基于聚乙烯吡咯烷酮功能化磁性氧化石墨烯固相萃取鸡饲料中Cu(Ⅱ)、Zn(Ⅱ)、Cr(Ⅲ)、Cd(Ⅱ)和Pb(Ⅱ)离子

该文制备了聚乙烯吡咯烷酮(PVP)功能化的磁性氧化石墨烯(PVP/Fe3O4/GO)复合物,透射电镜和红外光谱结果显示,其表面含有大量的结合位点,可显著提高萃取效率.该复合物对Cu(Ⅱ)、Zn(Ⅱ)、Cr(Ⅲ)、Cd(Ⅱ)和Pb(Ⅱ)离子有强吸附作用,最大吸附容量分别为68.03、103.63、13.82、36.51、...     

Quantifying and Controlling the Composition and ‘Randomness’ Distributions of Random Copolymers

The effect of disparity in the reactivity ratios of monomer pairs on the composition distribution and microstructure of the resultant copolymer formed through free‐radical polymerization is quantified computationally. This correlation has been determined for the monomer pairs of styrene/methyl methacrylate and styrene/2‐vinyl pyridine for a variety of monomer feed ratios. These monomer pairs were chosen as they represent systems that have been utilized to experimentally examine the importance of copolymer architecture on its ability to compatibilize an immiscible polymer blend. Moreover, their respective random copolymers show conflicting results for this examination. The results of this work show that the difference in the reactivity ratios of styrene and 2‐vinyl pyridine copolymer (r₁ = 0.5, r₂ = 1.3) significantly broadens the composition and randomness distribution of the resultant copolymer. This breadth is not easily avoided as it evolves even in the early stages of the copolymerization. Conversely, for the styrene/methyl methacrylate pair, the reactivity ratios are similar (r₁ = 0.46, r₂ = 0.52) and this results in a copolymer with a narrow composition distribution and sequence distribution dispersion. Stopping the polymerization at early conversion further narrows both distributions. The presented results, therefore, provide fundamental information that must be considered when planning an experimental procedure to evaluate the relative importance of sequence distribution and composition distribution of a random on its application.     

方波伏安法间接测定饲料中的高含量磷

在pH=5．5的六次甲基四胺-盐酸缓冲溶液中,硝酸铅与磷酸根和氯离子反应,生成磷酸氯化铅复盐沉淀,用方波伏安法测定过量的铅离子,从而间接测定无机磷。在最佳测定条件下,当0．04mol／L硝酸铅标准溶液的用量为1．0mL时,峰电流ip与磷的质量浓度c在0．2～20μg／mL内呈良好线性关系,线性回归方程为ip=-2．39c 54．82,相关系数为0．9876,检出限为0．085μg／mL。用于饲料中磷含量的测定,测定结果的相对标准偏差为1．24％～2．44％,加标回收率为95％～99％。     

日本产在线气相色谱仪柱填料的国产化

介绍了用于监测环氧丙烷生产车间原料气组成的日本产在线气相色谱仪柱填料国产化的研制工作。经大量的测试与比较,选出了４种固定相用以代替原进口柱内填充物,经模拟与现场测试,效果好。     

MP-AES法测定水产饲料中多种金属元素

应用微波等离子体发射光谱(microwave plasma-atomic emission spectrometry, MP-AES)技术, 建立水产饲料中铜、铁、锰、锌、钾、钠等元素MP-AES分析方法。样品采用干灰化法消解, 开展了方法学研究试验, 同时与AAS和ICP-AES方法进行比对, 并完成FAPAS能力验证样品和标准物质确证试验。通过优化MP-AES仪器的各项参数, 在所选定的条件下, 各元素的线性相关系数在0.999以上, 检出限在0.4～3.9 mg·kg-1之间, 加标回收率在103%～112%之间, 精密度试验相对标准偏差在0.2%～0.6%之间;测定结果与AAS法、ICP-AES法比对, 单因素方差分析(α=0.05)各元素P值在0.065～0.438之间, 均大于0.05, 无显著性差异;FAPAS奶牛饲料能力验证和灌木枝叶(GBW07602)标准物质确证试验的各元素测定值均在参考值范围内。结果表明, 所建立的方法简单、快速, 线性范围宽, 具有良好的准确性和精密度;MP-AES无需使用乙炔、氩气, 安全、经济、环保, 能降低检测成本、提高检测效率, 可替代AAS、ICP-AES法测定水产饲料中的六种金属元素, 为水产饲料的质量控制提供理想的元素分析方法。     

Evaluation of the capabilities of atmospheric pressure chemical ionization source coupled to tandem mass spectrometry for the determination of dioxin-like polychlorobiphenyls in complex-matrix food samples

The use of the novel atmospheric pressure chemical ionization (APCI) source for gas chromatography (GC) coupled to triple quadrupole using tandem mass spectrometry (MS/MS) and its potential for the simultaneous determination of the 12 dioxin-like polychlorobiphenyls (DL-PCBs) in complex food and feed matrices has been evaluated.     

中华绒螯蟹对常用饲料原料氨基酸的消化率

用Cr2O3间接测定法测定了中华绒螫蟹对秘鲁鱼粉、国产鱼粉、豆粕、麦麸、四号粉、虾肉壳粉、啤酒酵母粉等7种常用饲料中蛋白质和氨基酸的表现消化率．结果表明，中华绒螫蟹对这7种原料的蛋白质消化率分别为：90．45％、89．41％、8525％、69．05％、78．45％、89．65％和83．95％；总的氨基酸消化率为：91.83％、92．23％、86．33％、79，29％、79．86％、91．29％和84．99％．动物性原料的消化率均高于植物性原料．经分析，蛋白质和氨基酸的消化率与原料中的粗纤维含量呈负直线相关关系（rp＝－0．6672P＜0．1，rA=－0．8763，P＜0．01）．     

CH4-CO2两步反应直接合成含氧有机物的研究——添加氢的影响

 以热力学分析和动力学分析为基础，设计了几种实现CH4－CO2低温转化直接合成含氧有机物的混氢进料方式，通过实验对这些进料方式进行了初步探讨，并考察了甲烷活化及二氧化碳反应过程中混氢比例的影响．结果表明，与CH4／CO2进料方式相比，几种混氢进料方式都能提高乙酸收率，但需要很好地控制二氧化碳加氢反应．在甲烷活化过程中混氢，13．8％的氢气比例对甲烷的转化最有利，乙酸收率可达最高；在二氧化碳反应过程中混氢，混氢比例为50％时乙酸收率最高．催化剂的催化特性与其反应前后表面特征的变化相吻合．     

流动注射-化学发光法测定猪饲料中的吡喹酮

基于吡喹酮对Luminol-NaIO_4化学发光体系有较强的抑制作用,并结合流动注射分析技术,建立了测定吡喹酮的流动注射-化学发光(FI-CL)新方法。在最佳实验条件下,吡喹酮在4.0×10~(-8)～1.0×10~(-6) mol/L浓度范围内与相对化学发光强度呈良好的线性关系,该方法对测定吡喹酮显示出较高的灵敏度,检出限(LOD,3σ)为9.9×10~(-9) mol/L。对2.0×10~(-7) mol/L的吡喹酮平行测定11次,其相对标准偏差(RSD)为1.4%。采用该方法对猪饲料样品进行加标实验,回收率为98.5%～100%。该方法已经成功用于猪饲料样品中吡喹酮的测定。     

European intercomparison study for the determination of fumonisins in maize

Fumonisins are mycotoxins occurring largely in maize and maize products, which cause animal diseases, such as equine leukoencephalomalacia and porcine pulmonary edema, and may also induce liver cancer on experimental rats. The European Commission Standards, Measurements and Testing (SMT, formerly BCR) Programme, has sponsored a project to improve analytical methodologies for the determination of the two major fumonisins (fumonisin B1 and fumonisin B2) in maize materials. The project involved the following steps: i) the preparation of a blank and a maize material contaminated with fumonisins Bl and B2; ii) a preliminary study of the -irradiation conditions for sterilization; iii) homogeneity and stability studies of the maize materials; iv) an intercomparison study for fumonisins analysis in the above materials with the involvement of 24 European laboratories, most of which have national or international responsibilities for foodstuff and/or feedstuff quality control. Results of the intercomparison study are presented together with the homogeneity and stability data relevant to the maize materials.