Liquid Chromatographic Assay for Salicylic Acid in Liquid and Semisolid Formulations

Abstract

A high performance liquid chromatographic assay for quantitating salicylic acid (S) in lotion, collodion, ointment and cream formulations is described. The method involved direct determination of S in the liquid dosage forms after appropriate dilutions with the mobile phase. Prior extraction of S from ointments and creams was carried by chloroform. Metronidazole was used as the internal standard and a μ-Bondapak phenyl column with a mobile phase made of 30%, methanol in 5 mM solution of tetrabutylammonium phosphate (pH 7.5) led to an efficient separation. Retention times of about 3 and 7.5 min were obtained for the internal standard and S respectively. The recovery of S from the dosage forms was tested by adding known amounts of S to each preparation and mixing before determination. The mean percentage recovery was in the range of 98–101.1%. The method was found to be accurate, simple and reproducible.     

Liquid Chromatographic Analysis of Various Formulations Containing Emtricitabine

A gradient liquid chromatographic (LC) method for control of emtricitabine (FTC) was validated for the analysis of FTC formulations (capsules and oral solution) and fixed-dose-combination tablets containing FTC [FTC combined with tenofovir disoproxil fumarate (TDF) and FTC combined with TDF and efavirenz (EFV)]. The method is based on the purity test recently prescribed in the International Pharmacopoeia and uses a Hypersil BDS C18 column (25 cm × 4.6 mm i.d.), 5 μm kept at a temperature of 35 °C. Other reversed-phase columns were also investigated. The mobile phases for gradient elution consist of acetonitrile, phosphate buffer and water. The flow rate is 1.0 mL min⁻¹ and UV detection is performed at 280 nm. The method is capable of separating the main components from one another, from the inactive ingredients and from the main degradation products. The method was validated with respect to accuracy, precision, sensitivity and linearity for each component and the solution media were optimized. Finally, commercial FTC capsules, FTC oral solution, FTC/TDF tablets and FTC/TDF/EFV tablets were examined.

     

Liquid Chromatographic Analysis of Various Formulations Containing Emtricitabine

A gradient liquid chromatographic (LC) method for control of emtricitabine (FTC) was validated for the analysis of FTC formulations (capsules and oral solution) and fixed-dose-combination tablets containing FTC [FTC combined with tenofovir disoproxil fumarate (TDF) and FTC combined with TDF and efavirenz (EFV)]. The method is based on the purity test recently prescribed in the International Pharmacopoeia and uses a Hypersil BDS C18 column (25 cm × 4.6 mm i.d.), 5 μm kept at a temperature of 35 °C. Other reversed-phase columns were also investigated. The mobile phases for gradient elution consist of acetonitrile, phosphate buffer and water. The flow rate is 1.0 mL min^?1 and UV detection is performed at 280 nm. The method is capable of separating the main components from one another, from the inactive ingredients and from the main degradation products. The method was validated with respect to accuracy, precision, sensitivity and linearity for each component and the solution media were optimized. Finally, commercial FTC capsules, FTC oral solution, FTC/TDF tablets and FTC/TDF/EFV tablets were examined.     

High Performance Liquid Chromatographic Methods for the Quantitation of Vitamin A Palmitate in Liquid Multivitamin Formulations

Abstract

Several normal-phase high performance liquid chromato-graphic methods for the quantitation of Vitamin A palmitate in liquid multivitamin formulations using both radially-compressed and conventional silica columns are described. The methods are reproducible, require minimal sample preparation and resolve the predominant cis-trans isomers of vitamin A (13-cis, all-trans, 9-cis and 9,13-dicis). Good agreement is obtained between HPLC and USP assay for samples containing a small amount (6% or less) of the vitamin A as the 13-cis isomer.     

Reversed-Phase High-Performance Liquid Chromatographic Determination of Nicotine in Pesticide Formulations

Abstract

A simple and rapid reversed-phase high-performance liquid chromatographic procedure is described for the determination of nicotine in liquid formulations. Samples are diluted with methanol, and naphthalene is added as the internal standard. Peak height ratios obtained from injections of standard and sample filtrates are used for quanti-tation. An eluting solvent of 0.05M (NH₄)₂ HPO4 (pH 7.5) -methanol (40/60, v/v) at a flow of 2 mL/min gives retention times of 3.13 and 6.88 min respectively for nicotine and naphthalene. Sample analysis can be completed in approximately one hour by the method described as compared to 1.5 days required by the Official AOAC gravimetric method (6.176–6.177).     

液态金属电极的电化学储能应用

液态金属电极电导率高,电极界面容易构建,在充放电过程中可有效避免电极结构形变、枝晶生长等问题,在储能电池领域具有重要应用价值. 本文主要讨论了液态金属电极在液态金属电池、钠硫电池和ZEBRA电池中的应用进展,重点介绍了液态金属电池关键材料体系、充放电机制及电池构型等,评述了液态金属电极储能应用中涉及的熔盐电解质、固态陶瓷隔膜、多场影响因素等方面的重要研究进展,分析了高温密封、腐蚀防护等关键问题,明确了液态金属电极在储能电池应用中的发展方向.     

Paintable Room‐Temperature Phosphorescent Liquid Formulations of Alkylated Bromonaphthalimide

Organic phosphors have been widely explored with an understanding that crystalline molecular ordering is a requisite for enhanced intersystem crossing. In this context, we explored the room‐temperature phosphorescence features of a solvent‐free organic liquid phosphor in air. While alkyl chain substitution varied the physical states of the bromonaphthalimides, the phosphorescence remained unaltered for the solvent‐free liquid in air. As the first report, a solvent‐free liquid of a long swallow‐tailed bromonaphthalimide exhibits room‐temperature phosphorescence in air. Doping of the phosphor with carbonyl guests resulted in enhanced phosphorescence, and hence a large‐area paintable phosphorescent liquid composite with improved lifetime and quantum yield was developed.     

Determination of Reserpine in Pharmaceutical Formulations by High Performance Liquid Chromatography

Abstract

High performance liquid chromatography was employed in the assay of reserpine in tablet formulations. A reverse-phase RP-8 column was used and reserpine was separated from its major degradation products and quantitated by peak-height measurement using ultraviolet detection at 254 nm and fluorescence at 330 nm excitation. Tablets analysed were within the official limits even after more than ten years following manufacture.     

Validation of a Reversed-Phase Liquid Chromatographic Method for the Determination of Metronidazole in Transparent Oil-Water-Gel Formulations

A high performance liquid chromatographic (HPLC) method for the determination of metronidazole in new gel formulations was developed and validated according to the recommendations of the International Harmonization Conference. An adaptation of the method described for metronidazole determination in plasma has been used, and the step of extraction has been developed. The method was demonstrated to be linear over a range of 60–140% of nominal label claim, accurate (100.08±0.63%) and precise (0.67% for intra-assay and 1.68% for inter-assay). Single point calibration was chosen for analysis because of its simplicity and wide use in the pharmaceutical industry for content uniformity analysis.     

Hydrogen Storage Using Liquid Organic Carriers

Russian Journal of Applied Chemistry - Published data on experimental and theoretical studies of systems for long-term storage and transportation of hydrogen, based on liquid organic hydrogen...     

液体有机氢化物储氢研究进展*

液体有机氢化物储氢技术利用不饱和液态芳烃和对应环烷烃之间的加\脱氢反应,不仅可用于长周期的季节性储氢,还可用于远距离输氢,以解决地区间能源分布不均的问题。本文分析了该技术的基本原理和特点,并着重就其中的脱氢反应,从催化剂的开发、催化反应机理以及反应模式等层面,进行了分析讨论。关于催化剂,主要从催化剂的活性组分、颗粒分散度、载体种类、孔结构和表面性质与催化活性、结焦失活和耐硫性之间关系的关系进行了分析。关于反应模式,重点讨论了过热液膜态反应、非稳态脉冲喷射进料反应和膜分离反应等几种有利于改善传热传质条件、打破平衡限制的催化脱氢反应模式。并展望了液体有机氢化物储氢的研究和发展方向。     

Stability Indicating Reversed-Phase High Performance Liquid Chromatography Method for Determination of Impurities in Ofloxacin Tablet Formulations

A gradient reversed-phase high performance liquid chromatography (RP-HPLC) method was developed for separation and quantitation of impurities in pharmaceutical dosage form of ofloxacin tablets. The developed method was a stability indicating test method for estimation of related impurities generated during synthesis, formulation, and storage of ofloxacin tablets. Forced degradation studies were performed on ofloxacin tablets including acid hydrolysis (5.0 M hydrochloric acid), base hydrolysis (5.0 M sodium hydroxide), oxidation (30% hydrogen peroxide), heat (105°C) humidity degradation 25°C/92% RH/119 b & 40 min, and photolytic degradation (2600 Lux/119 h & 40 min). From the degradation study, the degradation was found between 0–15%. Limit of detection and limit of quantification were established in terms of percentage for all potential impurities. The recovery studies were conducted on finished dosage samples (tablets) for all potential impurities and the average percentage recovery was ranged from 90.8 to 104.2. Placebo interference was verified by taking the placebo (composition of excipients) equivalent to weight in portion of test preparation and no interference was observed. The method was validated and found to be linear, accurate, precise, specific, robust, and reliable. The developed method was established in accordance to ICH guidelines.     

An Intrinsic Photothermal Liquid for Light Detection and Energy Storage

Photothermal materials (PTMs) have been intensively investigated in the fields of photothermal conversion. Superior to solid PTMs, liquid PTMs are leading the trends in satisfying the demands of high flexibility and easy recycling. Successful examples of liquid PTMs are mostly formulated by dispersing solid PTMs in solvents, but suffer from the problems of phase segregation and solvent pollution. In this work, a low-cost formulation is proposed, which involves an oxidative product of ethyl oleate by iodine. It is an intrinsic liquid PTM, preserving the fluidic nature as well as possessing considerable ability for photothermal conversion. In addition to understanding the mechanism of light absorption in the visible and even near infrared windows, two examples are presented to demonstrate the great potential of liquid PTMs in broad areas such as light sensing and energy storage.     

液相色谱法直接测定可湿性制剂苯菌灵

研究了苯菌灵浓度在低温下的相对稳定性，提出了一种简单的直接测定可湿性制剂苯菌灵的高效液相色谱方法。该法的前处理是将有机溶剂冷却到－１５℃，然后用此溶剂来配制苯灵菌灵试液，并在每次进样后都将此试液保存在－１５℃的低温下，从而使得分析结果良好。定量方法的线性范围为０．１￣３ｇ／Ｌ，相对标准偏差为０．４％。     

Determination of Meloxicam in Tablet Formulations by Ultraviolet Spectrophotometry and High-Performance Liquid Chromatography

ABSTRACT

Assay procedures based on UV spectrophotometry and high-performance liquid chromatography (HPLC) have been developed for the determination of meloxicam in tablet formulations. The HPLC method used a reversed-phase C18 column with 0.05M Tris acetic acid buffer - tetrabutylammonium reagent–acetonitrile as eluent, and UV detection at 360nm with isoxicam as the internal standard. The UV method was based on measuring an acidic solution of the drug at 341nm. A comparison was established in terms of linearity, sensitivity, precision, and accuracy. Both methods were simple and rapid. HPLC was more precise and more accurate, the UV technique was slightly faster.     

High Performance Liquid Chromatographic Analysis of Rifampin and Related Impurities in Pharmaceutical Formulations

Abstract

High pressure liquid chromatography was employed for the assay of rifampin in capsules. A reverse phase RP-2 column and a mobile phase of 48% methanol, 5% tetrahydrofuran and 47% 0.05 M ammonium formate (pH 7.3) were used with detection at 254 nm. Rifampin was separated from all its major degradation products and quantitated.     

High-Performance Liquid Chromatographic Method for the Simultaneous Determination of Four Flavonols in Food Supplements and Pharmaceutical Formulations

A method using high-performance liquid chromatography with diode array detection (HPLC-DAD) as a powerful separation technique has been developed for the simultaneous determination of the four flavonols rutin, quercetin, kaempferol and isorhamnetin in food supplements and pharmaceutical formulations. The chromatographic separation was achieved in 36?min using a Symmetry C₁₈ column (250?×?3?mm; 5?µm) as the stationary phase and a mixture of methanol, acetonitrile, and pH 2.5 aqueous acetic acid as the mobile phase in gradient elution mode. The analytical wavelengths were 256?nm for rutin, quercetin and isorhamnetin, and 368?nm for kaempferol. An ultrasound-assisted extraction protocol was performed using methanol as solvent. The detection and quantification limits were lower than 0.03?µg mL^?1 and 0.08?µg mL^?1, respectively. The inter-day and intra-day precisions were less than 4.8 and 5.1%, respectively, and the average recoveries were in the range from 96 to 107%. The method was applied for the determination of the studied flavonols in food supplements and pharmaceutical preparations. The satisfactory recovery values demonstrate the potential of the developed method for the determination of the analytes in these samples. In addition, the method is suitable for routine quality control due its ease of operation.     

光致变色液晶高分子信息存储材料研究进展

本文系统阐述了光致变色液晶高分子的研究概况、光信息存储机理以及信息存储应用方面的研究进展。     

Reverse-Phase High Performance Liquid Chromatographic Determination of Clidinium Bromide and Chlordiazepoxide in Tablet Formulations

Abstract

Clidinium bromide is a quaternary ammonium anticholinergic agent with peripheral effects. It is commercially available in combination with chlordiazepoxide. There is no official compendial method available for the analysis of both compounds concurrently. Conventional methods for determining both compounds involve extensive extraction and thus are time-consuming, and lack precision. The analytical scheme described in this paper provides a fast and reliable reverse-phase HPLC for chlordiazepoxide and clidinium bromide in pharmaceutical combinations. The mobile phase was 0.04 M ammonium acetate in 70% acetonitrile solution with 1% dimethylformamide (pH 6). The column was microPak MCH-10 (300.0 mm × 4.0 mm), UV detection at 254 nm and benzophenone was used as internal standard. The method was confirmed for linearity, recovery, specificity, accuracy, and applicability.     

Simultaneous High Performance Liquid Chromatographic Determination of Amitriptyline Hydrochloride and Perphenazine in Tablet Formulations

Abstract

A rapid, precise, and accurate high performance liquid chromatographic procedure is presented for the simultaneous determination of amitriptyline hydrochloride and perphenazine in two component tablet formulations. The related compounds of amitriptyline hydrochloride were separated, making the determination specific for amitriptyline hydrochloride and perphenazine. The method was used for the assay and content uniformity for three commercial products. The mobile phase was 0.02 M ammonium acetate in aceto-nitrile: methanol: water (45:15:40) solution and the pH was adjusted to 5.0 by acetic acid. The column was a supelcosil (5 μm) LC-8-DB (250 mm × 4.6 mm i. d). The method was tested for linearity, recovery, and specificity.