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81.
Danielle Giron S. Monnier M. Mutz P. Piechon T. Buser F. Stowasser K. Schulze M. Bellus 《Journal of Thermal Analysis and Calorimetry》2007,89(3):729-743
Adequate very sensitive quantification methods are needed for the development and are also now required for the monitoring
of undesirable solid form(s) as routine tests. The pre-requisite for quantitation are selectivity, sensitivity and most important
the purity of standards and their proper storage, what is a challenge for metastable forms.
Several analytical techniques are available such as X-ray diffraction, spectroscopy, thermal analysis and microcalorimetry.
The different steps of the validation of the analytical methods and problems to be solved are discussed. Examples illustrate
the different techniques and compare their possible advantages and limits. The relative standard deviation of measurements
should allow for checking the homogenization procedure of mixtures for calibration. The validation should be carried out following
ICH guidelines for validation of analytical methods. Comparison of different techniques in adequate concentration range add
confidence in the analytical results. 相似文献
82.
固定pH滴定法测定弱酸弱碱性药物 总被引:8,自引:0,他引:8
报道一种水溶液吕测定弱酸弱碱性药物的新型滴定分析方法-固定pH滴定法,其理论基础是弱酸弱碱在水溶液中各种存在形式的分布系数在pH值固定时为常数,对甲硝唑,盐酸美西律等离散常数在10^-8至10^-11范围内的7种弱酸弱碱性药物进行测定。结果与药典法吻合,回收率在99.4%~100.6%,方法简便,快速,准确,制剂中的赋形剂及色物不影响测定。 相似文献
83.
84.
Fisher KA Huddersman KD Taylor MJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(23):5873-5878
The uptake of the three species of the drug model fluorescein (fluorescein sodium salt (FNa), fluorescein free acid (F), and fluorescein diacetate (FDA)) by zeolite NaX and the mesoporous zeotype MCM-41 was investigated as well as their release rates into solutions at pH 7 and pH 4.5. UV/Vis analysis was carried out at a wavelength of 490 nm. Uptakes of the sodium salt of 9 % for zeolite X and 14 % for MCM suggest little penetration of the pores. The use of ethanol as the loading solvent for F resulted in little uptake for both zeolitic materials due to the successful competition of the ethanol for binding sites. Use of acetone (weaker proton acceptor) as loading solvent significantly improved the uptake of F to 17 % and 12 % for zeolite X and MCM, respectively, whilst the uptake of FDA in acetone increased still further to 22 % and 17 % for zeolite X and MCM, respectively. Generally there was a large initial release of the fluorescein analogues from the surface of the zeolites with very little further increase over time. The prescence of an esterase enzyme in the release medium of FDA tripled the release from MCM to 15 % but left the release from zeolite X unaffected at 6 %. The results obtained show that uptake of fluorescein and its analogues is dependent on the loading solvent used, the amount released is influenced by not only the solvent but the pH and the presence of enzymes in the release medium. 相似文献
85.
Xiaoping Zhan 《European Polymer Journal》2007,43(4):1588-1594
Oral clonidine, used as an antihypertensive, can result in some side effects such as dry mouth, drowsiness, dizziness and sedation; thus, clonidine transdermal drug delivery (TDD) was considered. Use of the controlled release membrane was one of the methods in TDD systems to regulate the permeation properties. A new type of copolymer membrane that controlled clonidine linear release in TDD system was synthesized by UV radiation. This membrane consisted of three monomers: 2-hydroxy-3-phenoxypropylacrylate, 4-hydroxybutyl acrylate and diethyl maleate. The membrane had both fine permeation properties and perfect physical properties when three monomers were in the weight ratio of 4:4:2; this type of membrane was chosen as an optimized membrane. It was found that the membrane controlled clonidine zero-order release, the permeation rates decreased with the thicknesses of membranes increasing, and the permeation rates were linearly dependent on the square root of the concentration of clonidine. Furthermore, the optimized membranes were characterized by FTIR, DSC and SEM. 相似文献
86.
Panaxynol is a bioactive component in traditional Chinese medicines (TCMs), such as Saposhnikovia divaricata and Panax ginseng. In the work, two solvent-free sample techniques of pressurized hot water extraction (PHWE) and headspace liquid-phase microextraction (HS-LPME) were combined and developed for the determination of panaxynol in a TCM of S. divaricata. Panaxynol in the TCM samples from different growing areas was extracted by PHWE in dynamic mode, followed by extraction and concentration with HS-LPME and analysis with gas chromatography-mass spectrometry (GC-MS). The PHWE and HS-LPME parameters were optimized and the method validations were studied. Panaxynol in S. divaricata from four different growing areas was quantitatively analyzed by internal standard method. These results have shown that PHWE-LPME-GC-MS is a simple, rapid, efficient and low-cost method for the determination of panaxynol in TCMs and is a potential tool for TCM quality assessment. 相似文献
87.
用内径为0.53mm的填充毛细管正相液相色谱为第一维,用4.6mm(i.d.)×50mmRP-18e整体柱反相色谱为第二维,建立了定量环一阀切换接口的全二维液相色谱系统(NPLC×RPLC).第一维色谱分离洗脱出的组分交替存储在十通阀上的两个定量环中,同时定量环中前一个组分被转移到第二维进行反相分离.因为第一维的流动相流量仅是第二维的1/500,自然解决了流动相兼容问题.采用芳香族化合物的混合物和中药丹参正己烷提取液对该全二维液相系统的分离能力进行了评价. 相似文献
88.
四君子汤和四物汤微量元素含量研究 总被引:1,自引:0,他引:1
通过了解中药“四君子汤”和“四物汤”中微量元素含量的异同,研讨了微量元素和中医“气血”理论之间的关系。实验表明,“四君子汤”和“四物汤”在微量元素的含量方面,有一定的类同和差异。该现象同中医的“气血”理论有非常相像的地方。同时发现中药中的微量元素在煎煮过程中,并不是同想象的一样匀速进入药液,而是不同的元素在不同的时间段不同的批次进入药液,这也提示中药煎法理论有一定依据。由于目前做的实验还少,本实验留下很多问题和疑点,值得进一步做有关的实验和研究。 相似文献
89.
the interaction of hemin with chloroquine,quinine and quinidine was investigated in 50% water-propylene glycol mixture at pH=9,8.1,7.4 and 6.8using a spectrophotometric method.The data could be well fitted into a model consistent with the formation of a 1:1 complex between the reacting partners.In addition,the results indicated that hemin complexed more strongly with quinidine than with chloroquine and quinine,and the binding constants were pH-dependent.Moreover,it was proved that the water-propylene glycol mixture is well suitable to the study of the systems containing hemin and quinolinebased drugs. 相似文献
90.