Analytical strategies to determine antibiotic residues in fish

The accelerated growth of aquaculture has resulted in a series of harmful effects to human health. The widespread and unrestricted use of antibiotics in this industry, to prevent bacterial infections, leads to remaining amounts in the aquatic environment. This has resulted in the emergence of antibiotic-resistant bacteria in aquaculture environments, in the increase in antibiotic resistance in fish pathogens as well as in the transfer of these resistance determinants to human pathogens. Moreover, the use of large amounts of antibiotics may lead to the presence of residual antibiotics in fish tissue and fish products. Fluoroquinolones, tetracyclines, penicillins, sulphonamides and other antibiotics, exhibiting activity against both Gram-positive and Gram-negative bacteria, are widely used for the treatment and prevention of diseases in fish. An extended and comprehensive review on the recent analytical methodologies concerning antibiotic residues in fish reported in the literature is provided in the present article. Emphasis is given on sample preparation regarding isolation and purification, chromatographic conditions and method validation according to legislation. Results of published assays are comparatively presented and criticised.     

Effect of the displacement reaction on the composition of the magnetic layer in electrodeposited layered nanostructures Co-Cu/Cu and Ni-Cu/Cu

Methods of stripping voltammetry, quartz microgravimetry, and x-ray-fluorescence analysis are employed to explore the copper displacement process on thin electrodeposited layers of pure cobalt and nickel and on deposits of these metals with inclusions of copper. The displacement reaction proceeds at a considerable rate on cobalt in the sulfate and sulfosalicylate solutions and virtually does not proceed on nickel in both the sulfate or sulfate-chloride solutions. An estimate of the rate of the copper displacement reaction following a change in the concentration of copper ions in the solution and in the pH of the sulfosalicylate solution is given. A decrease in the contact exchange rate is facilitated by a decrease in the concentration of copper ions in solution and their participation in the formation of complexes.     

Calibration methods for microdialysis sampling in vivo: muscle and adipose tissue

Calibration methods for microdialysis sampling were studied in the muscle and adipose tissue of rats. Both the delivery method and the no-net-flux method were used to determine the extraction efficiency (EE) of acetaminophen and caffeine in both tissues. There was no concentration dependence of the EE either in vitro or in vivo for either acetaminophen or caffeine. The EEs determined by the delivery and no-net-flux methods were not different. However, the EEs of both caffeine and acetaminophen determined in vitro were significantly higher than those determined in the muscle and adipose. This indicates that mass transfer in the tissue is the rate-determining factor for the EE in vivo. The relative difference between the EE in vitro and the EE in the muscle was smaller than the difference between the EE in vitro and the EE in the adipose. In addition, the EE in the muscle decreased more than the EE in the adipose after the animal was euthanized. This indicated that exchange between the extracellular fluid and plasma is the rate-determining step in mass transport relative to microdialysis sampling. This has a more significant effect on the EE in the muscle than the EE in the adipose. Both the delivery and no-net-flux methods can be used to calibrate microdialysis probes in the muscle and adipose.     

Changes in density and surface tension of water in silica pores

 The density and surface tension of water in small pores of silicas have been investigated. These physical properties of water in the pores were calculated from a comparison of pore volumes and pore radii which were estimated from adsorption and desorption isotherms of nitrogen and water. Below a pore radius of about 5 nm both the density and the surface tension of water in the pores were smaller than those of the bulk liquid and decreased with a decrease in pore size. The density of water in the pores decreased with an increase in the concentration of surface hydroxyl groups. Similarly the surface tension of water in the pores is influenced by the surface hydroxyl groups. Anomalous changes in the density and surface tension of the water in the pores are attributed to the interaction of water molecules with surface hydroxyl groups and hydrogen-bond formation among water molecules. Received: 20 April 1999 Accepted in revised form: 17 November 1999     

An Evidence-Based Review of Application Devices for Nitric Oxide Concentration Determination from Exhaled Air in the Diagnosis of Inflammation and Treatment Monitoring

The measurement of nitric oxide (NO) in exhaled air is used in diagnostics and monitoring the pathologies not only in the respiratory system but also in the oral cavity. It has shown a huge increase in its level in asthma and diseases of the oral cavity. It seems reasonable to undertake research on the impact of inflammation on the level of NO in exhaled air. The aim of the study is to make an evidence-based review of the application of NO levels in exhaled air in the diagnosis of inflammation and treatment monitoring on the basis of selected measuring devices. Methods and Results: This paper presents an example of the application of NO measurement in exhaled air in individual human systems. Selected measuring devices, their non-invasiveness, and their advantages are described. Discussion: The usefulness of this diagnostic method in pathologies of the oral cavity was noted. Conclusions: Measuring the level of NO in exhaled air seems to be a useful diagnostic method.     

青藏高原湖泊影响锂元素迁移和富集的矿物、元素及环境因素——以西藏郭扎错钻孔沉积物为例

作为我国战略性矿产的锂矿,主要赋存于青藏高原盐湖中。湖泊系统中,锂的富集和迁移规律关系到锂矿的高效提取和未来锂矿的储量估算。本文以西藏咸水湖郭扎错的钻孔沉积物为例,结合AMS14C年代和Mg元素含量变化,系统分析了孔隙水、碳酸盐矿物和硅酸盐矿物的锂含量变化,探讨了矿物、镁元素、环境变化和早期成岩作用等对锂元素迁移和富集的影响。郭扎错沉积物中锂和镁大部分存在于硅酸盐矿物中,锂和镁较高的相关性说明二者存在于相同的硅酸盐矿物中,如粘土矿物。大约90%的锂赋存在硅酸盐矿物中,约8.5%的锂赋存在碳酸盐矿物中,孔隙水中的锂含量占比仅约1.5%。碳酸盐矿物中Mg/Li摩尔比值为78–270,是孔隙水中10多倍,而硅酸盐矿物中的Mg/Li摩尔比值稳定在24–29之间。水–沉积物相互作用促进硅酸盐矿物中锂的释放,咸水环境下释放的锂多于淡水环境下。碳酸盐矿物中,锂和镁主要存在于方解石中。镁离子对锂离子的迁移具有阻碍作用,低温、高盐度下的阻碍作用更强。湖泊沉积物可能是湖水锂的一个重要来源。     

Effect of pulp composition on the characteristics of residuals in CMC made from such pulps

Four different spruce sulphite pulp samples were used for the preparation of carboxymethylcellulose (CMC). The characteristics of the unreacted fibre and particle residuals obtained in the CMC-preparation were used to establish a correlation between the hemicellulose in the pulp and the intrinsic viscosity, i.e.,␣cellulose chain length and the occurence of unreacted residuals. It was shown that the residual particles in the CMC consisted of fibres, fibre fractions and gel particles of different degrees of substitution. The results suggested that pulps with long cellulose chains, i.e., pulps with high intrinsic viscosities, resulted in particles that were more substituted and more swollen. These pulps also resulted in more substituted hemicelluloses in the CMC and more substituted residuals. It was also suggested that galactoglucomannan in the cellulose pulps is favourable for the swelling which results in more substituted hemicelluloses in the CMC and more swollen residuals. The amount of residuals was influenced mainly by the characteristics of the cellulose in the pulp. It is therefore believed that a combination of high viscosity and a suitable combination of hemicelluloses is the most favourable way of eliminating the occurrence of undissolved residuals in CMC.     

Electrophoretic studies for determining soy proteins–xanthan gum interactions in foams

The aim of this work was to elucidate soy proteins–xanthan gum interactions at a molecular level by studying protein composition at the air–water interface of foams and in the solutions used to make them and to see if the different properties of heat denatured protein were reflected in the proportions in which they were present at the interface or in the ability to interact with xanthan. To this end SDS-PAGE and densitometry was employed. Initial protein concentration and xanthan influenced the composition of proteins in the solutions used to make the foams. The increase in NSP concentration of solutions (0.5–6 wt.%) in the absence of xanthan promoted the formation of aggregates of low molecular weight (160 kDa), the association of A an B polypeptides and a decrease in and ′ subunits. As DSP concentration of solutions increased, an increase in the proportion of aggregates of high molecular weight (above 200 kDa) and B-polypeptide was observed. On addition of xanthan (0.025 and 0.05%) to protein solutions (0.5 and 2%), the formation of aggregates of high molecular weight was favoured for both NSP and DSP. In the absence of xanthan, no preferential adsorption of soy polypeptides was observed at the air–water interface of NSP foams. However in DSP foams, there was a preferential adsorption of B-polypeptides. Xanthan present in NSP foams (0.5 or 2%), caused an increase in the proportion of aggregates of high molecular weight at the interface as compared with the composition of solutions used to make the foams. An increase in proportion of AB-polypeptides (for 0.5% NSP and 0.025% xanthan) and B-polypeptides together with polypeptides of molecular weight lower than 14 kDa (for 0.5% NSP and 0.05% xanthan) was also observed at the interface in NSP foams. On the contrary, the presence of xanthan in DSP foams caused a decrease in the proportion of aggregates of high molecular weight and a concomitant increase in B-polypeptide. The B-11S polypeptide predominated the interface of DSP foams probably for its hydrophobicity and basic characteristics.     

Evaluation of the Fate of Aldicarb and Its Metabolites in Oranges

Abstract

The accumulation, persistence and fate of systemic pesticide aldicarb was melencholy evaluated in orange crops. The concentration of this pesticide and its two toxic metabolites, aldicarb sulfoxide and aldicarb sulfone was determined in leaves, rind and pulp of three orange varieties (Satsuma, Navelina and Clemetina de Nules) and in the top soil of the orange groves. The groves were located in two different places in the Valencia Community (Spain). The analysis showed that the aldicarb concentration was lower than those of aldicarb sulfoxide and aldicarb sulfone. In all cases, the residues persisted at least 160 days in vegetable samples and between 157 and 227 days in soil samples. Residue concentrations measured in the soil samples were highly variable but a relation with the organic matter content can be observed. The residue levels found in vegetal products were higher in leaves than in rind, and in rind than in pulp. The maximum residue values were obtained between 47 and 70 days after the application. One hundred days after treatment (Security period) the residue levels of total fruit were lower than the maximum residue level of 0.2 mg/kg established by law.     

Butyltin compounds in severn sound,lake huron,canada

Severn Sound is a heavily used recreational and beating area in the southeast corner of Georgian Bay, Lake Huron, Canada. Because of the concern over the possible release of tributyltin species (TBT) from antifouling paints on boat hulls and marinas, surveys were carried out in 1989 and 1992 to determine the presence of this species and its degradation products dibutyltin (DBT) and monobutyltin (MBT) in this area. Many fish (pike and young–of–the–year spottail shiners) and sediment samples collected in 1989 contained detectable levels of TBT. A maximum concentration of TBT was recorded in northern pike in the spring to be 240 ng Sn g^?1. Maximum levels occurred in marinas during the beginning of the boating season and significantly reduced during the summer and early autumn, although the maximum value of TBT in sediment (392 ng Sn g^?1) was observed in the summer of 1989. The seasonal variation of TBT levels was further substantiated in the subsequent 1992 study, in which sediments from three areas in a marina were sampled at monthly intervals from May to October. TBT levels were much higher in May and then generally decreased with time. Mussels (Elliptio complanta) caged in the marina for three months also contained TBT. DBT was frequently detected in the sediments but less frequently in fish and mussels. MBT was generally below detection limits. Plants (macrophytes and cladophora) contained very small amounts of butyltin compounds.     

GC-MS analysis of penta- and tetra-cyclic triterpenes from resins of Pistacia species. Part II. Pistacia terebinthus var. Chia

Pistacia species contain oleoresins with bioactive triterpenes. In this study triterpenes, including minor components, were identified and quantified in both neutral and acidic fractions of Pistacia terebinthus var. Chia resin, grown exclusively in Chios island (Greece), collected traditionally, as well as using stimulating agents (liquid collection). It was proved that these two resin samples were composed of several different minor triterpenes, while major constituents were similar but in different proportions. Compounds that differentiated two resin samples of P. lentiscus and P. terebinthus var. Chia, both traditionally collected, were detected, in order to identify the nature of resins present in archaeological materials. In the traditionally collected resin, 37 triterpenes were identified, 12 in the acidic and 25 in the neutral fraction. In the liquid collection resin 10 compounds were identified in the acidic and 23 in the neutral fraction, while 16 compounds were not contained in the traditionally collected resin. The main triterpenes in both resin samples collected traditionally and using stimulating agents were: isomasticadienonic acid (23.6 and 26.3% w[sol ]w of the triterpenic fraction, respectively), 28-norolean-17-en-3-one (16.3 and 17.5% w[sol ]w of the triterpenic fraction, respectively) and masticadienonic acid (5.8 and 6.0% w[sol ]w of the triterpenic fraction). In this study the qualitative and quantitative composition of triterpenes was compared in the Pistacia lentiscus and P. terebinthus var. Chia resin samples collected with the traditional and new liquid techniques, and also triterpenes in resins of P. terebinthus obtained by the traditional technique and using stimulating agents. The aim of the study was also to examine whether the collection technique influenced the triterpenes contained in P. terebinthus var. Chia resin samples.     

Matrix-assisted laser desorption/ionization mass spectrometry for the characterization of ionic liquids and the analysis of amino acids, peptides and proteins in ionic liquids

Ionic liquids are interesting solvents for a number of applications in chemistry and biotechnology. We characterized five different ionic liquids by laser desorption/ionization (LDI) and by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) and studied the analysis of amino acids, peptides and proteins dissolved in these solvents. Signals of both anions and cations of the ionic liquids could be observed both in LDI- and in MALDI-MS. In the latter case, adduct formation between anions and cations of the analytes was observed. Amino acids, peptides and proteins could be analyzed in ionic liquids after addition of matrix substances. Sodium and potassium adducts were not observed in any analysis involving ionic liquids. Low molecular mass compounds and peptides could be analyzed best in the presence of water-immiscible ionic liquids, whereas proteins gave the best results in water-miscible ionic liquids. Optimal analysis conditions such as molar matrix-to-analyte and ionic liquid-to-matrix ratios were determined. Homogeneity of samples in the presence of ionic liquids was reduced compared with classical MALDI preparations. Relative quantitation of amino acids was possible using isotope-labeled internal standards. MALDI-MS thus can be used for the analysis of chemical reactions and the screening of enzyme-catalyzed reactions in ionic liquids and for the analysis of the biocatalysts dissolved in these solvents. Theoretical aspects of ion formation in the presence of ionic liquids both in LDI and MALDI analysis are discussed.     

本体与界面条件下MAPTMS水解-缩合过程中簇集行为比较研究

以甲基丙烯酰氧丙基三甲氧基硅烷(MAPTMS)为前驱体,利用荧光光谱、在线衰减全反射红外光谱(In-situ ATR-FT-IR),比较性地研究了在本体及气液界面条件下MAPTMS在酸性介质中的水解-缩合过程.借助于LB膜技术,测定了MAPTMS在气液界面水解-缩合反应过程中的π-A曲线.不论在本体相还是气液界面相,荧光探针芘均表现出明显的芘分子完全重叠及部分重叠的激基缔合物的荧光发射特征.结果表明:MAPTMS水解产物在水相中发生簇集,而且簇集体疏水端相互作用存在一定刚性.芘的荧光光谱随反应进行表现出显著变化,但本体相荧光光谱变化较气液界面相剧烈.ATR-FT-IR光谱在线检测表明:本体水解缩合产物具有较高的聚合度,而气液界面水解缩合产物聚合度较低.上述结果说明体系中存在簇集行为的显著变化,且在气液界面MAPTMS水解产物受限程度比本体相大.分子在气液界面上的聚集行为也由-πA曲线的结果得到进一步证实.文中依据MAPTMS水解产物具有类似表面活性剂的特性对上述实验结果给予了解释.     

Antioxidative effects of flavonols and their glycosides against the free-radical-induced peroxidation of linoleic acid in solution and in micelles

The antioxidative effect of flavonols and their glycosides against the peroxidation of linoleic acid has been studied in homogeneous solution (tBuOH/H(2)O, 3:2) and in sodium dodecyl sulfate and cetyl trimethylammonium bromide micelles. The peroxidation was initiated thermally by the water-soluble initiator 2,2'-azobis(2-methylpropionamidine) dihydrochloride, and the reaction kinetics were studied by monitoring the formation of linoleic acid hydroperoxides. The synergistic antioxidant effect of the flavonols with alpha-tocopherol (vitamin E) was also studied by following the decay kinetics of alpha-tocopherol and the alpha-tocopheroxyl radical. Kinetic analysis of the antioxidative process demonstrates that the flavonols are effective antioxidants in solution and in micelles, either alone or in combination with alpha-tocopherol. The antioxidative action involves trapping the initiating radicals in solution or in the bulk-water phase of the micelles, trapping the propagating lipid peroxyl radicals on the surface of the micelles, and regenerating alpha-tocopherol by reducing the alpha-tocopheroxyl radical. It was found that the antioxidant activity of the flavonols and their glycosides depends significantly on the position and number of the hydroxy groups, the oxidation potential of the molecule, and the reaction medium. The flavonols bearing ortho-dihydroxy groups possess significantly higher antioxidative activity than those without such functionalities, and the glycosides are less active than their parent aglycones. The activity of the flavonols is higher in micelles than in solution, while the activity of alpha-tocopherol is lower in micelles than in solution. This is because the predominant factor for controlling the activity is the hydrogen-bonding interaction of the antioxidant with the micellar surface in the case of hydrophilic flavonols, while it is the inter- and intramicellar diffusion in the case of lipophilic alpha-tocopherol.     

沱江流域Pb、Cd的环境污染化学行为研究

对沱江流域金堂、简阳、内江三地河流沉积物中重金属Pb和Cd含量及其时空分布特征进行了研究,并结合与沉积物中Fe、Mn和LOI等参数的相关性对河流沉积物中Pb和Cd地球化学性质进行了初步的分析和讨论。结果表明,沱江三地沉积物中Cd、Pb含量不高,平均含量按上、中、下游次序逐渐降低;从垂向分布行为看,Cd在上游金堂地区上部含量高于下部,而中、下游两地则相反,而Pb均随着深度的增加而减少,反映了近年来人类活动所产生Pb污染的加剧;TOC、沉积物性状和上覆水体中的物化性质对于其垂向分布有着较大影响。对于深入揭示水环境中重金属的环境地球化学循环有着重要的指导意义。     

Fate and occurrence of X-ray contrast media in the environment

Interest in the presence of pharmaceuticals in the environment has recently increased. Despite continuous research efforts there is still a large gap in our knowledge of their fate and effects on the ecosystem. This review covers current information on the occurrence of iodinated X-ray contrast media (ICM) in the environment and developments in the analysis of these highly polar organic micropollutants in aqueous environmental samples. Findings from monitoring surveys conducted on wastewater-treatment plants (WWTP), surface waters, and drinking waters are compiled, and strategies for removal of the compounds in WWTP and waterworks using advanced treatment are reported. Characteristics and advantages of different compound-specific or element-specific mass spectrometric techniques used to monitor ICM in the environment are compared, and applications in elucidation of the structures of biotransformation products, generated in laboratory-scale experiments that simulate sewage treatment or river water/sediment systems, are described.     

煤中Se、Cd在焦化过程中迁移规律的研究

利用现代分析测定仪器和实验室模拟手段,以煤及固相(焦炭)、液相焦化产物(焦油、氨水)、气相焦化产物(煤气)中有害微量元素镉(Cd)、硒(Se)为研究对象。通过测定,比较不同煤化度煤种微量元素的含量,并归纳探讨了配合煤中Cd、Se元素在焦化过程中的迁移规律。发现煤化度不同的煤中,镉元素随着煤变质程度升高而减少;硒元素含量对比:QFFM,JM和SM中含量相差不大。在模拟焦化温度1 000℃环境下,分别有45%的硒和48%的镉元素转移到焦炭中,2%的硒和7%的镉转移到氨水中,12%的硒和15%的镉转移到焦油中,并通过物料衡算,发现有41%的硒和30%的镉释放到煤气中。     

Pesticide residues in groundwaters and soils of agricultural areas in the Águeda River Basin from Spain and Portugal

This research has evaluated the agricultural impact of the use of pesticides in small agricultural areas in the Águeda river basin, which straddles the Spanish-Portuguese border. Sixteen pesticides frequently used in the area, including herbicides, fungicides and insecticides and some of their degradation products, were monitored in 52 groundwater samples and 42 soil samples taken around them, using a developed multi-residual analytical method based on SPE-LC-MS. Sampling was carried out in two different seasons (winter and summer). The results indicated the presence of pesticides at several levels, both in groundwaters and soils. Thirteen of the pesticides studied were detected in one or more of the groundwater samples analysed, but only three pesticides were detected in the soil samples. Terbuthylazine, cyprodinil, tebuconazole and chlorpyrifos were the pesticides most frequently detected in groundwaters, whereas terbuthylazine, metalaxyl and tebuconazole were the sole compounds detected in soils. The distribution of the concentrations in groundwaters indicated that up to 80% and 70% of the samples collected in the summer on the Spanish and Portuguese sides, respectively, exceed the quality standards of 0.1 µg L^?1 for one or more individual compounds and, in turn, up to 64% and 40% exceed the quality standards of 0.5 µg L^?1 for all compounds. The presence of pesticide residues in the groundwaters and soils analysed may well be explained by the use of these compounds in agricultural practices.     

Therapeutic use of hyaluronan

Hyaluronan used today as a therapeutic agent in human and animal medicine must be in a highly purified form, free of immunologically active protein molecules, from endotoxin and from inflammatory molecules originating from the tissues or bacterial cultures—the source of hyaluronan. All hyaluronans, whether in liquid or in covalently crosslinked gel form, must have certain elastoviscous properties to be usable for current therapeutic applications. Elastoviscous properties are especially important in the ophthalmic viscosurgical use. The metabolism of hyaluronan is very fast in most tissues, except in the vitreus. The ability of injected hyaluronan with a short half-life time in the joint to accomplish long-lasting analgesia represents a challenge for the design of the various products. The history of the therapeutic use of hyaluronan and its present status is described, with emphasis on its use in ophthalmic surgery and for a long-lasting analgesia in arthritic joints in humans and animals. The use of hyaluronan gels is described in viscoaugmentation as injected into the dermal layer of the skin. Hyaluronan gels were also used as viscosupplements injected into sphincter muscles to improve their function in aging or disease. The use of hyaluronan and its gel for drug delivery was suggested several decades ago, and is also mentioned.