An HPLC method for the determination of selected amino acids in human embryo culture medium

A method for the determination of selected amino acids in culture medium using HPLC with fluorescence detection is described. Twenty hours after intra‐cytoplasmic sperm injection, one randomly selected zygote was transferred to the culture medium. After incubation (72 h after fertilization), the culture medium in which the embryo was incubated and blank medium was immediately stored at −80°C. Filtered medium samples were derivatized with ortho ‐phthalaldehyde (naphthalene‐2,3‐dicarboxaldehyde), forming highly fluorescent amino acids derivatives. Reverse‐phase columns (LichroCART, Purospher STAR RP_18e or Ascentis Express C₁₈) were used for the separation. The derivatives were analyzed by gradient elution with a mobile phase containing ethanol and sodium dihydrogen phosphate. The analytical performance of this method is satisfactory for all amino acids; the intra‐assay coefficients of variation were <10% and quantitative recoveries were between 95.5 and 104.4%. Changes in the levels of selected amino acids before and after human embryo cultivation were observed. After embryo incubation, the levels of all amino acids in the medium were increased, apart from aspartate and asparagine. After the cultivation of some embryos, amino acids which were not part of the medium were detected. Low amino acids turnover was observed in some embryos.     

不同溶剂中钯电极上硝基苯游离基的现场检测

本文通过将钯电解池安装在高灵敏度的电子自旋共振（ＥＳＲ）腔内，采用流动电解法现场检测到硝基苯在不同溶剂中电还原时硝基苯游离基的存在。在不同溶剂中，硝基苯游离基电子自旋共振产生的谱线分辨率不同，因而说明溶剂对硝基苯游离基有影响，且这些溶剂中钯电极上硝基苯的电还原必须经过硝基苯游离基中间体这一步。     

1,2,1′,2′-双蒽醌-3,12-二羧酸的还原反应

1,2,1＇,2＇-双蒽醌-3,12-二羧酸(1)是一个π-共轭体系芳环化合物,内环酮基由于受空间效应和共振效应的影响,不能被还原成相应的醇或相应的碳氢基团,却成了不常见的内“双氧桥”化合物(4)。化合物2,3,4的结构已经确定,并对1的还原机理进行了初步讨论。     

Simultaneous emissions from T2 and T1 states of naphthalene moiety in a specially designed naphthalene cryptand

We report here the photophysical properties of a naphthalene derivative of a specially designed cryptand system (L). The system exhibits the unusual phenomenon of emission from T₂ and T₁ states of naphthalene which has been attributed to the inherent rigidity of the system. The results obtained have been analysed by comparison with two other model systems where the flexibility of the fluorophore unit with respect to the receptor moiety have been varied.     

交联萘沥青的组成与结构特征

萘与硫在较低温度下交联聚合，制得了可溶性好、残炭值高、软化点较低，流动性良好的交联萘沥青。结构分析发现，此沥青分子量分布较窄，主要由三到四个萘分子交联而成，推测其反应机理，估计聚合物经萘环侧位交联成环而形成长链状硫杂环类结构。     

Orientational ordering and the effect of dimerization in wall-adjacent liquid layers

Comparative investigations of electronic-vibrational absorption spectra of thin layers of nonmesogenic liquids formed on dielectric and conductive substrates were carried out. Results are interpreted within the framework of Mayer–Saupe theory that takes into account the dispersion and the dipole–dipole interaction between molecules and molecular associates, and the influence of the field of surface forces as well.     

Electrochemical properties of niosomes‐modified Au electrode and its interaction with 1‐anilino‐8‐naphthalene‐sulfonate

The gold electrode was modified by noisomes, prepared by sonicating the mixed solution of PEG 6000/Tween 80/Span 80/H₂O. Electrochemical cyclic voltammetry (CV) and impedance spectroscopy (EIS) were performed for characterizing the modification. The construction of multilayer films of octadecanethiol (ODT)‐niosomes had almost no pinholes, which elicited that niosomes‐coated electrode through ODT assembly was more effective immobilization compared to direct modification method. A large semicircle formation in the entire range of frequency indicated the complete electron‐transfer control for the redox reaction, implying a perfect blocking behavior. The Nyquist plot was consisting of two depressed semicircles after storage for 36 h in air, which implied a progressive and uniform construction manner, as expected for porous coatings. The modified electrode was used to investigate the interaction between 1‐anilino‐8‐naphthalene‐sulfonate (ANS) and noisomes. It was found that the low‐frequency semicircular arcs increase in diameter, indicating that the increase in the resistance R_p attributed mainly to the niosomes/solution interface. It was due to the binding of ANS to the niosomes‐modified electrode surface, exhibited against diffusing species through the pores. Copyright © 2009 John Wiley & Sons, Ltd.     

Directly suspended droplet microextraction in a rotating vial

In this paper, a novel suspended droplet microextraction method was developed for the detection of trace of organic compounds in water samples. The process was executed in a rotating extraction vial without the use of a stir bar. A single drop of octan-1-ol placed on top of the water sample was used as the solvent. The droplet remained on top of the water sample as a thin layer with an expanding surface area during the extraction stage, while during the sampling stage, the droplet was collected and sampled by inserting a needle. The volume of the microdroplet used was 3 μL or less, to ensure high organic compound sensitivity. The microextraction experimental setup was simple, utilizing centrifugal forces and possesses the advantages of low cross-contaminant/interference and applicability to water samples apt to emulsification. Nitrobenzene was selected as a model organic compound, and samples were analyzed using gas chromatography (GC) or UV-vis spectrometry. Analysis of the microextraction method results showed a relative standard deviation (RSD) less than 3.82%.     

Hβ/Al-SBA-15介微孔复合分子筛负载Ni-W催化剂对萘加氢裂化制BTX的催化性能

采用后合成法制备Hβ/Al-SBA-15复合分子筛,利用XRD、N_2吸附、Py-IR、NH_3-TPD、SEM和TEM等手段进行表征。用浸渍法将Ni-W活性组分担载在Hβ/Al-SBA-15载体上,制备Ni-W/Hβ/Al-SBA-15催化剂,以萘为模型化合物,考察该催化剂的加氢裂化性能。结果表明,所合成的Hβ/Al-SBA-15复合分子筛既有介孔结构又有微孔结构,并同时具有B酸和L酸中心,酸性强于SBA-15。具有适度酸性位和介微孔结构的Ni-W/Hβ/Al-SBA-15催化剂,对萘加氢裂化具有较高的萘转化率和BTX选择性,分别为96%和61.1%。     

微波萃取/GC-MS法对电子电气产品中多氯萘的测定

建立了微波萃取/GC-MS法检测电子电气产品中多氯萘的方法。将破碎后的样品以甲苯为溶剂进行微波萃取,萃取液经硅胶小柱净化、平行蒸发定量浓缩后采用气相色谱-质谱法测定多氯萘的含量,外标法定量。优化了样品前处理条件,包括前处理方式、微波萃取溶剂、萃取时间,以及净化小柱的选择。对于8种含不同氯原子数的多氯萘,在1~50 mg/L范围内,线性关系良好,相关系数均大于0.995;方法定量下限为0.2~1.0 mg/kg,相对标准偏差为2.7%~7.2%,回收率为77%~112%。该法操作简便、分析迅速、结果准确,可以满足对电子电气产品中多氯萘的定性确证和定量分析。