顶空-气相色谱法测定溶剂型油墨中22种有机溶剂

目的 建立同时测定现代溶剂型油墨中22种溶剂残留量的检测方法,为溶剂型油墨溶剂残留量的监管提供技术支持。方法 通过优化混合标准工作溶液的配制,采用优化的色谱条件,用HP-INNOWAX毛细管柱分离待测化合物、外标法定量的顶空气相色谱方式检测溶剂型油墨的22种溶剂残留量。结果 22种溶剂均能较好的分离,且呈现良好的线性关系;相关系数均在0.999以上,检出限为0.000 21～0.000 55 mg/m²,回收率为85.92%～102.51%,精密度为0.46%～5.73%。结论 该方法分离度好、灵敏度高、精密度好、准确度高,在实际样品检测中,取得了良好的效果,可为溶剂型油墨溶剂残留量的监管提供技术支持。     

SPME-GC/MS法测定饮用水中除草剂

建立了饮用水中乙草胺、丁草胺和异丙甲草胺三种酰胺类除草剂的固相微萃取-气相色谱质谱测定的分析方法。对萃取纤维涂层、萃取时间与解吸时间、离子强度、搅拌速度及pH等实验条件进行了优化。用HP-5MS弹性石英毛细管柱经柱程序升温技术分离,并用质谱检测器检测,外标法计算含量。该方法对饮用水中乙草胺、丁草胺和异丙甲草胺的检出限分别为2.8ngL-1、3.2ngL-1、7.4ngL-1,精密度分别为5.6%、4.1%、7.9%,回收率为81%～102%。所测样品不含几种除草剂残留。本法简便、干扰小、检测效果好,可用于饮用水中除草剂残留量的检测。     

基于HS-GC-MS/MS法测定食品烘焙用纸中9种有机溶剂

目的 建立同时测定食品烘焙用纸包装中9种有机溶剂残留量(丁酮、苯、甲苯、对二甲苯、间二甲苯、邻二甲苯、乙酸乙酯、乙酸丁脂、正丁醇)的方法。方法 通过优化自动顶空(HS)-气相色谱(GC)-串联三重四级杆质谱(MS/MS)仪器的自动顶空进样器、色谱、质谱检测。采用优化条件,样品平衡温度为120 ℃,顶空平衡时间为30 min,用Thermo TG-WAXMS色谱柱分离化合物,进样分流比为25∶1,采用外标法定量,MRM(多反应监测模式)模式GC-MS/MS方式检测食品烘焙用纸。 结果 采用该方法能完全分离9种有机溶剂,且线性良好(相关系数在0.99以上),方法检出限为0.003～0.010 mg/m²,回收率为93.8%～101.5%,RSD范围为1.3%～3.5%。结论 该方法与气相色谱检验方法比较,更简单快捷,分离效果好,结果准确,检出限更低,可用于实际检测大批量食品烘焙用纸包装产品中9种有机溶剂残留量。     

高效液相色谱法同时测定茶叶中吡虫啉和除虫脲的残留量

建立了QuEChERS法净化样品,高效液相色谱法同时测定茶叶中吡虫啉和除虫脲的检测方法。茶叶样品经乙腈提取,加入聚酰胺净化,以乙腈和水为流动相进行梯度洗脱,采用C18色谱柱分离。吡虫啉和除虫脲的回收率为87.4%～112.1%,相对标准偏差为2.0%～4.2%,该方法前处理简单,分析速度快,稳定可靠,适用于茶叶中吡虫啉和除虫脲残留量的快速同时测定。     

顶空-气相色谱法测定托芬那酸中有机溶剂残留

目的:采用顶空-气相色谱法测定托芬那酸中甲苯和二甲基甲酰胺(简称DMF)两种有机溶剂的残留量。方法:采用顶空程序升温气相色谱法,顶空平衡温度100℃,平衡时间30min,色谱柱为DB-624毛细管柱,初始柱温为60℃,保持3min后以20℃/min的速率升温至200℃,保持4min。结果:甲苯和DMF在该色谱条件下线性关系、回收率、精密度和检测限均符合要求。结论:该方法操作简便,结果准确可靠。可用于托芬那酸产品中残留有机溶剂的测定。     

UPLC-MS/MS法测定虾蟹中4-己基间苯二酚的残留量

建立一种超高效液相色谱-串联质谱(UPLC-MS/MS)测定虾蟹中4-己基间苯二酚残留量的检测方法。样品经乙腈超声提取,C18固相萃取柱净化后,UPLC BEH C18色谱柱分离,多反应监测方式测定,外标法定量。结果显示:加标回收率在88.32%~92.08%之间,相对标准偏差RSD≤2.3%;以S/N=3计算,检出限为5.0μg/kg。该法灵敏度好、准确性高、精密度好、检出限低,适用于虾蟹中4-HR微量和痕量残留的测定。     

气相色谱法测定土壤中的六六六、滴滴涕

建立了土壤中六六六、滴滴涕残留量的气相色谱检测方法。样品经石油醚／丙酮（1：1）提取、浓硫酸净化，气相色谱分离后，电子捕获检测器检测，外标法定量。样品加标回收率在89．7％-113．6％之间，精密度RSD为1．4％-3．0％。结果表明，该法简便、灵敏、准确，适用于土壤中的六六六、滴滴涕残留量的分析。     

HPLC法同时测定青钱柳叶中绿原酸等4种多酚酸的含量

目的:建立青钱柳叶代用茶中绿原酸等4种多酚酸含量HPLC分析方法。方法:样品经过70%甲醇水溶液80℃水浴提取2小时,采用反相高效液相色谱外标法,色谱柱C18(250×4.6mm,5μm),流动相乙腈-0.1%磷酸水溶液(梯度洗脱),流速1.0ml/min,柱温30℃,进样量20ul,4种多酚酸检测波长326 nm。结果:新绿原酸(0～84ug/ml范围呈良好的线性关系,相关系数1,加标回收率98.86%,精密度RSD为0.79%);绿原酸(0～102ug/ml范围呈良好的线性关系,相关系数1,加标回收率104.5%,精密度RSD为0.76%);隐绿原酸(0～110ug/ml范围呈良好的线性关系,相关系数0.999,加标回收率98.73%,精密度RSD为0.72%);咖啡酸(0～64ug/ml范围呈良好的线性关系,相关系数1,加标回收率99.97%,精密度RSD为0.73%)。用此法检测青钱柳叶代用茶,其中绿原酸含量较高约2.0～19mg/kg;隐绿原酸和新绿原酸含量较低约0.2～1.5mg/kg;不含咖啡酸。结论:该方法可以同时完成4种多酚酸的有效分离、定性和定量,标准曲线线性关系良好、检测结果可靠、样品前处理简单、检测操作过程便捷,可以作为青钱柳叶代用茶质量控制的检测方法。     

气相色谱—质谱联用测定皮革中N,N-二甲基甲酰胺含量

本文建立了以乙酸乙酯为萃取溶剂,通过超声提取,气相色谱-质谱联用技术对皮革中N,N-二甲基甲酰胺残留量进行定性和定量的分析方法。该方法的回收率为95.93～101.83,检出限为1.50μg/mL。该方法前处理简单、快捷,准确度好、精密度高,可以适用于皮革等产品中N,N-二甲基甲酰胺残留量的定性筛查和精确测定。     

高效液相色谱法同时测定青钱柳叶中异槲皮素等5种黄酮单体的含量研究

目的:建立青钱柳叶代用茶中异槲皮素等5种黄酮单体含量的高效液相色谱分析方法。方法:样品经过70%甲醇水溶液80℃水浴提取2小时,采用反相高效液相色谱外标法,色谱柱C18(250×4.6mm,5μm),流动相乙腈-0.1%磷酸溶液(梯度洗脱),流速1.0ml/min,样品进样量20ul,柱温30℃,5种黄酮单体检测波长360 nm。结果:芦丁(0～2.04ug范围呈良好的线性关系,相关系数0.999,加标回收率96.60%,精密度RSD为1.49%);异槲皮素(0～1.23ug范围呈良好的线性关系,相关系数0.999,加标回收率97.23%,精密度RSD为1.09%);槲皮素(0～0.96ug范围呈良好的线性关系,相关系数0.999,加标回收率101.95%,精密度RSD为1.03%);山奈酚(0～1.05ug范围呈良好的线性关系,相关系数0.999,加标回收率103.31%,精密度RSD为1.11%);山奈素(0～2.22ug范围呈良好的线性关系,相关系数0.999,加标回收率98.69%,精密度RSD为1.13%);用此法检测青钱柳叶代用茶,其中异槲皮素含量较高约2.0～18mg/kg;槲皮素和山奈酚含量较低约0.02～0.4mg/kg;不含芦丁和山奈素。结论:该方法可以同时完成青钱柳叶中异槲皮素等5种黄酮单体的有效分离、定性和定量,标准曲线线性关系良好。该方法检测结果可靠、样品前处理简单、检测操作过程便捷、加标回收率高等特点,可以在青钱柳叶代用茶质量控制及产品开发实际检测中加以应用。     

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.     

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.     

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.……     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.