1,720,973 research outputs found
Veterinary drugs residues: a review of the latest analytical research on sample preparation and LC-MS based methods
No full textThe world population is increasing and there is a growing demand for food, leading to intensification of farming methods and a requirement for more coadjuvants. Potential high profits sometimes lead to fraudulent use of drugs and pesticides. Veterinary drugs in particular can pose a real risk to human health if their residues are allowed to enter the food chain. Parent drugs and their metabolites can occur in foodstuffs individually or as multicomponent mixtures with enhanced adverse effects. In order to protect consumer safety, the European Union has established lists of forbidden substances, maximum residue limits for authorised drugs and precise criteria for confirmation analyses and interpretation of the results. Due to their nature and potential danger, the ‘best available technique’ should always be applied. Following this principle, this review examines the procedures and techniques applied to monitoring pharmaceutical products of major concern (e.g. anthelmintics, NSAIDs, corticosteroids, coccidiostats) in foods of animal origin, discussing advances over the past five years and future trends in the field of food safety. Our goal was both to focus attention on this important topic and to provide a selection of the most relevant recent papers on drug residues in foodstuffs. © 2017 Informa UK Limited, trading as Taylor & Francis Group
Dispersive liquid-liquid microextraction using a low transition temperature mixture and liquid chromatography-mass spectrometry analysis of pesticides in urine samples
No full textBiomonitoring is a potent tool to control the health risk of people occupationally and non-occupationally exposed. The latest trend in bioanalytical chemistry is to develop quick, cheap, easy, safe and reliable green analytical procedures to analyse a large number of chemicals in easily accessible biomatrices such as urine. In this paper, a new dispersive liquid–liquid microextraction (DLLME) procedure, conceived to treat urine samples and based on the use of a low transition temperature mixture (LTTM), was developed and validated to analyse twenty pesticides commonly used in farm practises. The LTTM was composed of choline chloride and sesamol in molar ratio 1:3 (ChCl:Ses 1:3); its characterization via differential scanning calorimetry identified it as an LTTM and not as a deep eutectic solvent due to the occurrence of a glass transition at -71 °C. The prepared mixture was used as the extraction solvent in the DLLME procedure, while ethyl acetate as the dispersing solvent. The salting out effect (50 mg mL−1 of NaCl in a diluted urine sample) improved the separation phase and the analyte transfer to the extractant. Due to the high ionic strength and despite the density of ChCl:Ses 1:3 (1.25 g mL−1), the LTTM layer floated on the top of the sample solution after centrifugation. All extracts were analysed by high-performance liquid chromatography coupled to mass spectrometry. After optimization and validation of the whole method, lower limits of quantitation were in the range of 0.02 – 0.76 μg L−1. Extraction recoveries spanned from 50 to 101 % depending on the spike level and analytes. Precision and accuracy ranges were 3-18% and 5-20%, respectively. The extraction procedure was also compared with other methods, showing to be advantageous for rapidity, simplicity, efficiency, and low cost. Finally, urine samples from ten volunteers were effectively analysed using the developed method
Supercritical fluid chromatography for vitamin and carotenoid analysis: an update covering 2011-2021
Full text linkAs it is known, the chromatographic separations of vitamins is not a trivial issue. The subtle heterogeneity among homologs belonging to the same group makes it difficult to perform their speciation. On the other hand, differences in terms of structure complicate the simultaneous analysis of the main forms belonging to the several vitamin groups. Long times of analysis as well as the use of conventional toxic organic solvents, such as hexane and MeOH, are other downsides of conventional methods based on liquid chromatography. Over the last few years, Ultra-Performance Convergence Chromatography (UPCC or UPC2) has emerged as a unique separation technique for its green character and the unparalleled ability to achieve chiral and achiral separations with an unequalled speed and reproducibility. Conceived after 2010, UPCC merges the advantages of the conventional supercritical fluid chromatography (SFC) with those of the ultra-high performance liquid chromatography (UHPLC) technology. Its application to vitamin and carotenoid analysis has shown a potential in solving the above-mentioned issues, which is still untapped. This review offers a comprehensive perspective of the SFC advancements in the last ten years and the advantages that arise from its application in vitamin and carotenoid analysis. Compared to conventional techniques, the flexibility of UPCC is unique, making it possible the simultaneous analysis of different group of achiral and chiral vitamins within the same short chromatographic run
Anatomy of a deep eutectic solvent: structural properties of choline chloride : sesamol 1 : 3 compared to reline
No full textThe structural properties of the deep eutectic solvent (DES) formed by choline chloride (ChCl) and sesamol in 1 : 3 ratio have been investigated and compared to those of reline (ChCl : urea 1 : 2). An integrated approach combining small and wide angle X-ray scattering with molecular dynamics simulations has been employed and the simulation protocol has been validated against the experimental data. In the ChCl : sesamol DES, strong hydrogen bonds (HBs) are formed between the chloride anion and the hydroxyl groups of the choline and of sesamol molecules. Conversely, choline-choline, choline-sesamol and sesamol-sesamol interactions are negligible. A more extended interplay between the constituents is observed in reline where, besides the HBs involving the chloride anion, the eutectic formation is favored also by strong choline-urea and urea-urea interactions. The three-dimensional arrangement around the individual components shows that, in the ChCl : sesamol DES, the cholinium cations and the sesamol molecules are packed in such a way to maximize the interactions with the chlorine anion. This structural arrangement may favor the pi-pi interactions between the sesamol molecules and the aromatic species mediated by the chloride ions, providing an interpretation for the high separation rates previously observed for phenolic DESs towards aromatic compounds
Liquid chromatography-tandem mass spectrometry method for the determination of vitamin K homologues in human milk after overnight cold saponification
No full textHuman milk is the only source of vitamin K for exclusively breastfed neonates. This vitamin is crucial both for blood coagulation (vitamin K1) and for the normal neurological and skeletal development of the foetus and newborn (vitamin K2). Since vitamin K is ubiquitous in foods, deficiency is not common in adults, but plasma levels and hepatic storage are very low at birth. In light of the importance of this valuable micronutrient, a non-invasive method for verifying that exclusively breastfed infants are receiving an adequate supply of the vitamin is clearly a topic of great significance. In spite of this, the determination of the several vitamin K homologues in human milk has still not been completely elucidated. This paper presents an HPLC-MS/MS method for the simultaneous determination of phylloquinone, menaquinone-4 (MK-4), and menaquinone-7 (MK-7) in human milk after a simple and effective isolation procedure. Overnight cold saponification and extraction of the analytes with hexane provided yields above 75%. This procedure, combined with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), made it possible to achieve limits of detection (LODs) below 0.8ng/mL. After a complete validation study, the method was applied to measure vitamin K congeners in several human milk samples; results showed vitamin K1 concentrations comparable with those reported in the literature. In addition, this is the first study performed for the determination of MK-4 and MK-7 in the maternal milk of Italian women
Multi-residue determination of organic micro-pollutants in river sediment by stir-disc solid phase extraction based on oxidized buckypaper
No full textThis paper describes a procedure for the isolation of 20 organic micro-pollutants among pesticides, drugs, recreational drugs, flame retardants from river sediments. After a solid-liquid extraction with a methanol:water (50:50, v/v) solution, the supernatant was diluted with water and cleaned up by stir-disc solid-phase extraction (SPE). The disc was made of buckypaper, a self-supporting entangled assembly of carbon nanotubes, which was used as a highly porous, two-sided, sorbent membrane. In the preliminary activation step, the membrane was oxidised for 2-hours with nitric acid to extend its extraction capability also to more polar compounds. All extracts were analysed by ultra-high-performance liquid chromatography-tandem mass spectrometry. A comparative investigation with commercial Strata-X Polymeric Reversed Phase SPE cartridges proved the effectiveness of the lab-made device. On the average, the analytes were recovered with yields around 69% (low spike level) and 80% (medium and high spike level), while only a couple of analytes exhibited values less than 50%. The relative standard deviation was always less than 20%. Limits of detections were in the range 0.02–9.9 ng g−1. The validated method was then applied for the analysis of sediment samples from different sites of the River Turia basin in the area of Valencia (Spain), finding tris(2-chloroisopropyl)-phosphate in all sediments at a level ranging from 6.9 to 387.9 ng g−1. Other compounds, such as pesticides and pharmaceuticals were more sporadically in these samples.This work has been supported by the Generalitat Valenciana through the project ANTROPOCEN@ (PROMETEO/2018/155).Peer reviewe
Fate of a deep eutectic solvent upon cosolvent addition: choline chloride-sesamol 1:3 mixtures with methanol
Full text linkThe changes upon methanol (MeOH) addition in the structural arrangement of the highly eco-friendly deep eutectic solvent (DES) formed by choline chloride (ChCl) and sesamol in 1:3 molar ratio have been studied by means of attenuated total reflection Fourier transform infrared spectroscopy, small- and wide-angle X-ray scattering (SWAXS), and molecular dynamics simulations. The introduction of MeOH into the DES promotes the increase of the number of Cl–MeOH hydrogen bonds (HBs) through the replacement of sesamol and choline molecules from the chloride anion coordination sphere. This effect does not promote the sesamol–sesamol, choline–choline, and sesamol–choline interactions, which remain as negligible as in the pure DES. Differently, the displaced sesamol and choline molecules are solvated by MeOH, which also forms HBs with other MeOH molecules, so that the system arranges itself to keep the overall amount of HBs maximized. SWAXS measurements show that this mechanism is predominant up to MeOH/DES molar ratios of 20–24, while after this ratio value, the scattering profile is progressively diluted in the cosolvent background and decreases toward the signal of pure MeOH. The ability of MeOH to interplay with all of the DES components produces mixtures with neither segregation of the components at nanoscale lengths nor macroscopic phase separation even for high MeOH contents. These findings have important implications for application purposes since the understanding of the pseudophase aggregates formed by a DES with a dispersing cosolvent can help in addressing an efficient extraction procedure
Recent advancements and future trends in environmental analysis: sample preparation, liquid chromatography and mass spectrometry
No full textAmong the thousands of chemicals having potential to enter the environment, the NORMAN network has identified at least 700 substances categorized into 20 classes in the European surface waters. Pesticides, pharmaceuticals, disinfection by-products, wood preservation and industrial chemicals are the prominent classes. Since the impact of these substances on aquatic life and human health might be dramatic, action is urgently required at multiple levels; one of them is just related to the development of more and more sensible and selective analytical methods.
This review highlights the latest advancements and trends in liquid chromatographye-mass spectrometry based environmental analysis. Specific sections are dedicated to novelties in sample preparation, chromatographic separation and mass spectrometry detection of emerging pollutants. The review also offers insights on last generation chromatographic and extraction materials, technological progresses and innovative methodological approaches for target and non-target analysis. As numerous papers have been published in this field, this overview covers the most representative and original works published in the 2011-2016 period. (C) 2017 Elsevier B.V. All rights reserved
Oxidized buckypaper for stir-disc solid phase extraction: evaluation for several classes of environmental pollutants recovered from surface water samples
No full textThis paper describes, for the first time, the use of oxidized buckypaper (BP) as a sorbent membrane of a stir-disc solid phase extraction module. The original device, consisting of a BP disc (d = 34 mm) enveloped in a polypropylene mesh pouch, was designed to extract organic micropollutants (OMPs) from environmental water samples in dynamic mode. High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was used to analyze the extracts. Several classes of pesticides and pharmaceuticals were chosen as model compounds to evaluate key parameters affecting the recovery rates. To this end, the effects of adsorption time, desorption time, stirring speed, type and volume of solvent, and sample volume were thoroughly examined. After optimization, a novel and in-depth study was conducted to find a correlation between physicochemical properties of the analytes and extraction yields. Recoveries were mainly governed by a combination of logP and pK a values. As indicated, hydrophilic compounds with logP 1 exhibited recoveries ranging between 50% and 100% depending on their pK a , while compounds with pK a between 6 and 7.5 gave low yields irrespective of their logP. The analytical method was also validated and tested as large scale screening method of OMPs in surface waters. The analysis of real samples revealed the presence of some nonsteroidal anti-inflammatory drugs, sulfonamides, and pesticides at low ng L -1 concentration levels with relative standard deviations lower than 8%. Copyright © 2018 American Chemical Society
Determination of target fat-soluble micronutrients in rainbow trout's muscle and liver tissues by liquid chromatography with diode array-tandem mass spectrometry detection
No full textThis paper describes an analytical approach, based on LC-diode array detector-MS/MS (LC-DAD-MS/MS), for characterizing the fat-soluble micronutrient fraction in rainbow trout (Oncorhynchus mykiss). Two different procedures were applied to isolate the analytes from liver and muscle tissue: overnight cold saponification to hydrolyze bound forms and to simplify the analysis; matrix solid-phase dispersion to avoid artifacts and to maintain unaltered the naturally occurring forms. Analytes were separated on a C30 analytical column by using a nonaqueous reversed mobile phase compatible with the atmospheric pressure chemical ionization. Compared to other works, the most relevant advantage of the here illustrated method is the large amount of information obtained with few analytical steps: nine fat-soluble vitamins (3,4-dehydroretinol, retinol, cholecalciferol, ergocalciferol, α-tocopherol, γ-tocopherol, δ-tocopherol, phylloquinone, and menaquinone-4) and eight carotenoids (all-trans-lutein, all-trans-astaxanthin, all-trans-zeaxanthin, all-trans-β-cryptoxanthin, all-trans-canthaxanthin, all-trans-ζ-carotene, all-trans-β-carotene, and all-trans-γ-carotene) were quantified after the method validation, while other untargeted carotenoids were tentatively identified by exploiting the identification power of the LC-DAD-MS/MS hyphenation
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