Heavy metals and arsenic fixation into freshwater organic matter under Gammarus pulex L. influence

Organic sediments are a main sink for metal pollutants in aquatic systems. However, factors that make sediments a sink of metals and metalloids are still not clear. Consequently, we investigate the role of invertebrate shredders (Gammarus pulex L.) on quality of metal and arsenic fixation into organic partitions of sediment in the course of litter decay with laboratory microcosm experiments. During the decomposition of leaf litter, G. pulex significantly facilitated the development of small particles of organic matter. The capacity of metal fixation was significantly higher in smaller particles than leaf litter and litter residuals. Thus, G. pulex enhanced metal fixation into the organic partition of sediments by virtue of increasing the amount smaller particles in the aquatic system. Furthermore, invertebrates have a significant effect on formation of dissolved organic matter and remobilization of cobalt, molybdenum and cesium, but no significant effect on remobilization of all other measured elements.     

Reverse phase high performance liquid chromatographic determination of Baygon in water

Abstract

A simple analytical procedure for determination of Baygon in water is described. The Baygon residues are extracted on a C₁₈ SEP‐PAK cartridge and subsequently analyzed by reverse phase high performance liquid chromatography using ultraviolet detection at 272 nm. Water samples spiked with Baygon are found to give greater than 90 percent recoveries.

Concentration levels as low as 20 ppb can be easily detected by this method.     

GC × GC--A New Analytical Tool For Environmental Forensics

Comprehensive two-dimensional gas chromatography, GC 2 GC, is a new analytical tool with a tremendous capability to separate and identify organic compounds in complex environmental samples. GC 2 GC uses two different chromatography columns coupled serially by a modulator to produce a volatility by polarity separation and distribute compound peaks across a two-dimensional retention time plane. The two-dimensional separation produces an order of magnitude more resolved peaks than traditional GC methods. The grouping or ordering of the peaks in the GC 2 GC chromatogram facilitates the identification of unknown compounds and the comparison of complex environmental samples. When a mass spectrometer detector is used, each resolved GC 2 GC peak yields a single-component, interference-free mass spectrum that leads to accurate matching with mass spectral libraries. GC 2 GC examination of marine sediment extracts identified a wide variety of chemical contaminants including polychlorinated biphenyls, p -nonylphenol isomers, polycyclic aromatic hydrocarbons, benzotriazoles, and the alkane, cycloalkane, alkylbenzene, alkylnaphthalene, and biomarker fractions of petroleum. The two-dimensional GC 2 GC chromatogram image permits rapid screening of the sediment extracts for these and other unknown contaminants.     

离子色谱法测定碳酸锶产品中的氯杂质

讨论了在单柱离子色谱仪上用ＴＳＫｇｅｌＩＣ－Ａｎｉｏｎ－ＳＥ柱为分离柱，１ｍｍｏｌ／Ｌ邻苯二到（ＰＨ５．４）作流动相，以电导检测器检测，测定沸水提取碳酸锶产品中的杂质氯的方法。该法简便、快速、准确、无干扰，在测定范围内有良好的线性。最小检出量为０．１μｇ，ＩＣ法与比色法的测定结果基本一致，ＣＩ＾－的含量为０．１６６％，相对标准偏差为２．８％，回收率为９７．９％～１００％。     

Application of chemometric analysis based on physicochemical and chromatographic data for the differentiation origin of plant protection products containing chlorpyrifos

The aim of this study was to investigate the similarities and dissimilarities between the pesticide samples in form of emulsifiable concentrates (EC) formulation containing chlorpyrifos as active ingredient coming from different sources (i.e., shops and wholesales) and also belonging to various series. The results obtained by the Headspace Gas Chromatography–Mass Spectrometry method and also some selected physicochemical properties of examined pesticides including pH, density, stability, active ingredient and water content in pesticides tested were compared using two chemometric methods. Applicability of simple cluster analysis and also principal component analysis of obtained data in differentiation of examined plant protection products coming from different sources was confirmed. It would be advantageous in the routine control of originality and also in the detection of counterfeit pesticides, respectively, among commercially available pesticides containing chlorpyrifos as an active ingredient.     

气相色谱法同时测定制药企业废气中多种挥发性有机物

针对典型制药产品青霉素、阿莫西林、维生素C、对乙酰氨基酚生产过程的挥发性有机物(VOCs)排放特点,建立了吸附-解吸-气相色谱法同时检测制药企业废气中丙酮、乙酸乙酯、异丙醇、苯、甲苯、乙酸丁酯和正丁醇等7种特征VOCs的分析方法。采用活性炭采样管采样-二硫化碳解吸-毛细管色谱柱分离,在解吸时间30 min、柱温35℃保持6 min、30℃/min速率升温到200℃保持2 min的色谱分析条件下,各挥发性有机物可以实现良好的分离;7种物质标准曲线相关系数为0.999 8~0.999 9,相对标准偏差为1.1%~3.2%,检出限为0.004 mg/m3~0.014 mg/m3,7种物质的解吸效率为83.1%~105.1%。结果表明,该方法适用于典型制药企业固定污染源排放废气中特征VOCs的测定。     

离子色谱法测定环境空气中氯化氢降低空白值的方法

用离子色谱法测定环境空气中低浓度氯化氢,是通过测定氯离子质量浓度间接测定氯化氢的质量浓度,测定过程极易受外来氯离子的干扰,使空白值偏高。通过试验确定测定过程中可能存在氯离子干扰的环节,并采取一系列方法消除前期准备、采样和分析全过程中的干扰,以降低空白值。     

碱性消解-伏安极谱法测定土壤中六价铬

分析了汞滴尺寸、支持电介质等因素对碱性消解-伏安极谱法测定土壤中六价铬的影响。在优化实验条件下,该方法检出限为7.65μg/L,相对标准偏差(n=7)为4.6%。以2个样品为例,每个浓度进行6次平行测定,加入六价铬浓度为10μg/L,六价铬的回收率为91.4%~120%,RSD≤5%。与二苯碳酰二肼分光光度法进行比较,2种方法测定值基本一致。     

50 Hz alternating extremely low frequency magnetic fields affect excitability,firing and action potential shape through interaction with ionic channels in snail neurones

In spite of growing concern about the influence of magnetic fields on biological systems, the interaction between extremely low frequency magnetic field (ELF magnetic fields) and biological structures at the cellular level remains obscure. The aim of this study was to investigate if 50 Hz magnetic fields could have an effect on the neuronal excitability and firing responses. Under Current-Clamp condition, exposure to 50 Hz ELF magnetic fields at 2 mT or 0.8 mT intensities resulted in an increase in the peak amplitude of action potential and after hyperpolaization potential in a time dependent manner. Both magnetic field intensities decreased also the firing frequency and the duration of action potential. Taken together, these data suggest that 50 Hz ELF magnetic fields at 2 mT or 0.8 mT intensities may change the electrophysiological behavior of neuronal cells and underlying ion channel currents.     

离子色谱法应用于杭州地表水中有机酸及无机阴离子分布研究

建立了离子色谱-抑制电导法同时检测杭州市地表水中的有机酸及无机阴离子,并对地表水中有机酸及无机阴离子的含量进行探讨.该方法的重现性(RSD)为0.15％ ～4.92％,相关系数r2为0.9990 ～ 0.9999,加标回收率为84.36％～111.05％,最低检出限为0.003～0.028 mg/L.利用该建立的方法,...