差示扫描量热法测定草酸艾司西酞普兰纯度

采用差示扫描量热法(DSC),根据DSC曲线利用纯度分析软件测定草酸艾司西酞普兰的纯度。对实验条件进行了优化,升温速率为4.0 K/min,称样量为2~3.2 mg。测得草酸艾司西酞普兰的纯度为99.17%,相对标准偏差为0.05%(n=6)。该法测定结果与非水滴定法测定结果(99.24%)基本一致。差示扫描量热法可用于测定草酸艾司西酞普兰纯度,方法操作简便、结果准确。     

Peak purity assessment in a triple‐active fixed‐dose combination drug product related substances method using a commercial two‐dimensional liquid chromatography system

Pharmaceutical formulations containing multiple active components challenge the development of analytical methods, especially as the individual active ingredients diverge in their physicochemical properties. Establishing specificity, especially peak purity, is one of the major evaluation criteria when developing a related substances method for drug substances or products. Fixed‐dose combination products may not be amenable to common strategies for assessing peak purity, such as performing orthogonal separations, due to the complexity of the separation and/or diversity of the active ingredients. An alternate approach to evaluating peak purity is demonstrated for a triple‐active component fixed‐dose combination product under development. A commercially available automated two‐dimensional liquid chromatography system was used to perform a selective comprehensive multidimensional separation of an active ingredient peak. The first dimension performed the drug product impurity/degradant profiling method; the second dimension assayed these fractions using the drug substance profiling method, which was pseudo‐orthogonal to the first dimension. A total of 14 targeted fractions were sampled across the first dimension main peak, with 11 containing detectable analytes and the remaining fractions bracketing the main peak. This degree of sampling allowed profiling of a coeluting degradant present at a 0.2% w/w level throughout the main peak.     

A Fmoc-based submonomeric strategy for the solid phase synthesis of optically pure chiral PNAs

A new submonomeric approach for the Fmoc solid phase synthesis of chiral PNAs is reported here. The design and synthesis of a new d-lysine-based Fmoc submonomer obtained by replacing the nucleobase residue with an Alloc group, compatible with Fmoc chemistry, is described starting from d-lysine and Fmoc-aminoacetaldehyde. The desired submonomer was obtained in high yield with no racemization. The conditions for synthesizing a chiral PNA dimer on solid support by a submonomeric approach have been optimized, allowing to obtain the desired PNA with a very high optical purity.     

氢化物发生-原子荧光光谱法测定高纯锌中痕量铋

在标准中加入锌基体,以硫脲-抗坏血酸-盐酸羟胺混合溶液为预还原剂,硼氢化钾-盐酸还原体系,采用氢化物发生-原子荧光光谱测定高纯锌中痕量铋.方法加标回收率为98.5%～105.0%,相对标准偏差为3.9%.方法适用于高纯锌中质量分数为2.0×10-5～1.0×10-2%铋的测定.     

Simple HPLC method for detection of trace ephedrine and pseudoephedrine in high-purity methamphetamine

A simple and sensitive HPLC technique was developed for the qualitative determination of ephedrine and pseudoephedrine (ephedrines), used as precursors of clandestine d‐methamphetamine hydrochloride of high purity. Good separation of ephedrines from bulk d‐methamphetamine was achieved, without any extraction or derivatization procedure on a CAPCELLPACK C₁₈ MGII (250 × 4.6 mm) column. The mobile phase consisted of 50 mM KH₂PO₄–acetonitrile (94:6 v/v %) using an isocratic pump system within 20 min for detecting two analytes. One run took about 50 min as it was necessary to wash out overloaded methamphetamine for column conditioning. The analytes were detected by UV absorbance measurement at 210 nm. A sample (20 mg) was simply dissolved in 1 mL of water, and a 50 μL aliquot of the solution was injected into the HPLC. The detection limits for ephedrine and pseudoephedrine in bulk d‐methamphetamine were as low as 3 ppm each. This analytical separation technique made it possible to detect ephedrine and/or pseudoephedrine in seven samples of high‐purity d‐methamphetamine hydrochloride seized in Japan. The presence of trace ephedrines in illicit methamphetamine may strongly indicate a synthetic route via ephedrine in methamphetamine profiling. This method is simple and sensitive, requiring only commonly available equipment, and should be useful for high‐purity methamphetamine profiling. Copyright © 2011 John Wiley & Sons, Ltd.     

Hydride Generation Atomic Fluorescence Spectrometric Determination of Ultratrace Arsenic in High Purity Indium Oxide

A simple, sensitive, and interference free method was proposed for the determination of total arsenic in high purity indium oxide by hydride generation atomic fluorescence spectrometry (HG-AFS). Preconcentration was carried out by distillation of volatile arsenic trichloride. Hydrazine sulfate was used as a prereductant to reduce As (V) to As (III). The volatile arsenic trichloride generation was based on the reaction between As (III) and hydrochloric acid, and vapors were absorbed with water. The method provides a linear response range of 2 ng/mL–70 ng/mL, a detection limit of 0.1 ng/mL, a recovery of 96%–113%, and an average relative standard deviation of 2.42%. The method was validated by means of interlaboratory comparative analysis with the proposed method HG-AFS, and the comparison of data by using proposed method HG-AFS and reference methods of ICP-OES and spectrophotometry.     

Recovery of silicon from silica fume

Feasibility of producing high purity silicon from amorphous silica fume, using a low temperature magnesiothermic reduction was demonstrated. Commercial silica fume containing 97.5% amorphous silica was first purified by acid leaching and roasting to remove large quantities of transition metals and carbon. The product was then reduced using magnesium as the reductant. The effect of the amount of reductant, initial temperature, and dwell time were investigated on the quantity and type of the reaction products. The optimum reduction conditions were decided based on the maximum yield of the Si metal. These corresponded to Mg/SiO₂ molar ratio of 2.0, preheating temperature of 750 °C, and holding time of 2 h. High purity silicon (> 99 wt.%) containing < 3 ppmw B and 12 ppmw P was obtained after leaching purification of the reduction products, showing that the material is superior to metallurgical grade silicon, for use as solar-grade silicon feedstock.     

A program for the visualisation, extraction, and reporting of NMR data from plate chemistry samples

We describe a program for the viewing, analysis, and reporting of 1D NMR spectra. The program provides an intuitive environment to display 1D NMR spectra, and assists with data reduction and reporting. It is particularly well suited for multiple NMR spectra derived from the recording of spectra of samples in microtitre plates, where it adopts a unique, effective, and user-friendly approach. This also allows for quick overviews of the underlying NMR data and offers an effective tool for quality control in parallel chemistry.     

利用光学微腔效应调节顶发射蓝光器件的色纯度

有机电致发光器件的发光颜色与色纯度在很大程度上受材料本身的限制,而通过光学微腔效应可以从器件结构上的改变来调节色纯度。本文介绍了一种通过调节有机层厚度,从而获得高纯度单色发光器件的方法。利用这种方法制作了有机顶发射蓝光器件,器件结构为Ag/m-MTDATA/NPB/DPVBi/Alq₃/LiF/Al/Ag)。通过调节有机层的厚度,获得了高色纯度的发光器件,正向出射的蓝光色坐标达到了(0.14,0.07)。     

碳化硅单晶生长用高纯碳化硅粉体的研究进展

碳化硅(SiC)以其宽带隙、高临界击穿场强、高热导率、高载流子饱和迁移率等优点,被认为是目前较具发展前景的半导体材料之一。近年来,物理气相传输(PVT)法在制备大尺寸、高质量SiC单晶衬底方面取得了重大突破,进一步推动了SiC在高压、高频、高温电子器件领域的应用。SiC粉体是PVT法生长SiC单晶的原料,其纯度会直接影响SiC单晶的杂质含量,从而影响SiC单晶的电学性质,其中生长高质量的半绝缘SiC单晶更是直接受限于SiC粉体中N元素的含量。因此,合成高纯的SiC粉体是PVT法生长高质量SiC单晶的关键。本文主要介绍了高纯SiC粉体的合成方法及研究现状,重点对气相法和固相法合成高纯SiC粉体的优缺点进行了评述,并提出了今后高纯SiC粉体合成的发展方向。