A Fast and Simple Screening Method for m-Nisoldipine and Its Related Substances by MEKC

A rapid and simple method has been developed and validated for the determination of m-nisoldipine and its five related substances using micellar electrokinetic capillary chromatography (MEKC). The key factors, including pH, buffer concentration and buffer additive, sodium dodecyl sulfate (SDS) concentration, applied voltage and temperature were systematically investigated in an uncoated fused silica capillary. The total analysis time was less than 9 min. The forced degradation products of m-nisoldipine, which were induced by hydrogen peroxide, acidic and basic conditions, heat and light, were also tested.     

A Fast and Simple Screening Method for m-Nisoldipine and Its Related Substances by MEKC

A rapid and simple method has been developed and validated for the determination of m-nisoldipine and its five related substances using micellar electrokinetic capillary chromatography (MEKC). The key factors, including pH, buffer concentration and buffer additive, sodium dodecyl sulfate (SDS) concentration, applied voltage and temperature were systematically investigated in an uncoated fused silica capillary. The total analysis time was less than 9 min. The forced degradation products of m-nisoldipine, which were induced by hydrogen peroxide, acidic and basic conditions, heat and light, were also tested.

     

Separation of Structurally Related Anthocyanins by MEKC

Summary A method based on micellar electrokinetic chromatography has been developed for the simultaneous separation of six anthocyanins (malvidin-3,5-diglucoside, malvidin-3-glucoside, malvidin-3-galactoside, pelargonidin-3-glucoside, cyanidin-3,5-diglucoside, cyanidin-3-galactoside). Optimum selectivity was achieved in the buffer 30 mM phosphate + 400 mM borate-TRIS, pH=7.0 supported with 50 mM sodium dodecylsulphate. High content of borate was essential mainly for the separation of diastereomeric pair malvidin-3-glucoside-malvidin-3-galactoside. The calibration dependencies exhibit good linearity in the ranges of concentration 10–100 g mL^–1 for diglycosylated and 25–100 g mL^–1 for monoglycosylated derivatives (R² = 0.9711–0.9989). The optimized method was applied to a sample of wine grape skin extract. Malvidin-3-glucoside was identified as main anthocyanin colorant in this sample.     

Analysis of Zoledronic Acid and Its Related Substances by Ion-Pair RP-LC

A simple high-performance liquid chromatographic method – ion-pair reversed- phase high performance liquid chromatography (RPIC) has been developed and employed for the analysis of zoledronic acid and its related substances in bulk material and commercial dosage forms. The mobile phase was a mixture of methanol (20%) and 5 mmol L^–1 phosphate buffer (80%) containing 6 mmol L^–1 tetrabutylammonium bromide, adjusted to pH 7.0 with sodium hydroxide. C₈ column was used as the stationary phase. The chromatographic conditions were optimized. The active ingredient – zoledronic acid was successfully separated from its related substances, including remained imidazol-1-yiacetic acid in the synthesis of zoledronic acid and other possible impurities of oxidation and decomposition. The excipients did not interfere with the determination of zoledronic acid in commercial dosage formulations. The method was rapid, simple, accurate and reproducible. It was not only successfully employed for the assay of zoledronic acid in bulk material and pharmaceutical dosage forms but also for the determination of its related substances.     

Fast Analysis of Statins in Pharmaceuticals by MEKC

A universal micellar electrokinetic capillary chromatographic (MEKC) method with diode-array detection for the simultaneous and short-time analysis of lovastatin, simvastatin, pravastatin, fluvastatin, atorvastatin and rosuvastatin was introduced. Base hydrolysis was used to open lactone ring of lovastatin and simvastatin, administered as lactone prodrugs, in order to transform these compounds to the corresponding β-hydroxyl acid forms before MEKC analysis. This approach offered shorter analysis time due to a decrease of the migration times of negatively charged statin drugs in comparison to neutral lactone forms. Optimized conditions were found to be a 25 mM borate buffer pH 9.5 with 25 mM sodium dodecyl sulphate and 10% methanol added as an organic modifier, an applied voltage of 23 kV and a separation temperature of 30 °C. Ketoprofen was used as an internal standard. The linearity of the detector response for each statin was within the concentration range from 10 to 100 μg mL^?1 with a correlation coefficient greater than 0.9994. Analyses of six statin drugs in pharmaceutical samples were carried out in only 5 min. The interference of the tablet sample matrix was not observed. The recovery values were in the range of 98.04–100.80%.     

Synthesis of Zolmitriptan and Related Substances

Efficient and cost-effective synthesis of Zolmitriptan 1 employing Japp–Klingemann reaction and a new robust purification strategy is described.     

熊去氧胆酸生产中相关物质的分析

建立了HPLC-示差折光检测器外标法测定熊去氧胆酸中4种特殊杂质及其他有关物质含量的方法,结果表明各样品在测定范围内线性关系良好(r=0.999 1~0.999 6),方法回收率、精密度、稳定性、重复性均符合要求,适用于熊去氧胆酸生产的质量控制。     

红霉素肟及相关化合物的高效液相色谱分析

探讨和优化红霉素肟及相关化合物的HPLC分析色谱条件 ,紫外检测波长为 2 0 5nm ,使用Hitachi色谱系统 ,ODS C1 8色谱柱 (1 5 0mm× 4mmI.D .) ,控制流速 1mL min ,流动相为磷酸二氢钾 乙腈 (65∶3 5 ) ,明确指认了红霉素肟合成中主要成分的Z、E异构体 ,红霉素 6,9 半缩酮 ,红霉素 6,9 9,1 2螺缩酮的位置 ,同时对红霉素A ,红霉素C的吸收峰位置也进行了辨析 ,线性相关性良好。对红霉素肟及相关化合物的详细HPLC解析 ,为有效改进红霉素肟的合成工艺起到指导作用     

On-Line Concentration Methods for Analysis of Fat-Soluble Vitamins by MEKC

A fast, selective and sensitive reversed phase liquid chromatographic method employing a C-18 column has been developed and validated for simultaneous analysis of four impurities of duloxetine hydrochloride, an antidepressant drug, viz., (S)-N,N-dimethyl-3-hydroxy-(2-thienyl)-propanamine, phenolic impurity, 1-napthol and duloxetine succinamide. Good separations were achieved by a gradient elution with mobile phase consisting of a mixture of phosphate buffer 14 mM containing 0.1% of sodium octanesulfonate, pH 3.0, at a flow rate of 0.8 mL min^?1. The detection was at 220 nm. The method was validated for precision, linearity and accuracy. Finally, the developed method was used to quantify the impurities during stability sample analysis of duloxetine hydrochloride drug products.     

Comparison of Three RP-HPLC Methods for Analysis of Cefpodoxime Proxetil and Related Substances

A comparison of testing methods for analysis of cefpodoxime proxetil and its related substances was performed to determine which available analytical method was most appropriate for quality control. Three RP-HPLC methods are reviewed. They are adopted by Requirements for Antibiotic Products of Japan 1998 (Method 1), the United States Pharmacopoeia 28th (Method 2) and a method provided by a manufacture company (Method 3). Methods were compared in terms of specificity, stability of sample solution, sensitivity, precision, and robustness. Method 1 consisted only of water and methanol, eliminating possible degradations observed in phosphate and acetate buffers, and allowed baseline separation of cefpodoxime proxetil from its known related substances, including stereo and structural isomers, possible degradation compounds and by-products within 40 min, demonstrating more specificity and efficiency than Method 2. However, cefpodoxime proxetil dimer (open) could not be eluted within 60 min with Method 1. Method 3 gave partly similar results to those of Method 1 and also allowed the detection of cefpodoxime proxetil dimer (open). Results showed that Method 1 and Method 2 had some limitations for the impurity control. For chromatographic impurity control, Method 3 is the best choice.     

Establishment and Optimization of an HPTLC Method for the Analysis of Gatifloxacin and Related Substances by Design of Experiment

JPC – Journal of Planar Chromatography – Modern TLC - The objective of this study was to establish and optimize high-performance thin-layer chromatography (HPTLC) analysis of...     

阿德福韦酯及其有关物质的胶束电动毛细管色谱法快速测定

采用胶束电动毛细管色谱法对阿德福韦酯及其有关物质进行了快速分离与测定,并对电泳条件进行了优化.在优化条件下,阿德福韦酯及其有关物质在12 min内得到良好的分离,阿德福韦与阿德福韦酯在质量浓度分别为6.28×10-2～4.02 g·L-1与6.19×10-2～3.96 g·L-1的范围内与峰面积呈良好的线性关系,加标回收率分别为100%～101%和98%～101%,检出限分别为0.3、0.5 mg·L-1.该方法简单、快速,适用于阿德福韦酯及其有关物质的常规检查和该药的质量控制.     

反相高效液相色谱法测定盐酸齐拉西酮及有关物质

建立了盐酸齐拉西酮及有关物质的反相高效液相色谱测定法。采用C18色谱柱,以甲醇-50mmol／L醋酸钠缓冲溶液梯度洗脱,使盐酸齐拉西酮及8个中间体基线分离,采用二极管阵列检测器,检测波长254砌。各杂质的最低检出限均可满足测定的要求。建立的方法操作简便,重现性好,结果准确。     

金刚烷胺标准品中纯度受限的杂质分析

为确定购买的金刚烷胺标准品中使纯度受限的主要杂质成分,用质量平衡法对标准品中主成分含量进行定值分析。采用红外光谱、质谱等方法对金刚烷胺标准品的主成分进行定性,用气相色谱–质谱法、顶空气相色谱法、卡尔费休法对其主要杂质进行确证并定量。结果表明金刚烷胺标准品中主要杂质成分为溴代金刚烷胺、甲醇、乙苯和水,含量分别为1.53%,0.0376%,0.0045%,0.41%,经计算金刚烷胺标准品的纯度为98.16%。该方法可用于金刚烷胺标准品主要杂质的定性、定量分析,对其纯度值进行验证。     

“物质的量”概念的探讨及其有关计算方法之我见

物质的量是物理化学和分子物理学这门学科范围的基本量。长期以来,人们习惯用当量,当量浓度及摩尔浓度等现已废弃的单位去计算。而当前国际单位制(SI)以物质的量作为基本量。为了使大家对物质的量能正确的理解和使用,本文特对其概念进行了讨论,并提出了与之适应的计算方法。     

全氟和多氟化合物环境问题研究

全氟和多氟化合物（PFASs）是一类具有重要应用价值的含氟有机化合物,许多全氟和多氟化合物难以光解、水解和被生物降解,因此具有环境持久性,并可沿食物链累积放大。2009年5月9日,全氟辛烷磺酸（PFOS）及其盐和全氟辛烷磺酰氟被正式列入持久性有机污染物（POPs）名单,由此全氟和多氟化合物成为近年最受关注的新型污染物,其环境问题研究进入到了新的广度和深度。本文将就其分析方法、环境存在、生物累积放大效应、人体暴露和健康效应、新型全氟和多氟化合物等方面的研究,特别是2009年PFOS等被纳入POPs公约以来取得的研究新进展,进行较为全面的综述,并在此基础上对有关发展趋势进行展望。     

高效液相色谱法检测替拉扎明中的有关物质

替拉扎明（TPZ）是一种肿瘤放疗增敏剂,其中已知杂质SR4317为TPZ的合成中间体,SR4330为TPZ的可能降解物。TPZ中有关物质的检测目前尚未见文献报道。本文建立的检测TPZ中有关物质的高效液相色谱法（HPLC）,准确、灵敏、快速,可用于TPZ原料药的质量控制。     

Determination of Dexamethasone in Cosmetics by MEKC

A rapid and reliable method based on micellar electrokinetic capillary chromatography has been developed for the determination of dexamethasone in cosmetics. Effects of buffer composition, concentration and pH, the detection wavelength, separation voltage, and injection time were systematically investigated. The optimum conditions were: 30 mM borax buffer containing 20 mM sodium dodecyl sulfate at pH 9.0, detection at 254 nm, injection time 10 s at a height of 10 cm, and a separation voltage of 15 kV. Under these conditions, the analysis of dexamethasone in cosmetics was carried out within 6 min. The method was validated for stability, precision, linearity and accuracy. Excellent linearity was obtained in the range of 50–1,000 μg mL⁻¹, and acceptable precision, in intra-day and inter-day analysis, was also obtained with relative standard deviation in the range of 0.19–0.86 and 2.50–4.90% for migration time and peak area ratio, respectively. The method was used to analyse eight cosmetic samples purchased locally.