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Like many other organic ligands, amine-based complexing agents in analytical chemistry have demonstrated substantial improvements in sensitivity and selectivity in determining metals by flame-atomic absorption spectrometry (FAAS) and electrothermal atomisation atomic absorption spectrometry (ETAAS). Amines represent a particular case for diverse potential complexing agents owing to the lone pair electrons in the nitrogen atom being capable of forming dative covalent bonds. Amines can analytically generate useful pH-dependent green switchable solvents. In this context, this work aims to critically review the diverse uses of amines in the FAAS/ETAAS fields in a comprehensive manner by mainly focusing on their effects on the atomisation processes, their behaviour as complexing agents and their possible direct and indirect determination by the AAS techniques. Various theoretical topics related to the solvent extraction processes involving amines also enhance the usefulness of this kind of compound for the AAS techniques. Further, extrapolating their usefulness in combination with other analytical techniques is straightforward. [ABSTRACT FROM AUTHOR]

Listeria spp. is an important foodborne bacterium. This microorganism can be discarded from milk using high temperatures such as pasteurization. The milk-processing methods of many small-scale retailers lack quality control. This study was to survey Listeria contamination at the farm and retailer levels. The retailers were to be interviewed for knowledge, attitude, and practice as well. Finally, we were to determine the heating processes employed to decontaminate microorganisms by the retailers using a reference strain of L. monocytogenes. Milk samples were collected from milk-collecting centers and small-scale retailers. In clinical trial, the processing measures were proved for the proficiency in L. monocytogenes decontamination. One out of 99 farms presented Listeria contamination, confirmed to L. marthii. Fifty small-scale retailers participated in the second part, including 13 males and 37 females. No Listeria spp. but Staphylococcus spp. and Bacillus spp. were identified in the processed milk. Data analyses revealed that the location of the retailer was significantly associated with the volume they routinely ordered per lot and the milk-processing time the retailers used to treat milk. Knowledge on raw milk contamination is significantly associated with the stocking or processing of the whole milk lot. Processing measures presale were significantly influenced by the gender of the retailer. The male retailer reportedly spent less time treating milk compared to their female counterparts. To assess the efficacy of the processing methods, a trial using L. monocytogenes as a reference strain was conducted. Interestingly, no L. monocytogenes was detected after sample treatment, but other microorganisms such as S. epidermidis, S. warneri, and Escherichia coli were found, suggesting potential issues with cross-contamination. In conclusion, while the trial implied that the retailers' processes were effective in L. monocytogenes decontamination, the study highlighted inappropriate practices and the risk of cross-contamination. Continuous monitoring of product safety in small-scale milk retailers is imperative to ensure consumer well-being. [ABSTRACT FROM AUTHOR]

For dairy processors, spoilage and pathogenic spore‐forming bacteria are key sources of concern, not only due to their ability to remain dormant in a desiccated state in powders and to survive heat treatments, but also their ability to form biofilms in the vegetative state that lead to contamination of foods. These include members of the genera Bacillus, Geobacillus, Anoxybacillus, Brevibacillus, Paenibacillus and Clostridium, many of which are associated with food poisoning and spoilage. Here, we review the common bacterial species that form spores in whey powders and their sources and provide insights into their risks and strategies to control them. [ABSTRACT FROM AUTHOR]

Scattering interference (SI) is the possible scattering of intense radiation from the source, which is superimposed directly onto the resonance fluorescence signal of interest. It will lead to sham high results when using a non-dispersive optical system for As detection. To solve the SI of As, in this paper, a real-time suppression method named the non-fluorescent line ratios (NFLR) method was proposed after detailed analysis using dispersive atomic fluorescence spectrometry based on an ultraviolet digital micromirror device spectrometer (UV-DMD-AFS). Specifically, according to the characteristic of fast wavelength selection of UV-DMD-AFS, the source of SI and the effect of external factors on SI were analyzed, the non-fluorescent lines of As and the ratios of non-fluorescent lines to fluorescent lines (simplified as "Ratios") were determined, and the stability of the Ratios was studied under different parameters. The NFLR method suppressed the SI of As effectively, whose suppression proportion was 98.50–102.43%. Compared with the non-dispersive AFS, the NFLR method had a higher long-term accuracy (>99.20%) validated with certified reference materials (CRMs) of water quality samples. [ABSTRACT FROM AUTHOR]

Orf is a zoonotic and highly contagious disease caused by Orf virus (ORFV) infection. Orf outbreaks in sheep and goats usually lead to high culling rate and mortality in newborn kids and lambs, posing a great threat to the development of goat and sheep industry. Human Orf occurs via direct contact with infected animals or fomites. While this disease is traditionally thought to spread through direct contact, whether other transmission routes exist remains unclear. Herein, we report the detection of ORFV in the saliva and milk of dairy goats without clinical Orf symptoms. Further analyses showed that these ORFV are infectious, as they can induce characteristic cytopathic changes in primary mammary and lip cells. Importantly, these ORFV can induce typical Orf lesions after inoculation in ORFV-free dairy goats. This is the first study showing that live, infectious ORFV can be isolated from the saliva and milk of asymptomatic goats, highlighting novel potential transmission routes of ORFV. These findings provide a novel idea for the prevention and control of Orf spread. [ABSTRACT FROM AUTHOR]

A dispersive atomic fluorescence spectrometer based on a UV digital micromirror device (UV-DMD-AFS) has been proposed by our team for attenuating spectral and scattering interferences. Software is nontrivial for the automation of component control and sample analysis in the new instrument. In this work, the software was developed using the C# programming language together with multi-threading and combined with the SQLite database, which consists of component control and data acquisition, database, wavelength initialization, and real-time interference reduction module. To realize the accurate analysis of the trace heavy metal concentration, the spectral interference was avoided by measuring the non-interference wavelength, and the scattering interference was eliminated by the real-time proportional coefficient method. The microsecond rotation speed of the DMD is the key to achieving real-time reduction. The concentration of arsenic in Water Quality (GSB 07-3171-2014) was detected to validate the practicability of the software with the concentration deviation of 0.02 ng/mL. [ABSTRACT FROM AUTHOR]

Consumers appreciate leafy green vegetables such as baby leaves for their convenience and wholesomeness and for adding a variety of tastes and colors to their plate. In Western cuisine, leafy green vegetables are usually eaten fresh and raw, with no step in the long chain from seed to consumption where potentially harmful microorganisms could be completely eliminated, e.g., through heating. A concerning trend in recent years is disease outbreaks caused by various leafy vegetable crops and one of the most important foodborne pathogens in this context is Shiga toxin-producing Escherichia coli (STEC). Other pathogens such as Salmonella, Shigella, Yersinia enterocolitica and Listeria monocytogenes should also be considered in disease risk analysis, as they have been implicated in outbreaks associated with leafy greens. These pathogens may enter the horticultural value network during primary production in field or greenhouse via irrigation, at harvest, during processing and distribution or in the home kitchen/restaurant. The hurdle approach involves combining several mitigating approaches, each of which is insufficient on its own, to control or even eliminate pathogens in food products. Since the food chain system for leafy green vegetables contains no absolute kill step for pathogens, use of hurdles at critical points could enable control of pathogens that pose a human health risk. Hurdles should be combined so as to decrease the risk due to pathogenic microbes and also to improve microbial stability, shelf-life, nutritional properties and sensory quality of leafy vegetables. The hurdle toolbox includes different options, such as physical, physiochemical and microbial hurdles. The goal for leafy green vegetables is multi-target preservation through intelligently applied hurdles. This review describes hurdles that could be used for leafy green vegetables and their biological basis, and identifies prospective hurdles that need attention in future research. [ABSTRACT FROM AUTHOR]

The second part of this compendium concludes with a collection of phase change enthalpies of organic molecules inclusive of C11-C192 reported over the period 1880-2015. Also included are phase change enthalpies including fusion, vaporization, and sublimation enthalpies for organometallic, ionic liquids, and a few inorganic compounds. Paper I of this compendium, published separately, includes organic compounds from C1 to C10 and describes a group additivity method for evaluating solid, liquid, and gas phase heat capacities as well as temperature adjustments of phase changes. Paper II of this compendium also includes an updated version of a group additivity method for evaluating total phase change entropies which together with the fusion temperature can be useful in estimating total phase change enthalpies. Other uses include application in identifying potential substances that either form liquid or plastic crystals or exhibit additional phase changes such as undetected solid-solid transitions or behave anisotropically in the liquid state. [ABSTRACT FROM AUTHOR]

Amberlite XAD-4 modified withN-para-anisidine-3,5-di-tert-butylsalicylaldimine was investigated as a new chealting sorbent for the selective separation and preconcentration of Cu(II). The metal ion was retained by chemical sorption on the modified resin, eluted by hydrochloric acid, and determined by high-resolution continuum source flame atomic absorption spectrometry. The prepared resin was characterized for the solid-phase extraction of Cd2+, Co2+, Cr3+, Cu2+, Fe3+, Mn2+, Ni2+, Pb2+, and Zn2+in a column. The influence of the pH, the mass of solid phase, eluent, flow rate, and sample volume was optimized. Using the optimum conditions, only Cu(II) showed quantitative sorption at the 95% confidence level, and the recoveries of the other metal ions were below 80%. A preconcentration factor 125 was obtained for Cu(II) with a limit of detection of 0.56 µg L−1. The method was used for the determination of Cu(II) in tap water, river water, tomato leaves, and fish. The relative standard deviation and the relative error were lower than 7%. [ABSTRACT FROM PUBLISHER]

Double isotope dilution inductively-coupled plasma mass spectrometry ( ID ICP/ MS) is widely used for the certification of trace elements in candidate reference materials by many national metrology institutes because it allows accurate and reliable determination of the elemental content in complex matrices of food samples. The presence of isobaric interferences, however, may cause nonnegligible biases in isotope ratio measurements, giving erroneous analytical results. In this study, a matrix separation was carried out using anion exchange chromatography to eliminate isobaric interferences so that an accurate determination of Cd in candidate reference materials could be obtained. Synthetic blends of Cd and interfering elements were used to optimize the matrix separation conditions. The isobaric interferences for cadmium isotopes in various food samples were investigated using the optimized method. Without matrix separation, a significant bias, up to 18%, was observed in a soybean sample. It was about 3% in an herb sample. With the proper selection of isotopes and elimination of isobaric interferences, Cd concentrations in food candidate reference materials were robustly certified. [ABSTRACT FROM AUTHOR]

Urea-formaldehyde resins are bulk products of the chemical industry. Their synthesis involves a complex reaction network. The present work contributes to its elucidation by presenting results from detailed NMR spectroscopic studies with different methods. Besides1H NMR and13C NMR,15N NMR spectroscopy is also applied.15N-enriched urea was used for the investigations. A detailed NMR signal assignment and a model of the reaction network of the hydroxymethylation step of the synthesis are presented. Because of its higher spectral dispersion and the fact that all key reactions directly involve the nitrogen centers,15N NMR provides a much larger amount of detail than do1H and13C NMR spectroscopy. Symmetric and asymmetric dimethylol urea can be clearly distinguished and separated from monomethylol urea, trimethylol urea, and methylene-bridged urea. The existence of hemiformals of methylol urea is confirmed. 1,3,5-Oxadiazinan-4-on (uron) and its derivatives were not found in the reaction mixtures investigated here but were prepared via alternative routes. The molar ratios of formaldehyde to urea were 1, 2, and 4, the pH values 7.5 and 8.5, and the reaction temperature 60 °C. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A method for the determination of nickel in water was developed. The procedure involves preconcentration of nickel by using dispersive liquid-liquid microextraction. The Ni(II) ions were extracted in chloroform in the form of complex with the reagent 2-(2′-benzothiazolylazo)- p-cresol. Ethanol was used as the disperser solvent. After injection of the extracting mixture in a solution of nickel, a cloudy mixture was observed. A quick centrifugation induces phase separation and thus the settling of rich phase. The nickel content in the rich phase is measured by flame atomic absorption spectrometry. Under optimal conditions, the limit of detection and quantification obtained were 1.4 and 4.7 µg L−1, respectively. Some parameters used to characterize preconcentration systems, such as enrichment factor and consumption index were calculated and resulted in 29 and 0.34 mL, respectively. After optimization of variables and determination of analytical characteristics, the method was used for the analysis of certified reference materials (BCR-713: wastewater, effluent and BCR-414: plankton) and real water samples. [ABSTRACT FROM AUTHOR]