presence of numerous orange proteins in commercial juices has demonstrated the genuineness of these products, prepared by using orange fruits as original ingredients. However, the low number of identified proteins in sparkling beverages has suggested that they were prepared with scarce amounts of fruit extract, thus imparting lower quality to the final products. These findings not only increase the knowledge of the orange proteome but also present a reliable analytical method to assess quality and genuineness of commercial products.