火焰原子吸收光谱法测定红车轴草及其提取物中铁和锰

应用火焰原子吸收光谱法(FAAS)测定了红车轴草及其提取物中铁和锰的含量,试验了仪器的工作条件并予以优化,经干燥和粉碎的试样于瓷坩埚中用浓硝酸处理,经蒸发至干,于马弗炉中在500℃灼烧1 h重复处理一次后用0.2 mol.L-1HCl浸取坩埚中残渣,所得溶液进行FAAS测定,两元素的线性范围为0.50~4.00 mg.L-1(铁)和0.20~3.00 mg.L-1(锰),相关系数依次为0.999 6和0.999 0。根据标准曲线斜率算得两元素的测定灵敏度依次为0.028和0.011 mg.L-1/1%。试验得铁的回收率为98.9%,锰的回收率为96.2%,平行5次测定一红车轴草试样中铁及锰量,对平均含铁量为67.0μg.g-1的相对标准偏差(RSD)值为2.45%,平均含锰量为7.8μg.g-1的RSD值为2.10%。     

火焰原子吸收光谱法测定奶类食品中铜锌铁锰

对火焰原子吸收光谱法(FAAS)测定乳品中铜、锌、铁、锰的条件进行了试验和优化。对方法的干扰因素,准确度和精密度也作了试验。乳品试样用HNO3-HClO4混合酸消化处理。所得溶液蒸发至近干,用稀硝酸(1 99)溶解盐类,溶液经定容后供作FAAS测定。对4元素的测定时,吸光度与浓度之间呈良好线性关系,所求得的线性回归方程及其相关系数可作佐证。应用所提出的方法测定了3种不同的乳制品中的铜、锌、铁及锰,测定值的RSD值均小于3.5%,回收率在93.0%~103.0%之间。     

美洲商陆对锰毒生理响应的FTIR研究

在一定Mn浓度梯度处理下(0,0.125,0.25,0.5,1 g·kg-1),超积累植物——美洲商陆(Phytolacca americana)不同组织器官的傅里叶变换红外光谱(FTIR)图谱发生了变化。其中,茎组织在3 336和2 916 cm-1处峰高先上升后下降,反映了有机物运输受阻情况的变化,即美洲商陆在低Mn刺激下会产生大量有机物作为渗透调节物质来增强其耐Mn性,高Mn则抑制了有机物的分泌和运输;根和叶组织分别在2 922和1 606 cm-1处表现不同变化趋势,但都反映了一个变化规律即低Mn处理下美洲商陆分泌的有机酸不断螯合Mn,随着Mn毒害的加重,其羧酸螯合力变弱;根组织1 732和1 026 cm-1、茎组织1 028 cm-1、叶组织1 052和967 cm-1处呈现差异性变化,但都与其膜脂过氧化有关;根组织1 375 cm-1处峰高先上升后下降,可能与植物在细胞壁结构上增强抗逆性有一定关系,即低Mn处理下细胞壁可能通过阳离子交换能力(CEC)的提高增强了耐Mn性。以上说明,利用FTIR研究重金属超积累植物化学组分具有应用价值。     

二氧化锰纳米束超级电容器电极材料制备及分析

由聚苯胺捆绑二氧化锰纳米束作为超级电容器的电极材料,具有良好的赝电容特性。聚苯胺良好的导电性影响二氧化锰纳米束的电化学性能,使其阻抗变小,稳定性增强。     

Organic Syntheses Without Solvent: Preparation of Alkoxyphthalimides and of Alkoxylamines

Alkoxyphthalimides are prepared by alkylation of N-hydroxyphthalimide under solid-liquid phase transfer catalysis without solvent. When conversion of alkoxyphthalimides into alkoxylamines is nearly complete, neat hydrazine hydrate is added at room temperature.     

Determination of trans,trans‐muconic acid in workers' urine through ultra‐performance liquid chromatography coupled to tandem mass spectrometry

A novel method for the biological monitoring of benzene‐exposed workers has been developed through ultra‐performance liquid chromatography coupled to tandem mass spectrometry. The method uses trans,trans‐muconic acid in urine as the benzene‐exposure biomarker. The method was developed using a triple quadrupole mass spectrometer with enough sensitivity to facilitate diluting and injecting the urine samples directly, rather than performing a solid‐phase extraction procedure as is common in the available protocols. Moreover, compared with a conventional high‐pressure liquid chromatography system, the separation power provided by the ultra‐performance liquid chromatography system allows a 10‐fold reduction in run time. The method was adjusted to a dynamic range of between 198.9 and 4916.7 µg/L to cover the biological exposure index of trans,trans‐muconic acid in urine. Also, the method demonstrated intra‐day and inter‐day precision at 98%, and accuracy within an acceptable range of 101 ± 8%. The method has been used to quantify various types of urine samples, such as workers' urine and inter‐laboratory proficiency tests. Depending on the sample, the quantified levels ranged from less than the limit of quantitation to 3836.7 µg/L. No levels exceeding the calibration range were detected in the urine of workers, and the reported concentrations in urine for the proficiency tests were, as expected, based on known values. Moreover, the new method using sample dilution and faster chromatographic run was more effective, facilitating fast communication of results, as needed, to decision‐makers. Copyright © 2012 John Wiley & Sons, Ltd.     

Syntheses and structures of M–Na (M=Zn,Mn) coordination polymers in which ligands and Na ions exhibit complex coordination modes

The novel heteronuclear complexes [Na₂Zn(dipic)₂(H₂O)] _n (1) and [Na₂Mn(dipic)₂(H₂O)₂] _n (2) (H₂dipic?=?pyridine-2,6-dicarboxylic acid) were synthesized and characterized by single-crystal X-ray diffraction, analysis, IR spectroscopy and thermogravimetric analysis. Complex 1 consists of infinite 2D double layers, which are further attached into a 3D network through π–π stacking. All sodium ions are 3-coordinate. Complex 2 has an intricate 3D structure, in which two sodium ions are differently involved in forming polymeric coordination units, and are 3- and 7-coordinate, respectively. Dipic anions act as multidentate ligands showing novel and unprecedented bridging coordination modes. One ligand coordinates to three metal ions and with five bonds; the other coordinates five metal ions with nine bonds.     

On the Effects of UV Radiation on the Release Ability of Glucose Embedded in Hydroxypropyl Cellulose Films

New drug delivery systems based on hydroxypropyl cellulose (HPC) and different percents of glucose were prepared and characterized to check their suitability as UV resistant patches. The spectral absorption properties of the HPC and HPC-glucose blends before and after UV irradiation were analyzed. The surface polarity and hydrophilicity were correlated with the morphology of the films and analyzed with respect to the UV exposure time and the embedded amount of glucose. The effects of UV radiation on in vitro evaluation of glucose release from the HPC films are reported. The mechanism involved in the drug release process, evaluated using the Korsmeyer-Peppas equation, was dependent on the introduced amount of glucose and less on the UV exposure time. A more polar, smoother, and less dense surface releases the glucose over larger periods of time, making the system with lower percents of glucose more adequate for the pursued purpose.     

Co-crystallizing coordination compounds

Crystallization of an equimolar mixture of 1,10-dimethylphenanthroline (DMP) and manganese(II) chloride from N,N-dimethylformamide (DMF) has been studied. Rather than a useful route to a well-defined product, it was found that identical solutions could deposit crystals of three different compounds. The most common outcome was the formation of crystals of [MnCl₂(dmp)(dmf)], 1, or co-crystallization of [MnCl₂(dmp)(dmf)] and [{MnCl₂(dmp)}₂]. The co-crystals, 2, were always found to dissolve as crystals of 1 started to grow. Crystals of a third compound, [MnCl₂(dmp)₂], 3, were also isolated once.     

Influence of Fe-doping on the microstructure and electromagnetic performance of manganese oxides

A simple wet chemical method was used to synthesize Fe-doped MnO₂ composites with iron amount ranging from 0 to 90 M percent. X-ray diffraction, electron probe micro-analyzer, scanning electron microscopy and vector network analyzer were employed to investigate the effect of iron doping on the microstructure and electromagnetic performance of the as-synthesized samples. Results indicate that relative small content of Fe-doping cannot change the α-MnO₂ structure but can promote the formation of hollow-structural morphology. The as-obtained products are transformed into a novel compound (Fe_0.67Mn_0.33)OOH with the increase of Fe-doping to 30 mol%. The possible formation mechanism was proposed in detail. Compared with the pure MnO₂, the Fe-doped samples exhibit decreased dielectric loss but increased magnetic loss with increasing the iron content below 20 mol% while relatively poor electromagnetic properties with the iron content above 30 mol%.