固相萃取法分析水生生物体中17种酞酸酯类环境激素

水生生物样品去壳、搅碎、匀浆;干货样品则首先烘干、研磨和过筛。以丙酮作为提取剂超声波辅助提取3次,提取液经无水硫酸钠脱水后进行氮吹浓缩;浓缩液经处理过的Florisil硅藻土吸附柱净化和乙酸乙酯/己烷(1/5,V/V)洗脱剂洗脱与浓缩后,采用气相色谱-电子轰击电离源/质谱法进行定性分析与内标法定量分析。实验优化与选择了提取剂的种类、吸附剂的种类及其活化条件、洗脱剂的种类等样品前处理过程,并讨论了分析空白值的控制问题。分析方法的线性相关系数均大于0.99987,方法检出限均小于3.67μg/L,平均加标回收率为64.1%~124%,方法的相对标准偏差均小于16.4%。此分析方法成功地应用于3种鱼类(刀鱼、黑鱼、草鱼)、2种贝类(沙螺、牡蛎)、1种甲壳类(明虾)、1种头足类(章鱼)、2种植物(海带、海藻)和2种干货(干海带、丁香鱼干)样品中17种酞酸酯类环境激素含量的同时分析,所分析的样品都检测到邻苯二甲酸二甲酯、邻苯二甲酸二异丁基酯和邻苯二甲酸二丁酯,在大部分样品中还检测出邻苯二甲酸二乙酯和邻苯二甲酸二乙基己基酯,说明此5种酞酸酯已造成了一定程度的水体污染。     

免疫亲和柱净化-液相色谱-串联质谱法测定海洋生物中河豚毒素

建立了海洋生物中河豚毒素的免疫亲和柱净化-液相色谱-串联质谱分析方法。采用1%乙酸-甲醇提取样品,提取液通过磷酸盐缓冲液稀释,调节至pH 7~8,经免疫亲和柱富集和净化后,LC-MS/MS测定,外标法定量。在ACQUITY UPLC BEH Amide亲水柱上进行分离,流动相为乙腈和含有0.1%甲酸的5 mmol/L乙酸铵溶液,梯度洗脱,电喷雾正离子多反应模式监测。河豚毒素在0.3~20.0μg/L线性范围内,相关系数大于0.997,定量限为0.3μg/kg,回收率为88.7%~102.3%,相对标准偏差2.0%~6.4%。本方法重现性好、灵敏度高,适用于海洋生物中河豚毒素的测定。     

常压湿式消解/常压微波消解-原子光谱法测定近海海洋生物体中Cu、Pb、Cd与Hg、As

采用常压湿式消解、常压微波消解两种方法处理近海海洋生物体,以石墨炉原子吸收法测定Cu、Pb、Cd和氢化物发生原子荧光法同时测定Hg、As。实验表明,以常压湿式消解法处理生物体,其Cu、Pb、Cd回收率分别为92%、103%、105%,而Hg、As的回收率分别是52%、58%。以常压微波消解法处理生物体,其Cu、Cd、Hg、As回收率分别为86%、94%、112%、94%,但用于Pb的测定,其回收率严重偏低。常压湿式消解、常压微波消解分别被用于海洋生物体样品中Cu、Pb、Cd和Hg、As的测定,有较好的测定结果。     

The role of nickel(II) on the homochirality of amino acids in living systems

<正>The origin of homochirality in living organisms is controversial,stands out of being particularly important and a question which is still not satisfactorily answered.A mental picture of sequence of events that is thought to have preceded the existence of chirality in molecules is described.A chemical model to mimic the original abiotic conditions in an attempt to explain the preference of homochirality in living systems was tried.The effect which might have influenced this preference is presented.The surprising and unexpected results are indeed interesting,significant,repeatable and indicate that complexing alanine with nickel(Ⅱ) ion alters the racemization rates of D and L isomers of the amino acid.However,why this difference happens is unclear and is difficult to explain.     

Reversed-phase high-performance liquid chromatography–electrospray mass spectrometry profiling of transgenic and non-transgenic maize for cultivar characterization

A reversed-phase high-performance liquid chromatography–electrospray mass spectrometry (RP-HPLC–ESI-MS (ion trap)) method is developed, for the first time, for profiling transgenic and non-transgenic maize with the aim of cultivar characterization. To optimize chromatographic conditions the following parameters were studied: column, gradient, and ion-pairing reagent. Moreover, the influence in the MS signal of the variation of the capillary voltage and the accumulated ions in the trap was also studied. The developed method was applied to the profiling of different protein fractions (albumin, globulin, prolamin, and glutelin) isolated from Bt transgenic and non-transgenic maize cultivars. Moreover, different maize samples, namely, maize cultivars from different geographical origins (USA, Canada, France, and Spain), transgenic maize samples with certified GMO content, and three transgenic Bt maize cultivars with their isogenic non-transgenic counterparts (Aristis Bt vs. Aristis, PR33P67 vs. PR33P66, and DKC6575 vs. Tietar) were profiled by the developed method. Mass spectra obtained for certain peaks in the maize cultivars studied resulted, in some occasions, useful for cultivar characterization and differentiation. The comparison of UV and MS profiles and mass spectra corresponding to the protein fractions with those of the whole seeds enabled the assignment of some peaks.     

Profile and relative concentrations of fatty acids in corn and soybean seeds from transgenic and isogenic crops

In this work 44 fatty acids, which were analyzed as methyl esters by GC/MS in scan mode, have been determined in genetically modified corn and soybean seeds. Their relative concentrations have been compared with those of isogenic lines grown in the same conditions. Studied compounds comprised saturated and unsaturated fatty acids, including cis/trans isomers and minor fatty acids. A classical soxhlet extraction and an accelerated solvent extraction have been assayed to extract the fatty compounds from seeds and the GC separation has been carried out on a biscyanopropylpolysiloxane chromatographic column. Soxhlet extraction was selected as the most convenient and applied to compare the samples. Specific compounds, which could denote the origin of the crop have not been observed, but for some sample pairs, significant differences have been found in relation to the percentage of certain acids; the highest differences for major acids were 4.1% in corn and 4.8% in soybean. The concentrations of long chain acids such as 24:0, 26:0 and 28:0 were higher in some isogenic lines whereas the concentrations of short chain acids such as 6:0, 8:0, 9:0, 10:0 and 12:0 were higher in their transgenic counterparts.     

Fast and sensitive detection of genetically modified yeasts in wine

In this work, a novel screening methodology based on the combined use of multiplex polymerase chain reaction (PCR) and capillary gel electrophoresis with laser induced fluorescence (CGE-LIF) is developed for the fast and sensitive detection of genetically modified yeasts in wine. As model, a recombinant EKD-13 Saccaromyces cerevisiae strain was selected and different wines were prepared using either recombinant or conventional yeasts. Special emphasis is put on the yeast DNA extraction step, exploring different commercial and non-commercial methods, in order to overcome the important difficulty of obtaining amplifiable DNA from wine samples. To unequivocally detect the transgenic yeast, two specific segments of the transgenic construction were amplified. In addition, a third primer pair was used as amplification control to confirm the quality of the yeast DNA obtained from the extraction step. CGE-LIF provides high sensitivity, good analysis speed and impressive resolution of DNA fragments, making this technique very convenient to optimize multiplex PCR parameters and to analyze the amplified DNA fragments. Thus, the CGE-LIF method provided %RSD values for DNA migration times lower than 0.82% (n=10) with the same capillary and lower than 1.92% (n=15) with three different capillaries, allowing the adequate size determination of the PCR products with an error lower than 4% compared to the theoretically expected. The whole method developed in this work requires less than one working day and grants the sensitive detection of transgenic yeasts in wine samples.     

A Comparison of Fluorescent Pigments From Flavobacterium and Sphingobacterium Species

Abstract

An extraction procedure was developed for the isolation of fluorescent pigments from species of Flavobacterium and Sphingobacterium. This procedure was conducted at room temperature. Thereby the possibility of thermal degradation of the fluorescent pigments present in these organisms was reduced compared to previously reported extraction methods in which pigments were extracted after heating with strong base. Extracts from strains of eight species of these two genera have been evaluated using a video fluorometer (VF). This instrument rapidly provides a two-dimensional fluorescence spectrum of each extract. Data from replicate extracts of the organisms have been compared in order to evaluate the potential for identification of these microorganisms on the basis of their fluorescent pigment content. Similarities between the fluorescence spectra of two of the Flavobacterium species and Sphingobacterium mizutae support earlier studies which have shown that these organisms are related on the basis of their content of menaquinones and cellular fatty acids.     

Organotin compounds in agriculture since 1980. Part 2. Acaricidal,antifeedant, chemosterilant and insecticidal properties

The object of this review paper is to provide a guide to agrochemical research involving organotin compounds which has been performed since 1980. The information is presented in a tabular form and is divided into four main sections as indicated by the title. Each section is then subdivided to cover the various commercial organotin compounds. A final subsection lists investigations involving novel compounds. An additional section covers the effects of organotin agrochemicals on non-target organisms. A table of the contents has been provided to enable ease of reference. Acaricidal, antifeedant, chemosterilant and insecticidal properties are covered here. Fungicidal, bactericidal and herbicidal aspects are covered in Part 1.     

Biomineralization of unicellular organisms: an unusual membrane biochemistry for the production of inorganic nano- and microstructures

With evolution, Nature has ingeniously succeeded in giving rise to an impressive variety of inorganic structures. Every organism that synthesizes biogenic minerals does so in a form that is unique to that species. This biomineralization is apparently biologically controlled. It is thus expected that both the synthesis and the form of every specific biogenic mineral is genetically determined and controlled. An investigation of the mechanism of biomineralization has only become possible with the development of modern methods in molecular biology. Unicellular organisms such as magnetic bacteria, calcareous algae, and diatoms, all of which are amongst the simplest forms of life, are particularly suited to be investigated by these methods. Crystals and composites of proteins and amorphous inorganic polymers are formed as complex structures within these organisms; these structures are not known in conventional inorganic chemistry.