毛细管电泳法分离四环素及其杂质

用毛细管电泳方法分离四环素和它的主要杂质４－差向四环素，脱水四环素，４－差向脱水四环素和２－乙酰基－２－脱酰胺四环素，相对次要的杂质氯四环素和脱甲四环素也能被分离。并系统研究了缓冲液ｐＨ，缓冲液浓度以及毛细管温度和电压对分离的影响。紫外检测波长是２７０ｎｍ，测定的相对标准偏差为１．９％。所得结果与ＨＰＬＣ方法进行了比较     

高纯金中杂质元素的电感耦合高频等离子体原子发射光谱法测定

研究了萃取金后用ＩＣＰ－ＡＥＳ法测定微量Ｐｔ、Ｐｄ、Ｒｈ、Ｉｒ、Ａｇ等２８个杂质元素的方法。元素间的干扰用等效浓度法校正。杂质元素标准加入回收率为７５％～１１８％；相对标准偏差为４．３％～２０％；取样量为２．５ｇ时，测定下限为５×１０＾５％～２×１０＾－４％。     

2－氰基－4－硝基苯胺的薄层色谱紫外光度分析

本文应用薄层色谱紫外光度法，测定了产品中的主要成分２－氰基－４－硝基苯胺和杂质，得到了满意的分析结果。与经典化学法比较，这种方法具有简单、快速、精确的特点。回收率９９％～１０１％，相对标准偏差０．７％～１．１％，２－氰基－４－硝基苯胺含量在０～１３５μｇ／２５ｍＬ范围内遵守比耳定律。     

感耦等离子体质谱法（ICP—MS）测定高纯氧化镝中痕量稀土杂质

本文报道用２－乙基己基膦酸单酯萃淋树脂为固定相，ＨＣｌ为淋洗液的萃取色谱法研究了高纯Ｄｙ２Ｏ３中的痕量稀土杂质和Ｄｙ２Ｏ３基体的分离条件，并用ＩＣＰ－ＭＳ法测定了高纯Ｄｙ２Ｏ３中的１４个稀土杂质，稀土元素的测定限为０．００１－０．００５ＩＣＰ－ＭＳ法测定了高纯Ｄｙ２Ｏ３     

萃取色谱分离—原子发射光谱测定超高纯氧化铥,氧化镱和氧化镥中痕…

用２－乙基己基膦酸单２乙基己酯萃取色说分离－原子发射光谱测定超高纯Ｔｍ２Ｏ３，Ｙｂ２Ｏ３，Ｌｕ２Ｏ３中痕量稀土杂质，可用于纯度为９９．９９９９％－９９．９９９９９％Ｔｍ２Ｏ３，Ｙｂ２Ｏ３，ｌＵ２ｏ３的纯分分析，１４个稀土杂质的回收率在６７％－１３３％之间；相对标准偏差５．１％－２３．２％，分离周期１０－１３ｈ。     

高纯氧化钪中稀土杂质的电感耦合等离子体质谱法测定

研究了用电感耦合等离子体质谱法测定高纯氧化钪中１５个稀土杂质的方法。考察了基体效应及内标的作用，采用Ｉ或Ｃｓ为内标可很好补偿基体ＳＣ的影响。方法检测限为０．０１３－０．０８５ｎｇ／ｍｌ，加料回收率为９１．２％－１０５．７％，相对标准偏 １．４％－８．１％。     

高纯氧化铕中微量稀土杂质的化学光谱测定

将高纯Ｅｕ２Ｏ２通过Ｐ５０７萃淋树脂分离富集，分离掉大量基体Ｅｕ２Ｏ３剩下微量稀土杂质用碳粉吸附，加ＫＢＨ４作载体进行光谱测定，本方法可测定９９．９９９９％，纯度的Ｅｕ２Ｏ３中微量稀土杂质。     

Lewis酸催化1,4-脱水-2,3-二-氧-(对迭氮基苯甲基)-α-D-核糖的选择性开环聚合反应

在低温下用三氟化硼乙醚催化１，４－脱水－２，３－二－氧－（对迭氮基苯甲基）－α－Ｄ－核糖（ＡＤＡＢＲ）的阳离子选择性开环聚合反应，首次合成了具有１，５－开环α－结构的聚合物。单体ＡＤＡＢＲ由１，４－脱水－α－Ｄ－核糖在ＤＭＦ溶剂中与对溴甲基迭氮基苯反应获得。聚合物的结构由比旋光度、１Ｈ－ＮＭＲ和１３Ｃ－ＮＭＲ及ＩＲ谱确认。用五氟化锑为催化剂则得到了同时含有α－呋喃单元和β－吡喃单元混合结构的聚合物。研究了催化剂及其用量、聚合反应时间对聚合反应的影响，讨论了聚合反应机理。为研究１，４－脱水－２，３－二－氧－（对迭氮基苯甲基）－α－Ｄ－吡喃核糖的聚合活性以及便于测试迭氮基的含量对聚合物光刻性能的影响，还初步研究了单体ＡＤＡＢＲ与１，４－脱水－２，３－二－氧－苯甲基－α－Ｄ－吡喃核糖（ＡＤＢＲ）的共聚反应。从共聚物的结构分析可以认定共聚物具有１，５－α－结构，并且单体１，４－脱水－２，３－二－氧－苯甲基－α－Ｄ－吡喃核糖在实验条件下具有较高的活性。     

2—（4—氨酰基—2—噻唑基）—1,4—脱水—L—木糖醇及其氟代衍 …

用计算机分析模拟方法研究了２－（４－氨酰基－２－噻唑基）－１，４－脱水－Ｌ－木糖醇及其氟代衍生物的糖基构象，计算结果显示，６个碳核苷类似物的糖基构象均为Ｓ型。核磁共振谱和晶体Ｘ射线衍射结果与计算结果相吻合。     

磷酸三丁酯色层分离—电感耦合等离子体原子发射光谱法测定U3Si2

本法对Ｕ３Ｓｉ中２２个微量杂质元素的测定，进行了较系统的实验研究，取样１００ｍｇ时，Ａｌ、Ｃａ、Ｃｄ、Ｃｒ、Ｃｕ、Ｆｅ、Ｈｆ、Ｉｎ、Ｍｇ、Ｍｎ、Ｍｏ、Ｎｂ、Ｎｉ、Ｐｂ、Ｓｎ、Ｔａ、Ｔｉ、Ｖ、Ｙ、Ｚｎ和Ｚｒ的测定范围５μｇ／ｇ－８００μｇ／ｇ，回收率为９４％－１０５％，ＲＳＤ（ｎ＝８）０．４％－１．２％。     

Separation of tetracycline and its related substances by capillary zone electrophoresis

Tetracycline was separated from its main impurities 4-epitetracycline, anhydrotetracycline, 4-epianhydrotetracycline, chlortetracycline, and demethyltetracycline by capillary electrophoresis. Systematic method development was performed in which following parameters were consecutively optimized: type and pH of the buffer, buffer concentration, type and concentration of organic modifier, voltage and temperature. Qualitative and quantitative aspects of the method are compared with liquid chromatography.     

Analysis of process impurities in the basic drug SB-253149 using capillary electrophoresis and on-line mass spectrometric detection

Capillary electrophoresis with on-line electrospray ionisation mass spectrometry (CE/ESI-MS) has been used to identify process impurities in a batch of the anti-atherosclerotic drug, SB-253149. The impurities were separated from the main drug compound by capillary electrophoresis (CE) using an ammonium formate buffer at low pH in an untreated fused silica capillary. The CE method was initially developed using UV as the detection mode and then later structural elucidation work was achieved using an ion trap mass spectrometer. To maintain peak resolution and peak shape when the CE system was coupled to the mass spectrometer, a modified capillary cassette linked to a coaxial sheath flow electrospray ionisation (ESI) interface was used. By performing MS/MS experiments in conjunction with chemical knowledge of the reactivities of SB-253149, it was possible to propose molecular structures for impurities detected in the batch of SB-253149. The results from this study revealed that most of the process impurities in SB-253149 were dimeric derivatives of the parent molecule as well as trace levels of the starting material. This type of information was vital in process control and optimisation for the synthetic route for this drug.     

Capillary zone electrophoresis method for the determination of famotidine and related impurities in pharmaceuticals

A simple and rapid capillary zone electrophoresis (CZE) method with UV detection has been developed for the determination of famotidine and its potential impurities in pharmaceutical formulations. The electrophoretic separation of these compounds was performed using a fused silica capillary and 37.5mmolL(-1) phosphate buffer pH 3.5 as the electrolyte. Under the optimised conditions, six impurities could be resolved from the famotidine peak in less than 7min. The calibration curves obtained for the seven compounds were linear over the concentration range investigated (from 1.5 to 78.5microg mL(-1)). The intra- and inter-day relative standard deviations for the migration times and corrected peak areas were less than 2% and 5%, respectively. The detection limits were found to be 0.09microg mL(-1) for famotidine, and from 0.1 to 0.62microg mL(-1) depending on the impurities. The method has been successfully applied to the determination of famotidine in commercial dosage forms.     

Purity control of oxytetracycline by capillary electrophoresis

The applicability of capillary electrophoresis for the purity control of oxytetracycline (OTC) was investigated. OTC is a broad-spectrum antibiotic belonging to the group of the tetracyclines. Several related substances can be present due to fermentation or degradation, such as 4-epioxytetracycline, -apooxytetracycline, β-apooxytetracycline, anhydrooxytet racycline, 2-acetyl-2-decarboxamidooxytetracycline, tetracycline and 4-epitetracycline. Using fused-silica capillaries, the influence of buffer type, buffer pH and buffer concentration were investigated. In all cases 1 mM EDTA was added to prevent metal-ion complexation. The influence of the buffer counter-ion type was examined. Consequently, some instrumental parameters were changed such as capillary length and diameter as well as capillary temperature and applied voltage. The following method is finally proposed: fused-silica capillary, l (effective length) = 38 cm, L (total length) = 44 cm, 50 μm I.D.; buffer, sodium carbonate 20 mM-EDTA 1 mM, pH 11.25; voltage, 10 kV; temperature, 10°C. Linearity, limit of detection and limit of quantitation were determined as well as the relative standard deviations for all the analytes involved. This method is less selective then existing liquid chromatographic methods but it may be used as a complementary tool in purity control and stability studies.     

Approach to method development and validation in capillary electrophoresis for enantiomeric purity testing of active basic pharmaceutical ingredients

A chiral capillary electrophoresis system allowing the determination of the enantiomeric purity of an investigational new drug was developed using a generic method development approach for basic analytes. The method was optimized in terms of type and concentration of both cyclodextrin (CD) and electrolyte, buffer pH, temperature, voltage, and rinsing procedure. Optimal chiral separation of the analyte was obtained using an electrolyte with 2.5% carboxymethyl-beta-CD in 25 mM NaH2PO4 (pH 4.0). Interchanging the inlet and outlet vials after each run improved the method's precision. To assure the method's suitability for the control of enantiomeric impurities in pharmaceutical quality control, its specificity, linearity, precision, accuracy, and robustness were validated according to the requirements of the International Conference on Harmonization. The usefulness of our generic method development approach for the validation of robustness was demonstrated.     

Enantioseparation of warfarin and its metabolites by capillary zone electrophoresis

A capillary zone electrophoresis (CZE) method with direct ultraviolet (UV)-absorbance detection is presented for the simultaneous enantiomeric separation of warfarin and its main metabolites, including warfarin alcohols, 4'-, 6-, and 7-hydroxywarfarin, using highly sulfated beta-cyclodextrin (HS-beta-CD) as the chiral selector. This chiral separation method was optimized in terms of the electrophoretic parameters, which included the concentration of HS-beta-CD used, the type and composition of organic modifier added to the background electrolyte (BGE) buffer, and the BGE buffer pH. Chiral separation of warfarin and its major metabolites was achieved with high resolution, selectivity, efficiency, repeatability, and reproducibility. This optimized chiral analysis of warfarin along with its metabolites was completed within a satisfactory electrophoresis time of 20 min.     

Non-aqueous capillary electrophoresis with diode array and electrospray mass spectrometric detection for the analysis of selected steroidal alkaloids in plant extracts

A capillary electrophoresis (CE) assay has been developed for the quantitation and determination of the impurity profile of the potassium channel blockers 3,4-diaminopyridine and 4-aminopyridine. The compounds were separated from related substances using a capillary of 30 cm effective length, a 50 mM phosphate buffer, pH 2.5 and an applied voltage of 25 kV. The assay was validated with respect to specificity, linearity, range, limits of quantitation and detection, precision and robustness. The method allows the detection and quantitation of impurities at the 0.05% level. The feasibility of the assay was demonstrated by analyzing a commercial sample of 3,4-diaminopyridine. All known related substances could be detected in this sample with the present CE method.     

Capillary electrophoresis determination of diatrizoic acid and its impurities in diatrizoate radiopaque solutions

A capillary electrophoresis method has been developed for the separation and determination of diatrizoic acid (DTZA) and its four mono- and diiodo degradation products (2-iodo,4-iodo, 2,4-diiodo, and 2,6-diiodo-3,5-diacetamidobenzoic acid) in radio-paque solution for injection (RSI). DTZA and its degradants were assayed in suitable dilutions without pretreatment. Optimum conditions included the use of low-pressure sample injection (6 s), sample and standard solutions with a molarity less than that of the separation buffer, and adjustment of the buffer molarity to obtain a current of 50 A at a constant 15kV separation voltage. After each six runs or less, the inlet and outlet buffer were replaced with more buffer from the same batch. When the method was applied to a sample of SI levels of 5–10 mg/ml were found for each of the mono and diiodo impurities. The optimum method showed a precision (peak area measurement) in the range 1.7–7.2% RSD, depending on the concentration. A linear correlation coefficient of 0.997 was obtained over a DTZA concentration range of 5–60 mg/mL.     

Determination of oxytetracycline and some impurities in plasma by non-aqueous capillary electrophoresis using solid-phase extraction

Summary The potential of a non-aqueous, capillary electrophoresis (NACE) system for separating oxytetracycline from three of its impurities—tetracycline, 4-epioxytetracycline and 4-epitetracycline—using UV detection has been studied. The running buffer was: 25 mM sodium acetate, 1 mM EDTA, methanesulfonic acid, pH 4, dissolved in MeOH-ACN (50∶50,v/v). The method was also used to determine these compounds in pig plasma. A solid-phase extraction (SPE) procedure as a clean-up step has also developed. For this we tested Sep Pak C₁₈, LiChrolut EN and OASIS cartridges. OASIS cartridges were best. Recoveries were 90–100% for all compounds except EOTC which had a recovery of 74%.