光化学荧光分析法测定头孢氨苄的研究

在ｐＨ４．０的缓冲溶液中，头孢氨苄在紫外光照射下能发生光化学反应，形成具有荧光的产物，λｅｘ为３４５ｎｍ，λｅｍ为４３２ｎｍ。在头孢氨苄浓度为０．１－４．０μｇ／ｍｌ范围内，荧光强度与浓度呈良好的线性关系，由此建立了头孢氨苄的光化学荧光测定法。方法的检出限为０．０１μｇ／ｍｌ，相对标准偏差为０．９３％。本法简便，快速且灵敏度高，可用于尿液中头孢氨苄含量的测定。     

离子选择性电极法测定药剂中的头孢氨苄

基于头孢氨苄在０．１０ｍｏｌ／Ｌ ＮａＯＨ介质中,沸水浴降解２００ｍｉｎ后,能生成硫醇化合物,利用硫离子选择电极研究了测定头孢氨苄条件,其浓度在６．０×１０＾－５￣１×１０＾－２ｍｏｌ／Ｌ范围,电位Ｅ与浓度对数呈线性关系,并将此方法用于胶囊中头孢氨苄的测定,回收率为１０４．０％。     

分光光度法测定头孢氨苄

头孢氨苄与茚三酮在酸性水溶液中能发生显色反应。表观摩尔吸光系数为是７．９５×１０＾３Ｌ．ｍｏｌ＾－１．ｃｍ＾－１。作者详细研究了该反应的条件，应用拟定的方法测定药物制剂含量与药典方法一致，回收率在９９％以上。     

反相高效液相色谱法同时测定多种头孢菌素的研究(I)

建立了同时分离测定６种头孢菌素（头孢米诺、头孢羟氨苄、头孢克罗、头孢氨苄、头孢拉定和头孢西丁）的高效液相色谱法。流动相为Ｖ（５０ ｍ ｍ ｏｌ／Ｌ的磷酸二氢钾缓冲液,ｐＨ ３．４）ｖＶ（乙腈）＝ ８７．５ｖ１２．５的混合液,色谱柱为ＨｙｐｅｒｓｉｌＯＤＳＣ１８５ μｍ ,２００ ｍ ｍ ×４．６ ｍ ｍ ｉ．ｄ．,紫外检测波长为２５４ ｎｍ , 流速为１．０ ｍ Ｌ／ｍ ｉｎ。各个组分的线性范围：头孢米诺为１６４ ｎｇ～１６．４ μｇ,头孢羟氨苄为９９ ｎｇ～９．９３４ μｇ,头孢克罗为１０４ ｎｇ～１０．３５８ μｇ,头孢氨苄为１２２ ｎｇ～１２．２２４ μｇ,头孢拉定为１０７ ｎｇ～１０．７０２ μｇ,头孢西丁为１１５ ｎｇ～１１．５０６ μｇ。各组分的方法回收率及相对标准偏差：头孢米诺为（１０３．５３±１．２）％ ,头孢羟氨苄为（９９．３５±０．７）％ ,头孢克罗为（１０１．３９±０．７）％ ,头孢氨苄为（１０１．４５±１．８）％ ,头孢拉定为（９８．６８±１．９）％ ,头孢西丁为（９７．５９±１．４）％ 。     

顶空气相色谱法测定头孢氨苄中有机残留溶剂甲醇

采用顶空气相色谱法测定了头孢氨苄中有机残留溶剂甲醇的含量；以0．5mol/L氢氧化钠溶液为溶剂制备供试品溶液，以ChrompackCP-Si 8CB弹性石英毛细管柱为分离柱，研究了盐析效应、顶空加热温度和顶空热平衡时间对甲醇测定的影响；当添加水平为96．0μg时，回收率为98％～104％，测定相对标准偏差RSD为1．2％(n=6)，检出限为0．5mg／L(信噪比为3：1)，甲醇质量浓度为9．6～153．6mg／L时，线性相关系数为0．9999。     

银微盘电极上头孢氨苄降解产物的伏安行为及其应用

基于头孢氨苄降解产物中含有巯基，能与Ａｇ＾＋生成难溶化合物的特性，在银微盘电极上研究了ＣＥＸ降解产物的伏安行为，探讨了电极反应的机理。运用示差脉冲溶出伏安法，在０．１ｍｏｌ／Ｌ ＨＡｃ－ＮａＡｃ介质中，ＣＥＸ降解产物的还原峰电流与ＣＥＸ浓度于８．０×１０＾－８－７．０×１０＾－６ｍｏｌ／Ｌ范围内呈良好线性关系；检测限为１．０×１０＾０８ｍｏｌ／Ｌ；测定了头孢氨苄胶囊中ＣＥＸ含量为９２．０％，与药典     

头孢氨苄与苯醌类试剂的荷移反应

本研究了头孢氨苄与对苯醌和四氯苯醌的荷移反应，实验指出，头孢氨苄与对苯醌反应是在乙醇介质中进行，与四氯苯醌反应则在硼砂缓冲液中进行，两种络合物λｍａｘ值分别是４８７ｎｍ和３４６ｎｍ；表观摩尔吸光系统分别是１．３７×１０＾３和１．０２×１０＾４Ｌ．ｍｏｌ＾－１．ｃｍ＾０１；比尔定律线性范围分别是１０－１６０ｍｇ／Ｌ和３－３０ｍｇ／Ｌ，其组成比均是１：１，应用拟定的方法测定头孢氨苄制剂含量，结果与标     

流动注射-化学发光法测定头孢氨苄

头孢氨苄在H2SO4溶液中降解后,其产物可在酸性条件下与Ce（Ⅳ）产生化学发光反应,罗丹明6G对该反应有较强的增敏作用。据此建立了流动注射－化学发光法测定头孢氨苄的新方法。该方法的线性范围为0.10－10.0mg/L检出限为0.06mg/L,相对标准偏差(n=11,c=1.00mg/L）为0.85。方法用于药物中头孢氨苄含量的测定,其结果与标准方法一致,回收率为96％－106％。     

树脂吸附法回收头孢氨苄工艺研究

为了从头孢氨苄结晶废母液中回收产品,采用大孔树脂吸附法对回收工艺进行了研究,比较了HZ818,HZ832,HZ801,HZ816,D4020,X-5等6种大孔吸附树脂对头孢氨苄的吸附性能,筛选出了高吸附性能的树脂,同时对头孢氨苄在HZ816吸附柱上的动态吸附-解吸过程进行了研究.其结果是:大孔吸附树脂HZ816能更好地分离回收头孢氨苄,其吸附量在45.4mg/mL左右,40％的乙醇(pH 2.0)可以将吸附在树脂柱上的头孢氨苄有效解吸,解吸率达94.5％,解吸液经结晶、干燥等后续处理可得到符合中国药典要求的产品.大孔吸附树脂HZ816是回收头孢氨苄的一种理想的吸附剂,该工艺简捷,具有很好的工业化前景.     

大网格吸附剂提取头孢氨苄

本文研究了用大网格吸附剂提取头孢氨苄的方法，包括吸附剂和解吸剂的筛选，吸附条件和解吸条件的考察。确定了用H—103型树脂在pH5、流速1／10（V／V／min）条件下吸附；用50％丙酮在pH1．5、流速1／30（V／V／min）条件下解吸。吸附容量可达75mg／ml，是国内报道过的CAD—40的3倍，是国外报道过的DiaionHP－20的3．8倍，解吸率可达92％以上。     

药物头孢氨苄分子模板聚合物水中结合性质的研究

采用分子模板技术合成了以头孢氨苄为模板分子以三氟甲基丙烯酸和４－乙烯基吡啶同时为功能单体的分子模板聚合物。将得到的棒状聚合物研磨过筛后,运用平衡结合实验研究了头孢氨苄分子模板聚合物的结合性质,Ｓｃａｔｃｈａｒｄ分析表明,在所研究的浓度范围内,在聚合物中形成了两类不同的结合位点。头孢氨苄分子模板聚合物与其化学组成相同的非模板聚合物相比,有很高的结合容量。底物选择性实验表明,与其它结构相似的药物相比,     

头孢氨苄在碳糊电极上的电化学行为及其分析研究

用循环伏安法和线性扫描伏安法研究了头孢氨苄在碳糊电极上的电化学行为,考察了不同电解质溶液、pH以及扫描速率等的影响。实验表明:在2.0 mol·L-1HCl支持电解质中,头孢氨苄的降解产物在-0.45 V(vs.SCE)处的电化学还原反应为2电子与2质子参加的受吸附控制的不可逆过程。还原峰电流与头孢氨苄的浓度的平方根在1.8×10-8～3.0×10-4mol·L-1范围内呈良好的线性关系,回收率在95.7%～101.5%范围,检出限(S/N=3)为1.0×10-8mol·L-1。并探讨了头孢氨苄在电极上的反应机理。     

Micellar electrokinetic capillary chromatography for the separation of cefalexin and its related substances

Micellar electrokinetic capillary chromatography (MEKC) was examined for analysis of cefalexin and its related substances. Good selectivity was obtained with two different buffer solutions: a sodium acetate buffer (50 mM, pH 5.25) containing sodium dodecyl sulfate (50 mM SDS) or sodium phosphate buffer (40 mM, pH 7.0) containing 100 mM SDS. Both methods permit cefalexin to be completely separated from its ten related substances within 20 min. The robustness of the method, using pH 5.25 acetate buffer, was examined by means of a full-fraction factorial design to test the influence of buffer pH, concentration of SDS and buffer concentration. The parameters for validation such as linearity, precision, limit of detection and limit of quantitation are also reported. The results show that method 1 is suitable for the analysis of cefalexin.     

Immobilization and sustained release of cefalexin on MCF nano-mesoporous material

Abstract

Mesocellular foams (MCF) silica nanometer mesoporous molecular sieve was successfully synthesized by hydrothermal route. This method used poly(ethylene glycol)-block-poly(propyl glycol)-block-poly(ethylene glycol) as template, tetraethyl orthosilicate as silica source and 1, 3, 5-trimethylbenzene as pore-expanding agent to prepare nano mesoporous MCF in acidic medium. The MCF mesoporous material was characterized by powder X-ray diffraction (XRD), infrared (IR) spectroscopy, low temperature nitrogen adsorption-desorption at 77?K, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The effects of pH, temperature, adsorbent dosage, cefalexin dosage and contact time on the immobilization of cefalexin were studied. Under the optimized conditions, MCF has the best effect on the drug immobilization. The maximum immobilization amount of cefalexin in MCF nano-mesoporous material is 498.8?mg/g. The behavior of adsorption of cefalexin by MCF belongs to multilayer heterogeneous adsorption, which accords with the Freundlich adsorption isotherm. In the adsorption process, all the ΔH⁰, ΔS⁰ and Gibbs free energy change ΔG⁰ are less than zero, indicating that the adsorption process is spontaneous, exothermic entropy decreasing reaction at ordinary temperature. Kinetic investigation showed that the adsorption process of cefalexin on MCF belongs to the pseudo-second-order kinetic process. The release laws of composite material cephalexin-MCF in the simulated body fluid, gastric and intestinal fluid were investigated, respectively. The maximum cumulative release rate in simulated body fluid was 99.4% at 18?h. The maximum cumulative release rate in the simulated gastric juice was 48.7% at 6?h and in the simulated intestinal fluid the maximum cumulative release rate of 61.9% was achieved at 8?h. These release processes satisfy the zero-order ordered kinetic process.     

反相高效液相色谱法同时测定多种头孢菌素的研究(I)

 建立了同时分离测定６种头孢菌素（头孢米诺、头孢羟氨苄、头孢克罗、头孢氨苄、头孢拉定和头孢西丁）的高效液相色谱法。流动相为Ｖ（５０ｍｍｏｌ／Ｌ的磷酸二氢钾缓冲液,ｐＨ３．４）ｖＶ（乙腈）＝８７．５ｖ１２．５的混合液,色谱柱为ＨｙｐｅｒｓｉｌＯＤＳＣ１８５μｍ,２００ｍｍ×４．６ｍｍｉ．ｄ．,紫外检测波长为２５４ｎｍ,流速为１．０ｍＬ／ｍｉｎ。各个组分的线性范围：头孢米诺为１６４ｎｇ～１６．４μｇ,头孢羟氨苄为９９ｎｇ～９．９３４μｇ,头孢克罗为１０４ｎｇ～１０．３５８μｇ,头孢氨苄为１２２ｎｇ～１２．２２４。     

Development and validation of a reversed-phase column liquid chromatographic method for the determination of five cephalosporins in pharmaceutical preparations

A new, simple, rapid, and precise RP-HPLC method has been developed and validated for the determination of five cephalosporins, namely, cefalexin, cefoperazone, ceftriaxone, ceftazidime, and cefepime. The method has been applied successfully for simultaneous determination of cefalexin in a binary mixture with sodium benzoate in a suspension, and cefoperazone in a binary mixture with sulbactam in vials. Chromatographic separation was achieved on a Waters microBondapak C18 column (250 x 4.6 mm id, 10 pm particle size) using the mobile phase monobasic potassium phosphate (50 mM, pH 4.6)-acetonitrile (80 + 20, v/v) with UV detection. A flow rate of 1 mL/min was applied. Linearity, accuracy, and precision were found to be acceptable over the concentration range of 30-300, 3-30, and 15-120 microg/mL for the studied cephalosporins, sodium benzoate, and sulbactam, respectively. The optimized method proved to be specific, robust, and accurate for QC of the cited drugs in their pharmaceutical preparations.     

湿消解-电感耦合等离子体发射光谱法测定药用胶囊中的铬含量

以硝酸作为消解液,采用湿消解-电感耦合等离子体发射光谱法(ICP-AES)测定药用胶囊中的铬含量.在0～80 ng/mL范围内,铬的浓度与发射光强度呈良好的线性关系,相关系数r=0.999 98,检出限为1.42 ng/mL.对3个浓度水平的铬标准溶液进行平行测定,测定结果的相对标准偏差为1.43％～1.79％(n=6),加标回收率为93.1％ ～110.0％.该方法可以用于药用胶囊中铬的日常检测.     

Stability, dynamics, and selectivity in the assembly of hydrogen-bonded hexameric capsules

Fluorescence resonance energy transfer (FRET) was employed to monitor the dynamics of hydrogen-bonded hexameric assemblies formed from resorcin[4]arenes and pyrogallol[4]arenes. Studies were designed to provide further insights into the degree of assembly and stability of these self-assembled capsules at the micro- to nanomolar concentration ranges that are not accessible by NMR studies. The results of this investigation reveal factors that influence the self-assembly of these macrocycles into hexameric capsules. Pyrogallolarenes are very sensitive to the concentration of mixing, with an increase in the equilibration half-life from 36 min at 250 nM to 156 min at 10 microM. The resorcinarenes showed little difference in exchange rates over the same concentration range. The temperature of mixing of the macrocycles was found to be important for both systems with a 12-fold increase in exchange rates over a 20 degree range for the pyrogallolarenes and a 2-fold rate increase for the resorcinarenes over the same temperature range. The stability of the capsules to polar additives such as methanol was probed, with the pyrogallolarenes requiring a higher percentage (1.6% v/v in dichloromethane) of methanol to disassemble the capsules than the resorcinarenes (1.0% v/v in dichloromethane). Pyrogallolarenes assemble in both anhydrous and wet solvents whereas water-saturated solvents are necessary to facilitate the formation of resorcinarene capsules. In addition to these studies, evidence of strict self-sorting in the formation of distinct pyrogallolarene and resorcinarene hexamers was obtained.     

Acid-Base Properties of Cefalotin,Cefazoline, and Cefalexin

The acid-base properties of cefalosporines, such as cefalotin, cefazoline, and cefalexin, were studied. The concentration constants of their acid dissociation at 20°C on the background of 0.1, 0.4, 0.7, and 1.0 M solutions of KCl and KNO₃ were determined. Thermodynamic dissociation constants were calculated. The semiempirical PM3 quantum-chemical method was used to calculate the size of the ionic forms of the cefalosporines in the energetically preferred conformations.     

Determination of Cefdinir by a stability-indicating liquid chromatographic method

A simple, fast, specific, stability-indicating, and precise reversed-phase liquid chromatographic method was developed for the determination of Cefdinir in its different dosage forms, i.e., capsules and suspensions. The method was developed and optimized by analyzing the placebo preparation, formulations, and degraded samples of the drug substance according to the International Conference on Harmonization. The proposed method can successfully separate the drug from degradation products formed under stress conditions along with pharmaceutical ingredients such as preservatives. The developed method was used successfully to determine Cefdinir in capsules and Insta-use suspensions. The developed method was found to be linear for a concentration range of 6-14 microg/mL. Average recoveries obtained with the method were 99.3 +/- 0.4 and 99.6 +/- 0.4% for Insta-use suspensions and capsules, respectively. The method was shown to be specific, precise, and robust.