Electrochemical Reduction of Metronidazole and Its Determination in Pharmaceutical Dosage Forms by D.C. Polarography

Abstract

A simple d.c. polarographic method has been developed for the determination of metronidazole in dosages forms. In Robinson - Britton buffer (pH 4.38) and in presence of 1.60 × 10^?3 % Triton X-100, the drug produced a well defined 4-electron polarographic wave followed by another wave of about half the height of the first wave. The current is proportional to the concentration and permits the drug to be determined by d.c. polarography in the concentration range 5.0 × 10^?5 -7.0 × 10^?4 M. Results obtained by the proposed method are in excellent agreement with that provided by the USP-XX method. A rapid, sensitive and accurate polarographic method for the determination of metronidazole in the tablets which are produced locally is proposed.     

HPLC测定盐酸二甲双胍肠溶片的含量

建立高效液相色谱法测定盐酸二甲双胍肠溶片含量的方法.采用Hypersil ODS2色谱柱(4.6mm×250mm,5μm),0.05％庚烷磺酸钠溶液(用10％磷酸溶液调节pH值至4.0)∶乙腈(84∶16)为流动相,紫外检测波长233nm;流速1.0mL/min;柱温为30℃.盐酸二甲双胍在0.11-10.70μg/m...     

多波长线性回归-零吸收分光光度法在复方制剂中的应用

本文建立一种全新的光谱分析方法 ,多波长线性回归 -零吸收分光光度法 ,并应用于复方新诺明片剂的含量测定。样品经乙醇溶解稀释后 ,不需分离 ,直接在选定波长组 ( n=5 )下 ,分别测定一组吸光度值 ,经线性回归处理后计算出磺胺甲口恶唑与甲氧苄啶含量。二组分的平均回收率分别为 10 1.4± 0 .9%和 97.3± 0 .4 %。本法测量误差小 ,优于传统的双波长分光光度法 ,可用于未经分离的双组分和多组分混合体系的含量测定。     

紫外分光光度法测定非诺贝特片含量的不确定度评定

分析了非诺贝特片含量测定过程中样品的称样量、含量的重复性测量、样品的稀释体积和紫外分光光度法测量吸光度等因素对含量测定不确定度的影响。量化了各分量的相对标准不确定度,进而得出合成标准不确定度和扩展不确定度。建立的不确定度评定方法适用于分光光度法测定非诺贝特片含量的不确定度分析。     

对乙酰氨基酚氯美扎酮分散片溶出度研究

采用高效液相色谱法测定对乙酰氨基酚氯美扎酮分散片溶出度。以稀盐酸24mL加水至1000mL为溶媒,转速为100r.min-1,取样时间为15min,在227nm波长处测定其溶出度。对乙酰氨基酚平均回收率为100.6%,RSD=0.59%;氯美扎酮平均回收率为100.6%,RSD=0.86%。3批样品15min溶出度均在90%以上,且溶出均一。本法简便、准确、可靠,可用于该制剂的溶出度测定。     

HPLC测定对乙酰氨基酚氯美扎酮分散片的含量

采用KromasilC4(200×4.6mm;5μm),以甲醇-水-冰乙酸(27∶63∶0.9)为流动相,检测波长为227nm,对乙酰氨基酚和氯美扎酮浓度分别在0.035—0.212mg/mL和0.008—0.048mg/mL范围内线性关系良好(r=0.9996和r=0.9999),平均回收率分别为100.0%和100.0%。本法简便,快速、重现性好,回收率高,且可同时测定对乙酰氨基酚氯美扎酮分散片中两组分的含量,并可用于其质量控制。     

Validation of the RP–HPLC method for analysis of hydrochlorothiazide and captopril in tablets

A rapid and sensitive reverse-phase high performance liquid chromatography (RP–HPLC) method with ultra-violet (UV) detection for a routine control of hydrochlorothiazide and captopril in tablets was developed. The chromatographic system Hewlet Packard 1100 consisted of a HP 1100 pump, HP 1100 UV–VIS detector and HP ChemStation integrator. The samples were introduced through a Rheodyne injector valve with a 20-L sample loop. The isocratic system consisted of a Beckman Ultrasphere ODS 4.6 mm x 15 cm, 5-m-particle column and a mobile phase containing methanol/water (45:55 v/v). The pH of the mobile phase was adjusted to 3.8 with 85% ortophosphoric acid. Quantitation was accomplished using the internal standard method. At the selected conditions, the other excipients of the tablets did not interfere in the assay of active substances. The developed RP–HPLC method was validated, so linearity, precision, accuracy, robustness, limit of quantitation and limit of detection were investigated. For the robustness test, three factors were considered: the composition of the mobile phase , the pH of the mobile phase, and temperature. With the aid of response surface metodology (RSM), it was possible to precisely define the robustness of the method.     

A sensitive and rapid assay for 4-aminophenol in paracetamol drug and tablet formulation, by flow injection analysis with spectrophotometric detection

4-Aminophenol (4AP) is the primary degradation product of paracetamol which is limited at a low level (50 ppm or 0.005% w/w) in the drug substance by the European, United States, British and German Pharmacopoeias, employing a manual colourimetric limit test. The 4AP limit is widened to 1000 ppm or 0.1% w/w for the tablet product monographs, which quote the use of a less sensitive automated HPLC method. The lower drug substance specification limit is applied to our products, (50 ppm, equivalent to 25 μg 4AP in a tablet containing 500-mg paracetamol) and the pharmacopoeial HPLC assay was not suitable at this low level due to matrix interference. For routine analysis a rapid, automated assay was required. This paper presents a highly sensitive, precise and automated method employing the technique of Flow Injection (FI) analysis to quantitatively assay low levels of this degradant. A solution of the drug substance, or an extract of the tablets, containing 4AP and paracetamol is injected into a solvent carrier stream and merged on-line with alkaline sodium nitroprusside reagent, to form a specific blue derivative which is detected spectrophotometrically at 710 nm. Standard HPLC equipment is used throughout. The procedure is fully quantitative and has been optimised for sensitivity and robustness using a multivariate experimental design (multi-level ‘Central Composite’ response surface) model. The method has been fully validated and is linear down to 0.01 μg ml⁻¹. The approach should be applicable to a range of paracetamol products.     

复方厚朴片生产工艺实验研究的优化方法

为优化复方厚朴片的生产工艺，先通过预实验找出六个影响因素及其范围，对各因素如何搭配采用随机办法安排实验方案，按五种优良性准则从方案中选出较优且运行次数最少者，用ＳＡＳ回归过程分析试验结果     

氯霉素片中氯霉素含量的HPLC法测定

采用高效液相色谱法测定氯霉素片中氯霉素的含量，用C18柱为分离柱，水-甲醇-冰醋酸（体积比55：45：0.1）为流动相，检测波长278nm，氯霉素进样量在1.6-2.4μg范围内与主峰面积线性关系良好（r=0.9996），平均回收率为101％，重复进样相对标准偏差0.40％（n=7）。