•A method for simultaneous determination of nine β-lactams in ewe milk using HPLC-DAD is described.•Sample treatment allowed extracts ready for fast identification and quantification.•Analyte ...recoveries ranged from 79% to 96% with relative standard deviations between 0.5% and 4.9%.•LOQs were 3.4–8.6μgkg−1, lower than MRLs established by the European Union.•A powerful and popular tool for confirmation of antibiotics in small milk industries is described.
The presence of β-lactam residues in foodstuffs constitutes a potential risk to the human health and undesirable effects on consumers, and nowadays these antibiotic residues are also recognised as an emerging environmental problem. In addition, these are of great concern to prestigious Manchego cheese processors (Central Spain denomination of origin) because they reduce the curdling of milk and cause improper cheese ripening, which consequently lead to an important loss of monetary income.
This work describes the development of a sensitive and reliable method using liquid chromatography with UV-diode array detection (LC-DAD) for simultaneous determination of the β-lactam antibiotics, ampicillin (AMP), benzylpenicillin (PEG), cephalexin (CFX), cefazolin (CFL), cefoperazone (CFP), cloxacillin (CLO), dicloxacillin (DCL), oxacillin (OXA) and phenoxymethylpenicillin (PEV), in Manchega ewe milk. The column, mobile phase, temperature and flow rate were optimised to provide the best resolution of these analytes. The extraction method of the antibiotic residues involves the deproteinisation of the milk sample using acetonitrile and centrifugation followed by a solid-phase extraction (SPE) clean-up. The recoveries for the studied β-lactams ranged from 79% to 96% with relative standard deviations between 0.5% and 4.9%. The limits of quantification (LOQs) for all these compounds were in the range of 3.4–8.6μgkg−1, which are lower than the maximum residue limits (MRLs) established by the European Union for the studied β-lactams in milk, making the method suitable for performing routine analyses.
The proposed multi-residue LC-UV-diode array detection (LC-DAD) method is a powerful and popular alternative for the determination and confirmation of antibiotic residues in small milk industries and is the first one capable of determining nine β-lactam antibiotics in samples of Manchega ewe milk.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•A MISPE method has been used for selective preconcentration of AMP from cow milk.•HPLC with UV detection was used for the quantification of ampicillin.•MIPs have been synthetized and characterized ...by binding and FT-IR studies.•The method allows AMP determination in milk at concentrations required by legislation.
The aim of this study was to prepare molecularly imprinted polymers (MIPs) with ampicillin (AMP) and to evaluate the feasibility of these materials for being used as solid phase extraction sorbent for the selective preconcentration and determination of AMP in cow milk samples. MIPs were synthesized by bulk polymerization using methacrylic acid or methyl methacrylate as monomer and ethylene glycol dimethacrylate as cross-linker at different ratios. Characterization of the MIPs were carried out by Fourier-transform infrared spectrometry. The variables affecting the molecularly imprinted solid-phase extraction (MISPE) procedure were optimized. AMP recoveries were higher than 98%, and RSD less than 7%. A preconcentration factor of 20 was reached, which was sufficient to determine AMP at levels allowed by the EU (4μgkg−1) in cow milk. The selectivity of the AMP-MIP was evaluated in presence of other structurally related β-lactam antibiotics (amoxicillin, oxacillin, penicillin G).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The COHERENT experiment is well poised to test sub-GeV dark matter models using detectors sensitive to coherent elastic neutrino-nucleus scattering (CEvNS) in the π+ decay-at-rest (π-DAR) neutrino ...beam produced by the Spallation Neutron Source. We show a planned 750-kg single-phase liquid argon scintillation detector would place leading limits on scalar light dark matter models for dark matter particles produced through vector and leptophobic portals in the absence of other effects beyond the standard model. The characteristic timing profile of a π-DAR beam allows a unique opportunity for constraining systematic uncertainties on the standard model background using a time window where dark matter signal is not expected, enhancing expected sensitivity. Additionally, we discuss future prospects which show that an on-axis CEvNS detector would probe the thermal abundance for a scalar dark matter candidate for all couplings α′ ≤ 1 for 15 MeV dark matter with just 1.0 tonne-yr of exposure with increased exposure testing a wider range of dark matter masses and spins.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
We report the first measurement of coherent elastic neutrino-nucleus scattering (CEvNS) on argon using a liquid argon detector at the Oak Ridge National Laboratory Spallation Neutron Source. Two ...independent analyses prefer CEvNS over the background-only null hypothesis with greater than 3σ significance. The measured cross section, averaged over the incident neutrino flux, is (2.2±0.7)×10^{-39} cm^{2}-consistent with the standard model prediction. The neutron-number dependence of this result, together with that from our previous measurement on CsI, confirms the existence of the CEvNS process and provides improved constraints on nonstandard neutrino interactions.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UL, UM
•Synthesis of molecularly imprinted polymers by non-covalent bulk polymerization technique.•Characterization morphological and evaluation of binding capability of SPI-MIPs.•Imprinted solid phase ...extraction methodology for the analysis of spiramycin in milk samples.•Determination of spiramycin in sheep milk by liquid chromatography-UV diode-array detection.
A series of molecularly imprinted polymers (MIPs) comprising reactionary sites which are complementary to macrolide antibiotic spiramycin (SPI) were synthetized by noncovalent bulk polymerization technique. MIPs were synthesized under different polymerization process and their recognition efficiency was evaluated in binding studies in comparison with non-imprinted polymers. The best MIP was morphologically characterized and equilibrium assays were carried out. The MIP was evaluated as a sorbent for extraction and preconcentration of SPI from aqueous and sheep milk samples, and an off-line MISPE method followed by high-performance liquid chromatography with UV diode-array detection was established. Good linearity were obtained for SPI in a range of 24–965μgkg−1 and the average recoveries at three spiked levels in milk samples were higher than 90% (RSD<5%). Limit of quantification was 24.1μgkg−1. Cross-reactivity studies from other macrolides with similar structure were tested. The optimum imprinted polymer showed a good selectivity and affinity for SPI, demonstrating the potential of the proposed MISPE for rapid, sensitive and effective sample pretreatment for selective determination of SPI in sheep milk samples.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Space‐borne instruments can measure river water surface elevation, slope, and width. Remote sensing of river discharge in ungauged basins is far more challenging, however. This work investigates the ...estimation of river discharge from simulated observations of the forthcoming Surface Water and Ocean Topography (SWOT) satellite mission using a variant of the classical variational data assimilation method “4D‐Var.” The variational assimilation scheme simultaneously estimates discharge, river bathymetry, and bed roughness in the context of a 1.5 D full Saint‐Venant hydraulic model. Algorithms and procedures are developed to apply the method to fully ungauged basins. The method was tested on the Po and Sacramento Rivers. The SWOT hydrology simulator was used to produce synthetic SWOT observations at each overpass time by simulating the interaction of SWOT radar measurements with the river water surface and nearby land surface topography at a scale of approximately 1 m, thus accounting for layover, thermal noise, and other effects. SWOT data products were synthesized by vectorizing the simulated radar returns, leading to height and width estimates at 200 m increments along the river centerlines. The ingestion of simulated SWOT data generally led to local improvements on prior bathymetry and roughness estimates which allowed the prediction of river discharge at the overpass times with relative root mean squared errors of 12.1% and 11.2% for the Po and Sacramento Rivers, respectively. Nevertheless, equifinality issues that arise from the simultaneous estimation of bed elevation and roughness may prevent their use for different applications, other than discharge estimation through the presented framework.
Key Points
River discharge is estimated using synthetic remote sensing measurements from the forthcoming SWOT mission without any in situ observation
2D SWOT radar measurements are simulated and mapped onto river centerlines, producing realistic errors, temporal, and spatial sampling
Discharge accuracy was 12.1% and 11.2% on the Po and Sacramento Rivers, respectively, illustrating potential for ungauged basins
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Surface cooling induced by tropical cyclones (TCs) is about three times larger during premonsoon than during postmonsoon season in the Bay of Bengal. We investigate processes responsible for this ...seasonal contrast using an ocean general circulation model. The model is forced by TC winds prescribed from an analytic vortex using observed TC tracks and intensities during 1978–2007. The simulation accurately captures the seasonal cycle of salinity, temperature, and barrier layer in this region, with fresher waters, deeper upper‐ocean stratification, and thicker barrier layers during postmonsoon season. It also reproduces the three times larger TC‐induced cooling during premonsoon than during postmonsoon season. This difference is essentially related to seasonal changes in oceanic stratification rather than to differences in TC wind energy input. During the postmonsoon season, a deeper thermal stratification combined with a considerable upper‐ocean freshening strongly inhibits surface cooling induced by vertical mixing underneath TCs. On average, thermal stratification accounts for ∼60% of this cooling reduction during postmonsoon season, while haline stratification accounts for the remaining 40%. Their respective contributions however strongly vary within the Bay: haline stratification explains a large part of the TC‐induced cooling inhibition offshore of northern rim of the Bay (Bangladesh‐Myanmar‐east coast of India), where salinity seasonal changes are the strongest, while thermal stratification explains all the cooling inhibition in the southwestern Bay. This study hence advocates for an improved representation of upper‐ocean salinity and temperature effects in statistical and dynamical TCs forecasts that could lead to significant improvements of TC intensity prediction skill.
Key Points
TC‐induced cooling in Bay of Bengal is far weaker during post than pre‐monsoon
Thermal stratification changes account for ~70% of this cooling inhibition
Haline stratification explains most of cooling inhibition along Bay northern rim
► We have developed and validated a simple method to determine illegal dyes in sauces. ► Sample treatment allows to eliminate carothenoids and other interferences. ► Analyte recoveries were between ...60% and 99% and RSD ranging from 2.0% to 10.0%. ► LOD resulted five times lower than the values required by European regulations.
A fast, simple and effective extraction method based on matrix solid phase dispersion (MSPD) was developed and validated for the simultaneous cleaning-up and quantitative extraction of illegal dyes (sudan I, sudan II, sudan III and sudan IV) from different sauces and condiments. Several parameters as sorbent, cleaning procedure to eliminate carothenoids and other interferences, and solvents for elution were evaluated to find the optimal MSPD conditions. The best results were obtained using a system containing washed sea sand and Florisil as sorbents and sodium sulphate as desiccant; hexane was used as defatted agent and acetonitrile as elution solvent. Quantitative analyses were performed by liquid chromatography (LC) with diode array detection (DAD). The chromatographic separation was performed on a Phenomenex Synergy Polar RP column with isocratic elution using methanol/acetonitrile/water 65/20/15, v/v/v, as the mobile phase at a flow rate of 1.0mLmin−1 and 30°C of temperature. Under these conditions sudan I–IV recoveries were between 60% and 99% and relative standard deviations ranging from 2.0% to 10.0%. Limits of detection resulted five times lower than the values required by European regulations and were ranged between 0.05 and 0.09μgg−1. The applicability of this MSPD–DAD method to determine illegal sudan dyes in sauce and condiment samples was demonstrated. This method has potential to be applied using a simple instrumentation present in most analytical laboratories.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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