等温平台石墨炉原子吸收光谱法测定高纯铟中痕量杂质镉和锑

石墨炉原子吸收法在等温平台条件下 ,利用标准加入法直接测定了高纯铟中的痕量杂质镉和锑。对石墨炉加热程序中的干燥时间、灰化温度及原子化温度进行了优化 ,考察了介质酸度的影响。在测定锑时 ,加入了基体改进剂钯。镉和锑的特征质量分别为 3.2 pg和 77.1 pg,相对标准偏差平均值分别为 1 .9%和 3.1 % ,加标回收率分别为 86 %— 92 %和 81 %— 91 %。     

基于高光谱图像技术的玉米杂交种纯度鉴定方法探索

对玉米种子高光谱图像的光谱维信息进行分析,探索利用高光谱图像技术鉴定玉米杂交种纯度的可行性。实验中利用高光谱成像系统采集玉米品种农华101的母本和杂交种的高光谱图像, 波长范围871～1699 nm;在每个玉米样本上提取感兴趣区域的平均光谱信息,利用处理后的数据建立农华101母本和杂交种的鉴定模型。讨论了样品的摆放方式(种子胚正对光源和背对光源,种子在样品台上的位置)和实验环境对鉴定模型性能的影响。鉴定模型对不同摆放方式和实验环境下获得的同种样品的光谱的正确识别率和正确拒识率均达到90%以上,模型稳健性良好。利用Qs方法选择特征波段[1],发现在1 230 nm附近(1 195～1 246 nm)农华101的母本和杂交种差异最大。实验中利用特征波段内的数据进行建模和测试,正确识别率和正确拒识率达到90%以上,与利用全波段(925～1597 nm)获得的识别效果相当。分析结果表明,利用高光谱图像技术鉴定玉米杂交种纯度是可行的。     

基于主动学习的玉米种子纯度检测模型更新

种子纯度反映种子品种在特征特性方面典型一致的程度,提高种子纯度检测的准确性和可靠性对保证种子的质量具有重要的意义。高光谱图像技术可以同时反映种子的内部特征和外部特征,在农产品无损检测中已经得到广泛应用。利用近红外高光谱图像实现农产品无损检测的实质就是建立光谱信息与农产品品质参数之间的数学模型关系。但光谱信息易受环境、时间的影响,当待测样本的产地或者年份发生改变时光谱信息也随之改变,导致建立的模型的稳定性变差、泛化能力减弱。针对这一问题,采用主动学习算法选择具有代表性的待测样本,最终以添加最少最优的样本数来扩大原模型的样本空间,从而实现模型的快速更新,提高模型的稳定性,同时与基于随机选择算法（RS）和Kennard-Stone算法(KS)的模型更新效果进行比较。实验结果表明：在不同样本集划分比例下（1∶1, 3∶1, 4∶1）,利用主动学习添加40个新样本更新后的2010年的玉米种子纯度检测模型对2011年新样本的预测精度由47%,33.75%,49%提高到98.89%,98.33%,98.33%;利用主动学习添加56个新样本更新后的2011年的玉米种子纯度检测模型对2010年新样本的预测精度由50.83%,54.58%,53.75%提高到94.57%,94.02%,94.57%;同时基于主动学习算法的模型更新效果明显优于RS和KS。因此基于主动学习算法实现玉米种子纯度检测模型的更新是可行的。     

Pressure-Tuned Multicolor Emission of 2D Lead Halide Perovskites with Ultrahigh Color Purity

The chemical diversity and structural flexibility of lead halide perovskites (LHPs) offer tremendous opportunities to tune their optical properties through internal molecular engineering and external stimuli. Herein, we report the wide-range and ultrapure photoluminescence emissions in a family of homologous 2D LHPs, [MeOPEA]₂PbBr_4−4xI_4x (MeOPEA=4-methoxyphenethylammonium; x=0, 0.2, 0.425, 0.575, 1) enabled through internal chemical pressure and external hydrostatic pressure. The chemical pressure, induced by the C−H⋅⋅⋅π interactions and halogen doping/substitution strengthens the structural rigidity to give sustained narrow emissions, and regulates the emission energy, respectively. Further manipulation of physical pressure leads to wide-range emission tuning from 412 to 647 nm in a continuous and reversible manner. This work could open up new pathways for developing 2D LHP emitters with ultra-wide color gamut and high color purity which are highly useful for pressure sensing.     

Purity assessment of recombinant human granulocyte colony‐stimulating factor in finished drug product by capillary zone electrophoresis

Current methods for determination of impurities with different charge‐to‐volume ratio are limited especially in terms of sensitivity and precision. The main goal of this research was to establish a quantitative method for determination of impurities with charges differing from that of recombinant human granulocyte colony‐stimulating factor (rhG‐CSF, filgrastim) with superior precision and sensitivity compared to existing methods. A CZE method has been developed, optimized, and validated for a purity assessment of filgrastim in liquid pharmaceutical formulations. Optimal separation of filgrastim from the related impurities with different charges was achieved on a 50 μm id fused‐silica capillary of a total length of 80.5 cm. A BGE that contains 100 mM phosphoric acid adjusted to pH 7.0 with triethanolamine was used. The applied voltage was 20 kV while the temperature was maintained at 25°C. UV detection was set to 200 nm. Method was validated in terms of selectivity/specificity, linearity, precision, LOD, LOQ, stability, and robustness. Linearity was observed in the concentration range of 6–600 μg/mL and the LOQ was determined to be 0.3% relative to the concentration of filgrastim of 0.6 mg/mL. Other validation parameters were also found to be acceptable; thus the method was successfully applied for a quantitative purity assessment of filgrastim in a finished drug product.     

NH-1分离5''-核苷酸的研究

针对4种5’-核苷酸(AMP、GMP、CMP和LIMP)的理化特性，合成了一种新的阳离子交换树脂NH-1．研究了4种5’-核苷酸在NH-1树脂上的分离度，优化了工艺条件．实验结果发现：当上柱液pH为2．2、上柱量0．02g／ml-resin，上柱及洗脱线速度0．5m／h，高径比15：l时，4种物质间的分离度均大于10，分离总收率大于93％，UMP的纯度为80％左右，其余3种纯度均在95％以上．     

1 H NMR Spectral Simplification with Achiral and Chiral Lanthanide Shift Reagents. Clenbuterol. Method for Direct Optical Purity Determination

The 60 MHz ¹H NMR spectra of clenbuterol, 1, have been studied in CDCl₃ solution with the achiral shift reagent, tris (6,6,7,7,8,8,8-hepta-fluoro-2,2-dimethyl-3,5-octanedionato)europium (III), 2, and the chiral reagent tris[3-(heptafluoropropylhydroxyn1ethyl-ene)-(+)-canphorato]europiunr(III), 3. Use of 3 resulted in observable enantiomeric shift differences, ΔΔσ, for the t-butyl, NH₂ benzylic CH and the aryl proton signals. Values of ΔΔσ as high as 135.1 Hz (2.25 ppm) and 86.5 Hz (1.44 ppn) were seen for the methine and aryl protons, respectively, with a solution 0.1035 molal in 1 and a 1:3 molar ratio of 0.551. The aryl resonance is especially well suited for direct optical purity determinations of 1.     

1H NMR Spectral Simplification with Chiral Solvating Agents and with Achiral and Chiral Lanthanide Shift Reagents. Cis-4,5-Dihydro-4-Methyl-5-Phenyl-2-Oxazolamine, “Cis-4-Methylaminorex,” a Potent Stimulant and Anorectic

Abstract

The 60 MHz ¹H NMR spectra of racemic (+)-cis-4,5-dihydro-4-methyl-5-phenyl-2-oxazolamine, 1, have been studied at 28° in CDC1₃, solution with the achiral lanthanide shift reagent (LSR), tris(6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionato) europium(III), 2, and the chiral reagent tris[3?(heptafluoropropylhydroxymethy1ene)-d-camphor-ato]europium(III), 3. Additional NMR studies were performed at 400 MHz in CDC1, solution at 24° using the chiral solvating agents (CSA), (E)-(-)-2,2,2-trifluoro-1- (9-anthryl) ethanol, 4, and (R) - (+) -α-methoxy- α-(trifluoromethy1)phenylacetic acid, 5. Substantial enantiomeric shift differences, for the CH₃, signal of 1 using 3 or 5, and for the ortho aryl protons using4, which should make possible direct optical purity determinations of 1. Accurate 400 MHz data f o r chemical shifts and vicinal coupling constants of, of racemic cis-1 are presented, and compared with values for (optically active) (-)-trans-1; some dfferences are seen compared to previously reported data. solution. The LSR and CSA results are compared and Some additional data were obtained in C₆D₆ discussed.     

Purity assessment problem in quantitative NMR—impurity resonance overlaps with monitor signal multiplets from stereoisomers

This paper describes the situation that can emerge when the signals to be evaluated in quantitative NMR measurements—so-called “monitor signals”—consist of several resonance lines from the stereoisomers of the analyte in addition to an impurity signal underneath. The monitor signal problem is demonstrated in the purity assessment of two samples of 2-(isopropylamino)-4-(ethylamino)-6-chloro-1,3,5-triazine (atrazine), a common herbizide which served as analyte in a CCQM intercomparison. It is shown that, in DMSO-d₆ solution, a mixture of stereoisomers leads to several individual overlapping singlets, which are further split by spin–spin coupling. A measurement protocol was developed for finding and identifying an impurity that has a signal that is positioned precisely beneath the methyl signal chosen as the monitor signal in one of the samples. Quantitative NMR purity assessment is still possible in this special case, but with higher uncertainty. Electronic Supplementary Material Supplementary material is available for this article at     

Characterization and Purity Determination of Trans (±) 1,2-Diaminocyclohexane Platinum (Iv) Tetrachloride Using Liquid Chromatography With A Platinum Selective Detector

Abstract

An important aspect of drug development is the reliable determination of the purity of a bulk drug substance. In the case of Trans (±) 1,2-Diaminocvclohexane Platinum (IV) Tetrachloride, classical techniques such as differential scanning calorimetry and phase solubility analysis cannot be used because of the compound's poor tabulation of the fractions (percent) of platinum contained in each peak as measured with d.c. plasma and a corresponding response factor for the UV detector. the power of the d.c. plasma detector in producing unequivocal information on the platinum-containing species and its application in elucidating the data obtained with the UV detector is well demonstrated in this case.