气球中N-亚硝胺及其前体物迁移量的测定与NDMA的儿童致癌暴露风险分析

用Sep-Pak AC2串联Dry cartridges固相萃取小柱对气球中的7种挥发性N-亚硝胺进行分离净化,并用气相色谱-串联质谱法对其进行定性与定量分析。方法对气球中N-亚硝胺及其前体物的检出限分别为1.25μg/kg和5.00μg/kg。对空白样品进行添加量为2.5μg/kg的加标回收实验,回收率为85%～103%,RSDs(n=3)≤4.6%。分析的气球样品中,N-亚硝基二甲胺(NDMA)及其前体物的检出频率最高;其次是N-亚硝基二乙胺(NDEA)及其前体物;N-亚硝基吗啉(NMOR)、N-亚硝基二丙胺(NDPA)和N-亚硝基哌啶(NPIP)及其前体物均未检出;7种N-亚硝胺及其前体物的总迁移量分别为0.036～0.964 mg/kg和0.259～8.436 mg/kg。6个月～4岁儿童通过口直接接触单个气球样品造成的NDMA的暴露量集中在0.010～0.030mg/kg体重,具有潜在的致癌暴露风险。     

乙二胺四乙酸辅助水热法合成NaYF_4纳米晶

用络合剂乙二胺四乙酸(EDTA)辅助水热法合成了NaYF4纳米球和微米棱柱,通过控制反应条件得到了立方相和六方相纳米晶体;采用X射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)及荧光光谱仪(PL)分析了产物的结构、形貌及发光性能.结果表明,络合剂EDTA和氟化物的物质的量对NaYF4的形貌和粒度有很大影响,且产物的荧光性能呈现出尺寸依赖性.     

高效液相色谱法同时测定生物质乳酸发酵液中有机酸及糖类化合物

建立了高效液相色谱(HPLC)同时测定生物质乳酸发酵液中有机酸及糖类的分析方法。使用Bio-Rad Aminex HPX-87H色谱柱,以5 mmol/L的H2SO4为流动相,在柱温55 ℃,流速0.6 mL/min条件下,采用示差折光检测器进行检测。结果表明,该方法可在17 min内实现发酵液中各种有机酸和糖类化合物等的完全分离与定量,6种有机酸和3种糖类化合物在0.15～5.19 g/L范围内的线性关系良好,回归方程的线性相关系数在0.9998以上。将该法用于米根霉发酵液的检测,两个水平的加标回收率为96.91%～103.11%,相对标准偏差(n=6)为0.81%～4.61%。该法适用于微生物发酵液中多种有机酸和糖类的快速、高效分离和定量测定。     

离子色谱同时分离测定三氟甲烷磺酸根,氟硼酸根及常见无机阴离子

建立了离子色谱-直接电导检测同时测定三氟甲烷磺酸根,氟硼酸根及常见无机阴离子(F-,Cl-,Br-,NO3-,SO24-)的方法。实验采用Shim-pack IC-A3阴离子交换色谱柱,分别选用对羟基苯甲酸-三(羟甲基)氨基甲烷-硼酸,邻苯二甲酸-三(羟甲基)氨基甲烷,邻苯二甲酸氢钾为淋洗液,考察了淋洗液种类,浓度及色谱柱温度对分离测定三氟甲烷磺酸根,氟硼酸根及常见无机阴离子的影响。最佳色谱条件为:以1.2mmol/L邻苯二甲酸氢钾为淋洗液,柱温30℃,流速1.0mL/min。在此条件下,可同时基线分离7种阴离子,且色谱峰形对称。所测阴离子的检出限(S/N=3)为0.02～1.88mg/L,保留时间和峰面积的相对标准偏差(n=5)分别小于0.17%和2.05%。应用本方法测定离子液体中三氟甲烷磺酸根,氟硼酸根及常见无机阴离子,加标回收率在97.0%～102.8%之间。本方法简单,准确,可靠,具有较好的实用性。     

Evolution of self-diffusion and local structure in some amines over a wide temperature range at high pressures: a molecular dynamics simulation study

Self-diffusion and structural properties of ammonia, methylamine and trimethylamine have been studied by molecular dynamics simulation in the temperature range between the melting pressure curve and 700 K at pressures up to 400 MPa. The calculation results agree well with the experiment, which suggests that one can use the simulation method as a powerful tool to obtain self-diffusion coefficients over wide range of temperatures and pressures, under which it is rather difficult for experiments. The local structures of such fluids are investigated by calculating radial distribution functions (RDFs), the numbers of hydrogen bonds and coordination numbers. The correlation between self-diffusion and structural properties, and the influence of temperature and pressure on them are discussed. The simulation results demonstrate that the temperature effects are more pronounced than the pressure effects on self-diffusion and structural properties, and the effect of hydrogen bonding on the translational dynamics in any of these systems is a minor factor, while it is mainly affected by the close packing of amine molecules.     

Chromatographic fingerprint study on Evodia rutaecarpa (Juss.) Benth by HPLC/DAD/ESI‐MSn technique

The LC–ESI‐MSⁿ method was developed for the analysis and characterization of alkaloids in the extract of E. rutaecarpa (called Wuzhuyu in Chinese). Thirty‐six batches of Wuzhuyu from different locations of China were investigated and the common fingerprinting profile was established with a professional analytical software recommended by the State Food and Drug Administration. Fifteen chemical components of the common peaks were identified by multi‐stage MS. The effects on the chromatographic profile resulting from different collecting locations, harvesting times or storage times were studied. Hierarchical clustering analysis and principal components analysis were also performed to classify and differentiate the 36 batches of the samples. As a result, those which had same chemical properties were sorted into one cluster, which was very useful in evaluating and controlling the quality of Wuzhuyu.     

新型含2-取代-1,3-噻唑烷环的噻唑酰胺类化合物的合成与生物活性研究

为了寻找新的含噻唑杂环的先导化合物,利用¨(2-氰基亚胺基-1,3-噻唑烷-3-基)甲基]-2-氨基噻唑与取代苯甲酰氯(或乙酰氯)在吡啶存在下发生缩合反应,合成了19个新型含2-取代-1,3-噻唑烷环的噻唑酰胺类化合物4.经1HNMR和元素分析对目标化合物的结构进行了表征,经MS进一步证实了化合物4s的结构,并通过X射线单晶衍射分析测定了化合物4a的晶体结构.对所合成的目标化合物进行了生物活性测试,部分化合物表现出一定的杀菌和植物生长调节活性.     

Preparation and evaluation of hydrophilic C18 monolithic sorbents for enhanced polar compound retention in liquid chromatography and solid phase extraction

Hydrophilic C18 monolithic polymer sorbents were synthesized for use in solid phase extraction (SPE) and in capillary liquid chromatography (LC). The approach involved incorporating both hydrophobic and hydrophilic monomers into a monolithic material, by copolymerization of stearyl methacrylate (SMA), poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) and ethylene dimethacrylate (EDMA) in the presence of selected porogens, to produce translucent mesoporous monolithic materials in bulk (SPE) or white macroporous monoliths inside fused silica capillary columns (capillary LC). A capillary column containing one of the hydrophilic C18 monoliths (i.e. poly(SMA-co-PEGMEMA-co-EDMA) with 15% (w/w) PEGMEMA) demonstrated nearly 35% reduction in retention of polycyclic aromatic compounds and greater than 40% increase in retention of phenols compared to a hydrophobic C18 monolithic column. In addition, the hydrophilic monolith demonstrated significantly improved resolution of phenols. Similar monolithic materials prepared in bulk were ground and sieved to obtain 45-65 μm particles with desired rigidity for SPE. To achieve optimum extraction performance for phenols, several parameters, including sample pH and volume, and eluent type and volume, were investigated. Under optimized experimental conditions, the method demonstrated good sensitivity (1.6 ng/mL LOD) and linearity (R(2)>0.97 for 10-200 ng/mL). Again, incorporation of 15% (w/w) PEGMEMA in the monolith increased the extraction efficiency of phenols in water from approximately 20% to 67-92% compared to a hydrophobic C18 monolithic material. Increased wettability of the sorbent by the aqueous sample matrix and the presence of hydrogen-bonding interactions are responsible for the improved retention of polar compounds.     

高效液相色谱法同时测定秋葵干蔬中的脂溶性维生素A、E、K3

建立了同时测定秋葵干蔬中脂溶性维生素A、E、K3的反相高效液相色谱法.样品皂化后,采用C18色谱柱(150 mm×4.6 mm,5μm i.d.)进行分离,以甲醇为流动相,流速1.0 mL/min,二极管阵列检测器(DAD)在325、290、244 nm波长下同时检测,外标法定量.结果表明,脂溶性维生素A、E、K3在0...     

表面活性剂类多肽A6KA6K的自组装及机理研究

为了研究表面活性剂类多肽疏水链段长度及亲疏水氨基酸比例对其自组装结构的影响,本文设计了一种表面活性剂类多肽A6K的二倍体A6KA6K。圆二色谱分析表明的二级结构主要为无规卷曲结构并伴有少量的α-螺旋;透射电子显微镜和动态光散射分析表明,其在水溶液中能自组装形成纳米囊泡状结构。芘荧光分子探针研究表明自组装体存在疏水微区域将芘分子包裹在其中,证明了这种多肽在溶液中可形成胶束类的自组装体,并计算了其临界胶束浓度。相比已报道的表面活性剂类肽A6K,本文设计的肽序列A6KA6K由于在较长疏水链段区域中存在亲水性氨基酸K,对疏水相互作用有影响,使得含有14个氨基酸的肽自组装形成纳米囊泡状结构。