新解色谱现象

在客观分析色谱现象的基础上对色谱分离机理的传统解释提出了质疑和否定,并对色谱分离机理作出了新的解释。通过对色谱现象的研究和分析,不仅确定了一条流体运动的基本规律,还对固定相赋予了新的内涵,提出了能量场固定相的设想。由于对色谱分离原理进行了新的解释,因此对色谱现象提出了一个新的定义。     

新铜试剂-铜(Ⅱ)体系萃取原子吸收法间接测定微量碘的研究

本文研究了NCP-Gu(Ⅰ)·I~-离子对的彤成和萃取条件,离子对的组成及其对测定灵敏度的影响。利用萃取分光光度法验证了离子对的组成,探讨了吸收峰的本质。测定了健康人血清和海带煮沸液中微量游离I~-,获得了满意的结果。     

纳米纤维素的制备

纳米纤维素(NCC)由于其大量、可再生、可生物降解以及优良的力学性能,成为纳米技术领域研究的热点。文章综述了NCC的制备方法,对化学和机械法制备NCC纤维素做了重点介绍,同时,对NCC的表面改性进行了综述。并对NCC在制备纳米复合材料领域的应用进行了总结,对其在增强复合材料中的应用做了较详细的介绍。最后对NCC未来的发展进行了展望。     

化学课堂教学的发展性评价指标及观测点的确定

对化学课堂教学发展性评价指标制定了操作性定义,并设计了具体观测点和测量表,拟对化学课堂教学做一个全面的、综合的发展性评价。并用该测量表对本校高二年级学生和教师做了调查,及时反馈给了教师,对本校教师的课堂教学提出了发展性的意见和建议。     

纳米微晶纤维素制备*

纳米微晶纤维素（NCC）由于其大量、可再生、可生物降解以及优良的力学性能,成为纳米技术领域研究的热点。文章综述了NCC的制备方法,并对化学和机械法制备NCC纤维素作了重点介绍。同时对NCC的表面改性进行了综述。并对NCC在制备纳米复合材料领域的应用进行了总结,对其在增强复合材料中的应用作了较详细的介绍。最后对NCC未来的发展进行了展望。     

大型机组轴系多轴激光对中方法研究

基于单半导体激光器(LD)-单位敏探测器(PSD)激光对中仪,通过加装V型架和弹性带改变对中仪与传动轴的连接方式,构建了一套无需轴系转动即可完成大型机组多轴轴系对中测量的激光对中测量系统。解决了大型轴系对中测量时因盘车困难所导致的测量过程难以进行的问题。同时建立了对中仪测量数据优化计算数学模型,利用最小二乘法拟合空间直线可对调整量进行优化。该算法优化模型经三轴系样机对中测量验证,可以满足工程轴系同轴度检测要求,并且与对中仪直接获取的对中调整量相比,优化算法可将轴系调整量降低20%以上,有效改善了大型机组多轴系对中调整过程中调整量过大的问题。该测量系统及优化算法为大型机组轴系激光对中测量提供了新的解决办法,提高了对中效率,拓宽了激光对中仪的适用范围。     

碳纳米管的纯化——电化学氧化法

用电化学氧化法碳纳米管进行纯化,从稳态极化曲线出发,对反应的可行性进行了分析,考察了支持电解质、电流密度、时间等因素对反应的,确定了最佳实验条件,同时对纯化机理进行了解释。     

合成气在 Fe/HZSM-5复合催化剂上转化制烃—沸石的特性和催化作用

对各种HZSM-5沸石的形选性和酸性作了表征,并在熔铁和HZSM-5沸石复合催化剂上考察了沸石对合成气制烃反应的催化作用。结果表明,沸石的形选性、酸性和催化作用因沸石的来源、质子化方法和水蒸汽处理条件的不同而异。沸石的存在提高了合成气转化率,产物碳数不大于11。沸石的特性差异对上述两者无显著影响,对产物选择性影响很大。讨论了不同强度的酸中心对裂化和芳构化的作用,并指出调变沸石酸性对提高目的产物选择性的重要性。对汽油馏份和沸石含碳沉积物的性质作了初步表征,并讨论了焦的成因。     

反相离子对色谱中离子对试剂浓度对保留值的影响

本文采用热力学与Gouy-chapmann理论相结合的方法, 考察了离子对试剂浓度对反相离子对色谱保留值的影响, 获得了反相离子对色谱ink'与离子对试剂浓度间的近似线性关系。同时考察了溶质疏水性和熔质电荷数对线性关系式中斜率和截距的影响。     

有机化合物的鉴定 Ⅵ.一些耐高温有机硅化合物的显微鉴定

1.合成了6种四芳基硅烷,其中4种是新化合物,即四(对-乙苯基)硅烷,四(对-异丙苯基)硅烷,四(对-叔丁苯基)硅烷及四(对-三甲基硅苯基)硅烷。2.样品经仔细纯化后,测定了准确熔点,对已知样品熔点的文献纪录作了修正。3.对合成样品作了显微摄影鉴定。     

PLS-ANN算法-NIR光谱非破坏性Norvasc药物有效成分的定量分析

采用偏最小二乘(PLS)结合人工神经网络(ANN)算法解析Norvasc(络活喜)药片的近红外(NIR)漫反射光谱, 实现了对其中有效成分苯磺酸氨氯地平的非破坏定量测定. 设计了最佳的PLS-ANN模型, 分别讨论了最佳波长范围、 导数光谱及输入层和隐含层节点数对预测结果的影响. 以HPLC法的测定结果作标准, 苯磺酸氨氯地平浓度预测值的相对误差RE＜3.5%, 该方法可用于Norvasc药品实际生产中的质量控制.     

Highly sensitive kinetic spectrophotometric method for tramadol trace level detection and process optimization using response surface methodology

Tramadol is a centrally acting analgesic‐anodyne agent of high oral bioavailability. The tramadol contains a weakly absorbing chromophore in its molecule and it was determined by kinetic spectrophotometric method in pharmaceutical, urine, and blood plasma. Response surface methodology and the central composite design was applied to study the influence of maximum sensitivity, reagents concentration, temperature, and time on the UV–Vis spectrophotometry analysis of tramadol. Analysis of variance showed a high coefficient of determination (R²) value for responses, confirming adjustment of the models with experimental data. The change in absorbance was followed spectrophotometrically at 478 nm. Under optimum experimental conditions, calibration curve was linear over the range 0.45–100.0 μg/L of tramadol. The limit of detection was 0.12 μg/L of tramadol. The developed method was successfully applied for the determination of tramadol in real samples.     

近红外光谱无损定量分析吡嗪酰胺片

近红外光谱;径向基神经网络;吡嗪酰胺;定量分析     

Influence of tabletting speed on compactibility and compressibility of two direct compressible powders under high speed compression

To examine the influence of tabletting speed on compactibility and compressibility under high speed compression, two direct compressible powders, alpha-lactose monohydrate and microcrystalline cellulose of different particle size ranges were compressed using an instrumented rotary press with varying tabletting speed and compression force. The maximum applied force and total time during compression (contact time) were determined from a time-force profile, and the relation between these parameters and properties of compacts was examined. For all lactose tablets, the porosity and tensile strength of compacts were less affected by compression rate though they depended on the applied force. However, the properties of microcrystalline cellulose tablets were varied depending on the tabletting speed in addition to the applied force. In an attempt to quantitatively evaluate the effect of compression rate on the compactibility, an empirical equation was derived from the numerical analysis of the experimental data. The compactibility parameters deduced from the equation well elucidated the effect of tabletting speed on the properties of microcrystalline cellulose tablets and lactose tablets made of various particle size powders.     

Enhanced Characterization of Naproxen Formulation by Near Infrared Spectroscopy

Near infrared spectroscopy in combination with appropriate chemometric methods is an effective technique for quantitative analysis of parameters of interest for the pharmaceutical industry. In this study, the artificial neural network (ANN) was applied to monitor critical parameters (compression force, tablet hardness, mean particle size, and active pharmaceutical ingredient concentration of tablets) in the process of naproxen pharmaceutical preparation. The performance of ANN was compared to linear methods (partial least squares regression (PLS) and synergy interval partial squares (siPLS)). The ANN models for compression force, tablet hardness, mean particle size, and active pharmaceutical ingredient concentration of tablets yielded the low root mean square error of prediction (RMSEP) values of 0.936 KN, 0.302 kg, 4.49 mg, and 2.14 µm, respectively. The predictive ability of the PLS model was improved by siPLS with selection of spectral regions and the best performance among all calibration methods was showed by the nonlinear method (ANN). Effective models were built by using these approaches using near infrared spectroscopy.     

Peculiar behavior of polysaccharide/borax hydrogel tablets: a dynamomechanical characterization

The peculiar unidirectional elongation observed during swelling of tablets prepared with scleroglucan (Sclg) and borax was compared with that of other synthetic and natural polymers capable of physical/chemical interactions with borate ions. A dynamomechanical characterization of “squared” Sclg/borax tablets was carried out to study the differences detectable on the two sides of the matrix corresponding to the two directions, respectively, the parallel and perpendicular one with respect to the applied compression force. Different compression forces were used and, in some cases, a second compression was applied on the tablets along a direction perpendicular to the first one. Birefringence experiments were carried out on the swelled tablets along the two directions. Obtained results allow correlating the anisotropic swelling behavior with the detected dynamomechanical and optical properties of the Sclg/borax system. Among the various tested polymers, only guar gum and, to a lesser extent, locust bean gum, showed an anisotropic elongation during swelling.     

Chromatographic Behavior of Fosinopril Sodium and Fosinoprilat Using Neural Networks

In this paper, the chromatographic characterization of fosinopril sodium and fosinoprilat is presented. The first stept was pK _a determination for the active substance and its degradation product using RP-LC. It was followed by optimization employing the combination of experimental design and artificial neural networks. For the definition of input and output variables, the central composite design for three factors was built. Back propagation algorithm was applied to model the system, and then the optimization of the experimental conditions was carried out in the neural network with 3-8-2 structure, which confirmed to be able to provide the maximum performance. From the method optimization, the most appropriate experimental conditions for fosinopril sodium and fosinoprilat analysis were extracted. The optimized method was validated and applied in the quality control of tablets and for forced degradation studies.     

Subcritical water extraction and determination of nifedipine in pharmaceutical formulations

A rapid and simple continuous method for the extraction of nifedipine from tablets was developed by using pressurized hot water at 150 degrees C. This is the first time that subcritical water was applied to the extraction of low-polarity compounds in pharmaceutical analysis. The method is based on the increment in solubility of nifedipine in subcritical water. Extraction temperature and static and dynamic extraction time were optimized in order to reach quantitative extraction of the drug from the tablets. After extraction, the drug was determined by spectrophotometry by measuring absorbance at 338 nm. Accuracy and precision of the method were determined by analysis of 10 synthetic samples of pharmaceutical formulations prepared with common tablet excipients. Recovery was found to be 99.2% with a relative standard deviation of 1.9%, which indicates that the excipients of the formulation do not interfere in the determination. The method was applied to the determination of the drug content uniformity in tablets.     

Capillary GC-MS determination of melatonin in several pharmaceutical tablet formulations

A simple capillary GC-MS method for the determination of melatonin from tablets is proposed. Melatonin (N-acetyl-5-methoxytryptamine) was determined by gas chromatography-mass spectrometry after extraction from ground tablets with ethyl acetate and derivatization with N-methyl-N-trimethylsilyl-heptafluorobutyramide (MTSHFBA). Splitless injection offers good reproducibility with a standard deviation of +/- 2%. The proposed method was applied to analyse the melatonin content from three different tablet formulations.     

Development and validation of a chiral capillary electrophoresis method for assay and enantiomeric purity control of pramipexole

A rapid method for the enantioseparation of pramipexole and its R‐enantiomer has been developed by capillary electrophoresis. The influence of chemical and instrumental parameters was investigated including the type and concentration of chiral selectors, buffer composition and pH, co‐ions, applied voltage, capillary length and temperature. Optimal separation conditions were obtained using a 50 mM phosphate buffer (pH 2.8) containing 25 mM carboxymethyl‐β‐cyclodextrin on a fused‐silica capillary. Online UV detection was performed at 262 nm. A voltage of 25 kV was applied, and the capillary temperature was kept at 25°C. Hydrodynamic injection was performed at 3.45 kPa for 5.0 s. The separation of enantiomers was achieved in <6.5 min. The method was further validated in terms of stability of solutions, selectivity, linearity (both pramipexole and R‐enantiomer, R²>0.995), LOD and LOQ (0.91 and 2.94 μg/mL, respectively), repeatability (RSD<1.5%) and accuracy (pramipexole, 100.4%; R‐enantiomer, 100.5%). The proposed method was then applied to two kinds of pramipexole dihydrochloride monohydrate commercially available tablets, immediate release tablets (1.50 and 0.125 mg) and sustained release tablets (0.52 mg), to quantify the main component in the tablets. The amount of distomer could be quantified in bulk sample materials.