含油脂食品中邻苯二甲酸酯的前处理及其GC-MS测定方法

建立了15种邻苯二甲酸酯的提取-固相萃取净化-气相色谱/质谱检测分析方法。讨论了含油脂食品中邻苯二甲酸酯的提取、净化方法,优化了色谱分离条件。研究表明,该前处理方法具有较高的净化效率,且缩短了整个检验所需时间;15种邻苯二甲酸酯的方法线性范围为50～2000μg/L,相关系数均大于0.999,加标样品在200μg/L和2000μg/L两个浓度水平下,相对标准偏差在1.1%～11.2%范围,除邻苯二甲酸二甲酯较低外,样品加标回收率均在70%～120%之间。检测限在0.07～1.2μg/L范围(S/N=3)。     

高效液相色谱法测定3种邻苯类增塑剂检测条件的研究

选择邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二乙酯(DEP)、邻苯二甲酸二丁酯(DBP)3种标准物质为研究对象,建立了高效液相色谱法检测邻苯二甲酸酯的条件,对实验方法的准确程度进行了分析。结果表明,以甲醇-水为流动相,采用梯度模式洗脱,检测波长为225nm,柱温为30℃,流量为1.000mL/min,进样量为10μL时,可以很好地分离3种邻苯二甲酸酯,目标分析物质量浓度在0.5～100μg/mL范围之间时,得到的线性相关系数在0.999 96～0.999 98之间;重复性实验表明,10次实验的保留时间的相对标准偏差在0.0314%～0.0389%之间,峰面积的相对标准偏差在0.0942%～0.353%之间,DMP,DEP,DBP的方法检测限分别为0.0228,0.0277,0.0489μg/mL。     

HPLC检测猪肉组织中3种氟喹诺酮类药物残留

建立了HPLC-FLD同时检测猪肉组织中环丙沙星、单诺沙星、沙拉沙星等3种氟喹诺酮类药物.猪肉组织样品用磷酸盐水溶液提取,在C18固相萃取柱净化,采用乙腈-磷酸/三乙胺溶液作为流动相,荧光检测器检测(λα=280nm,λ(em)=450nm).这3种氟喹诺酮标准曲线的线性回归系数均在0.9999以上,检测线性范围环丙沙星、沙拉沙星为(2.5～500)μg/kg,单诺沙星为(0.5～100)μg/kg.猪瘦肉组织中这3种氟喹诺酮的平均加标回收率为79.9%～93.6%;相对标准偏差分别为2.54%、2.60%、2.51%.环丙沙星、沙拉沙星的最低检测限为2.5μg/kg,单诺沙星的最低检测限为0.5μg/kg.     

养殖水体中多氯联苯残留的气相色谱分析

建立了养殖水体中PCBs气相色谱检测方法,PCBs检测限量为31.3×10-3μg/L,10个单体检测限范围在0.879×10-3～5.92×10-3μg/L;当样品中添加0.02、0.05、0.1 mg/L的3个浓度梯度时,回收率范围在88.4%～98.0%,精密度范围在4.02%～12.04%。本方法具有灵敏度高、重复性和稳定性好、简单方便等特点,适合实验室分析。     

快速溶剂萃取-GC-MS/MS法测定经济作物土壤中的甲霜灵、嘧霉胺、戊唑醇等6种常用农药残留

建立一种利用快速溶剂萃取(ASE)-气相色谱-三重四级杆质谱仪检测经济作物土壤中甲霜灵、嘧霉胺、戊唑醇等6种农药的分析方法。样品经研钵研细,利用ASE进行提取,提取液经氮吹浓缩后,上GC-MS/MS进行检测,外标法定量。6种农药质量浓度在0.05～5μg/mL范围内线性关系良好,相关系数均大于0.995;检出限在0.005～0.023μg/mL;加标回收率在81.2%～108.7%之间;重复性(n=6)相对标准偏差在3.26%～4.40%之间。实验表明该方法具有操作简单、检测速度快、检出限低等优点,适用于经济作物土壤中多种农药残留的分析检测。     

顶空气相色谱法测定舒它蓝锌中N.N-二甲基甲酰胺和2-乙氧基乙醇

本文应用顶空进样方式,DB-624毛细管柱分离,FID检测器,程序升温模式,外标法定量测定脂溶性药物(舒它蓝锌)中N.N-二甲基甲酰胺和2-乙氧基乙醇的残留量。结果N.N-二甲基甲酰胺和2-乙氧基乙醇的线性范围分别为10～500μg/ml和2～100μg/ml,相关系数r分别为0.9997和0.9995;回收率分别在98.2%～111.2%和96.1%～107.1%之间,相对标准偏差(RSD)分别为3.9%和1.9%,最低检测浓度均为1.0μg/ml。     

配体交换色谱手性固定相法拆分与定量茶氨酸对映体

本文建立了配体交换色谱手性固定相法拆分与定量茶氨酸对映体的方法。色谱条件为:L-羟基脯氨酸键合手性柱;0.8mmol/L的硫酸铜-水溶液为流动相;波长254nm;流速1.0mL/min;柱温30℃。L-茶氨酸的进样量在0.08126～4.5144μg范围内峰面积与进样量之间呈现良好线性关系,加标回收率为97.26%～102.1%,检测限为0.02742μg,定量限为0.06503μg;D-茶氨酸的进样量在0.08250～4.5832μg范围内峰面积与进样量之间线性关系良好,加标回收率在97.07%～101.2%,检测限为0.02941μg,定量限为0.06982μg。该方法具有良好的稳定性和准确度。     

采用高效液相色谱法测定PET瓶装饮用水中双酚A及其迁移量

目的建立基于高效液相色谱技术的双酚A分析方法,用于快速准确检测襄阳市售5种PET瓶装饮用水塑料包装中的双酚A含量及其在饮用水中的迁移量。方法样品经前处理后,采用高效液相色谱-紫外检测器方法分离检测,选择ODS-C18色谱柱(4.6 mm×150.0 mm,5μm),流动相为甲醇-乙酸铵溶液(体积比为50∶50),柱温为30℃,流速为1 mL/min,检测波长为280 nm。结果双酚A的检出限为0.004μg/mL,在0.02μg/mL质量浓度条件下的相对标准偏差为4.32%,在线性浓度为0.01～200μg/mL内的检测信号与双酚A浓度具有良好的线性相关性(r20.9999),方法分析性能满足国标限量要求。襄阳市售主要品牌PET瓶装饮用水包装中虽均含有一定量的双酚A,但饮用水中未检出双酚A。PET包装中双酚A在0.4,4,40μg/g等3个加标水平的回收率为70.30%～113.00%,饮用水中双酚A在0.1,1,10μg/g等3个加标水平的回收率为90.00%～119.00%,加标回收结果良好。结论此方法简便、准确、高效,适用于PET瓶装饮用水包装中双酚A含量及迁移量的分析。     

乙酸乙酯加速溶剂萃取-高效液相色谱法测定土壤中的多环芳烃

本文建立了以乙酸乙酯为萃取剂的简便、有效的加速溶剂萃取-高效液相色谱荧光(ASE-HPLC-FLD)测定土壤样品中15种多环芳烃(PAHs)的方法。取样量为5g,荧光检测方法检出限为0.03μg/kg～0.4μg/kg,加标回收率在68.1%～110.0%之间,相对标准偏差为2%～10%(n=5)。     

一种自动石墨消解-ICP-MS法监测工业区土壤中微量砷、汞、硒、锑元素残留方法的建立

建立电感耦合等离子体质谱法监测工业区土壤样品中砷、汞、硒、锑4种微量元素残留的分析方法。利用全自动石墨消解仪消解工业园区土壤样品,盐酸-硝酸-氢氟酸体系作为消解酸体系,按照程序设置进行密闭消解,消解液用3%稀硝酸定容,电感耦合等离子体质谱仪定量检测砷、汞、硒、锑4种元素残留量。4种元素质量浓度在0.02～10μg/L范围内线性关系良好,相关系数(r2)0.995;4种元素加标回收率范围为84.5%～107.2%;检出限:砷0.001 8μg/L、汞0.003 4μg/L、硒0.007 4μg/L、锑0.001 0μg/L;精密度相对标准偏差RSD(n=6)在1.35%～3.51%之间,重复性相对标准偏差RSD(n=6)在2.47%～4.89%之间。结果表明,该方法具有前处理快速、检出限低、重复性好、检测结果准确可靠等优点,适用于工业园区土壤中微量元素残留的检测。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.