气相色谱法测定塑料奶瓶中迁移出的双酚A

本文介绍了塑料奶瓶(以聚碳酸酯为主要材质)中迁移出双酚A的气相色谱检测法。样品用食品模拟物(水)浸泡后,浸泡液经固相萃取(SPE)富积,五氟丙酸酐(PFPA)衍生后用GC-ECD检测。该方法的最低检测检出限为0.2μg/L,在0.2μg/L～50μg/L的线性范围内,相关系数r=0.9994。三种不同添加水平,三次平行实验平均回收率为92.3%～98.5%。方法的精密度(RSD)为3.35%～5.96%。该方法灵敏度高,准确,可靠,适用于聚碳酸酯奶瓶中迁移出微量双酚A的检测。     

食品罐内涂中双酚 A 检测方法的对比分析

目的研究金属食品罐内涂材料中双酚A的迁移。方法采用HPLC-FD和GC-MS法对食品罐内涂中双酚A迁移进行分析。结果在检测双酚A迁移的实验中,HPLC法回收率范围为92.6%~102.4%,线性相关系数为0.9998,精密度为4.0%,质量浓度的检测限为1.2μg/L;GC-MS法回收率范围为84.8%~103.2%,线性相关系数为0.9944,精密度为4.5%,质量浓度的检测限为0.03 mg/L。参考相关文献对分别采用HPLC-FD,UPLC-DAD,GC-MS,UPLC-MS检测双酚A迁移量的4种方法进行了对比分析。结论 HPLC-FD法具有检测限低、精密度高、随机误差小、稳定性好、适用范围广、前处理简单以及检测成本低廉等优点,是双酚A迁移的首选检测方法。     

同位素内标-UPLC-MS/MS法检测易拉罐啤酒中双酚A含量

目的 为了提高金属易拉罐啤酒中双酚A(BPA)的检测能力,建立一种基于同位素内标的超高效液相色谱-串联质谱分析方法。方法 样品经超声处理后除去CO2,随后添加内标物BPA-¹³C12,用超高效液相色谱-串联质谱法进行检测分析,采用内标法定量。结果 经同位素内标标准曲线校正,方法的定量限为1.00 μg/L,线性方程为y=1.73x+0.206,线性相关系数为0.9992,相对标准偏差为4.68%～6.63%,加标回收率为91.0%～109%。使用该方法对厦门市市售6种易拉罐啤酒样品进行了BPA污染物迁移量检测,结果显示6种啤酒中均检出BPA,平均质量浓度为1.48 μg/L。结论 此方法具有前处理简便快捷、检测限高、灵敏度高、准确度好等特点,能够满足金属易拉罐啤酒中低含量BPA的检测要求。     

双酚S迁移量的快速检测及迁移规律研究

目的研究聚醚砜中双酚S迁移量的快速检测方法,以及双酚S的迁移规律。方法以液相色谱-质谱法(LC-MS)快速测定模拟液乙醇(体积分数为50%)、乙酸(质量浓度为30 g/L)及水中双酚S的迁移量,并以此为基础,研究不同的介质、温度、时间、厚度等因素对双酚S迁移规律的影响。结果该法对双酚S的检出限为2.0μg/L,定量限为6.0μg/L,在模拟液水、乙醇(体积分数为50%)、乙酸(质量浓度为30 g/L)中的加标回收率分别为95.2%~102%,97.3%~102%,96.3%~102%,相对标准偏差分别为2.6%~4.2%,2.6%~4.0%,3.3%~4.7%;在相同条件下,双酚S在乙醇(体积分数为50%)中的迁移量最大,其迁移量顺序为乙醇(50%)乙酸(30 g/L)水,同时符合温度越高则迁移量越大、厚度越大迁移量越高的规律。结论采用液相色谱-质谱法检测双酚S,具有操作简便、灵敏度高、重复性好、结果准确等特点;食品模拟物的属性是影响双酚S迁移行为的重要因素,同时,温度和厚度也影响着双酚S在PES中的迁移。     

三重串联四级杆液质联用仪测定塑料杯中双酚A迁移量方法研究

建立了三重串联四级杆液质联用仪法测定塑料杯中双酚A(BPA)迁移量的分析方法。塑料杯经4种模拟液(水、3%乙酸水溶液、10%乙醇溶液和异辛烷)浸泡后,以ZORBAX Eclipce XDB-C18色谱柱分离,进行LC-MS/MS多反应监测模式下定性及定量分析。LC-MS/MS定量限为1.5μg/kg,线性范围为10~500ng/L,相关系数r2=0.9991,平均回收率为78.60%~97.92%,相对标准偏差为2.58%~7.65%(n=6)。     

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。     

食品接触材料中壬基酚和辛基酚的测定与风险分析

目的研究食品接触材料中壬基酚和辛基酚的含量和迁移量的情况,并分析食品暴露风险。方法采用液相色谱-质谱联用法建立食品接触材料中壬基酚和辛基酚含量和迁移量的检测方法,并对相关检测数据进行统计分析。结果在优化条件下,壬基酚和辛基酚在5~200μg/L范围内线性关系良好,相关系数均大于0.999,壬基酚和辛基酚含量和迁移量的检测方法定量下限分别为0.1 mg/kg和10μg/kg,在添加水平为10,100,200μg/L时,样品中壬基酚和辛基酚含量的平均加标回收率为85.6%~89.2%,迁移量的回收率为94.3%~100.6%,相对标准偏差均小于15%。对30批次保鲜膜和复合包装袋样品进行检测,结果显示,6批次样品检出壬基酚或辛基酚,占总体样品的20%;其中1批次样品检出壬基酚迁移量,占阳性样品的16.7%。结论保鲜膜和复合包装袋可能含有壬基酚和辛基酚,且容易迁移到食品模拟物中,迁移量随着温度的升高和时间的延长而增加。保鲜膜和复合包装袋中的壬基酚和辛基酚存在一定风险,应引起足够重视。     

高效液相色谱-三重四级杆质谱法测定豆制品中二甲基黄、二乙基黄

建立一种同时测定豆制品中二甲基黄、二乙基黄的高效液相色谱-三重四级杆质谱(HPLC-MS/MS)方法。对提取溶剂及色谱条件进行优化,粉碎后的样品经乙腈提取,提取液以HPLC-MS/MS测定,外标法定量。二甲基黄、二乙基黄在3 min内流出并完全分离,两者在0.05~10μg/L范围内相关系数r2均大于0.999,二甲基黄在0.5~50μg/kg的加标回收率为90.0%~93.4%,RSD为0.5%~5.1%,二乙基黄在0.5~50μg/kg水平的加标回收率在84.6%~93.8%,RSD为1.1%~4.6%,检出限两者均为0.2μg/kg。该方法操作简捷、准确度和精密度高,适用于豆制品中二甲基黄、二乙基黄的检测。     

食品包装塑料中双酚F和双酚S迁移量测定的优化及分析

目的 优化液相色谱串联质谱测定塑料制品中双酚F和双酚S迁移量的方法。方法 通过色谱条件及质谱条件的优化,迁移实验所得食品模拟物经C18柱分离、甲醇-氨水洗脱、多反应模式监测、外标法定量。结果 优化条件下,双酚F和双酚S线性关系良好,水基模拟物的检出限为4μg/L和0.2μg/L、定量限为10μg/L和0.5μg/L,油基模拟物的检出限为20μg/kg和1μg/kg、定量限为50μg/kg和2.5μg/kg,回收率为89.2%～105.5%,RSD值为1.42%～6.18%。结论 该法准确、灵敏,适用于食品包装塑料双酚F和双酚S迁移量的测定。     

加速溶剂萃取气相色谱-质谱法检测土壤中双酚A

建立加速溶剂萃取后利用气相色谱-质谱法测定土壤中双酚A的检测方法。样品前处理采用加速溶剂萃取,经硅胶柱净化,以HP-5MS色谱柱,采用气相色谱-质谱联用全扫描和选择离子扫描进行分析。结果表明:双酚A在0.1~10.0 mg/L的质量浓度范围内,线性良好,相关系数为0.999 3;方法检出限为0.01 mg/kg(S/N=3)。在0.1,1.0,10 mg/kg这3个加标水平下,样品的平均回收率为82.5%~101.7%,相对标准偏差(RSD)≤3.3%。该方法简便快速,灵敏度及准确度高,可用于土壤中双酚A的分析测定。     

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.     

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.     

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.……     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.