Determination of Gentamicin Sulphate Composition and Related Substances in Pharmaceutical Preparations by LC with Charged Aerosol Detection

A new, simple and repeatable liquid chromatography method with charged aerosol detection (LC-CAD) for the determination of gentamicin sulphate composition and related substances has been developed. Gentamicin lacks of chromophores, therefore its determination is quite problematic. Using a universal CAD enables to achieve good separation without sample derivatization. Mass spectrometry was employed to confirm the LC-CAD peak profile. The proposed method was validated and applied for the determination of gentamicin sulphate composition and related substances in pharmaceutical preparations.     

超分子化学在药物共晶中的应用

药物共晶是一种新兴的药物晶型, 一个给定的活性药物分子通过形成共晶, 一方面可以大大丰富其结晶形式, 另一方面可以改善其物化性质及临床疗效. 本文从超分子化学的角度对药物共晶进行了综述, 列举了一系列通过氢键超分子合成子进行药物共晶设计和制备的研究实例, 旨在促进超分子化学和药学的交叉融合.     

Analysis of Barbiturate Mixtures Using HPLC with Diode Array Detection

Abstract

A study has been conducted on the HPLC analysis of barbiturate mixtures in which coeluting components with similar UV spectra could be distinguished by diode array detection. Mixtures containing phenobarbital and barbital in combination from about 0.25 to 0.00025 mg/mL each were measured using the spectral overlay, absorbance ratio, peak maximum absorbance and purity parameter techniques. The most sensitive of the standard methods available was absorbance ratio plotting in which the presence of 0.0125 mg/mL barbital could be distinguished from phenobarbital at 0.2375 mg/mL.     

Enzymatic Reaction Coupled with Flow-Injection Analysis with Charged Aerosol,Coulometric, or Amperometric Detection for Estimation of Contamination of the Environment by Pesticides

Because excessive using of pesticides poses a threat to the environment and to human health, development of low-cost and sensitive methods for analysis of pesticides in the environment is needed. Several bacteria can release halide ions from the molecules of halogenated hydrocarbons. This can be used in a device for analysis of halogenated hydrocarbons in the environment by quantification of the halide anions. Here we directed our attention to selecting an instrument for detection of chloride anions. We tested three different detectors, amperometric, and coulometric, both coupled with flow-injection analysis and charged aerosol, coupled with high performance liquid chromatography. Detection limits (3 × S/N) for measurement of chloride anions by use of these detectors was 30 μM (charged aerosol), 100 nM (coulometric), and 1 nM (amperometric). Because of its lowest detection limit for chloride anions and the many technical possibilities of miniaturization, the amperometric detector was used to test of effect of different cations on the chloride signal under the optimized experimental conditions (working electrode potential −365 mV; “Current R” 5 μA; mobile phase 0.2 M phosphate buffer, pH 6; flow rate 0.5 mL min⁻¹). NaCl, SrCl₂, NH₄Cl, and CsCl were tested as sources of chloride anions. We then used the detector to detect chloride anions catalytically cleaved from 1-chlorohexane by the enzyme haloalkane dehalogenase LinB from the bacterium Sphingobium japonicum UT26. The activity of the enzyme increased with increasing reaction temperature until the maximum was observed at 39°C. The results obtained were in good agreement with data obtained by colorimetric detection.

     

Validated Stability-Indicating Method for Alendronate Sodium Employing Zwitterionic Hydrophilic Interaction Chromatography Coupled with Charged Aerosol Detection

Alendronate sodium is widely used in the treatment of osteoporosis and Paget’s disease. The HPLC method development for alendronate sodium, in particular, is challenging owing to the absence of chromophoric group and its high polarity. In the present study, a short and simple isocratic method was developed involving hydrophilic interaction liquid chromatography, coupled with a charged aerosol detector. The developed method was validated according to the ICH Q2(R1) guideline and was successfully applied for the analysis of a marketed formulation containing the drug.

     

Analysis of Nereistoxin Using HPLC And Electrochemical Detection

Abstract

Nereistoxin blocks nicotinic cholinergic transmission, but the exact mechanism by which this dithiolane blocks nicotinic acetylcholine receptors is not clear. One possibility is that nereistoxin is reduced in vivo and the resulting product, dihydronereistoxin, reduces a disulfide bond in the region of the receptor where acetylcholine binds. Other possibilities include that nereistoxin oxalate as supplied is not pure and contains dihydronereistoxin, or that nereistoxin acts as a simple competitive antagonist. We report here a method for simultaneous detection of both nereistoxin and dihydronereistoxin using π reversed-phase, ion-pair high-performance liquid chromatography with electrochemical detection. The standard curve for nereistoxin is linear to 400 pmol, and the detection limit is 10 pmol. The working electrode response is stable for up to 60 injections. Reduction of nereistoxin to dihydronereistoxin by NaBH₄ was 92% complete under the conditions reported here, but reoxidation occurs slowly upon standing at room temperature. No dihydronereistoxin was detected in commercial samples of nereistoxin oxalate.     

Performance Evaluation of Charged Aerosol and Evaporative Light Scattering Detection for the Determination of Ginsenosides by LC

A sensitive LC-CAD method was developed for simultaneous determination of seven major triterpenoid saponins, namely ginsenosides Rg₁, Re, Rb₁, Rc, Rb₂, Rb₃ and Rd in Panax ginseng C. A. Meyer, a commonly used traditional Chinese medicine. This CAD method was evaluated in sensitivity, linearity and reproducibility compared to ELSD and UV. It was found the developed method has improved sensitivity, linearity and reproducibility compared to ELSD. This method was successfully applied to analyze the ginsenosides in ten samples of Panax ginseng. The validation results indicated that the improved method can be utilized as another approach for quality control of P. ginseng.     

双三元液相色谱-串联电喷雾检测器用于中药注射剂大分子物质筛查研究

A size exclusion chromatography method ( SEC) was established for the screening of macromolecules in traditional Chinese medicine (TCM) injections. In the experiment, TCM was collected through 0. 45μm ...     

Chromatographic Fingerprint Analysis of the Flowers of Abelmoschus manihot Using HPLC with Photodiode Array Detection

Abstract

A simple and valid chromatographic fingerprint analysis method was developed using high‐performance liquid chromatography‐photodiode array detection for the quality analysis of the flowers of Abelmoschus manihot. For the first time, the feasibility and advantages of employing chromatographic fingerprint were investigated and demonstrated for the evaluation of the flowers of A. manihot by systematically comparing chromatograms with professional analytical software recommended by State Food and Drug Administration. Our results revealed that the chromatographic fingerprint combining similarity evaluation could be used efficiently for the identification and quality assessment of raw herbs of the flowers of A. manihot from different sources.     

Pharmaceutical Analysis for Environmental Samples: Individual and Simultaneous Determination of Ciprofloxacin,Ofloxacin and Norfloxacin Using an HPLC with Fluorescence and UV Detection with a Wetland Soil Matrix

Abstract

Two HPLC methods were developed for individual and simultaneous determination of ciprofloxacin, norfloxacin and ofloxacin for use in laboratory experiments producing large numbers of samples (100 s to 1000 s). Individual compound detection produced retention times between 1.5 and 2 min and simultaneous detection between 6.5 to 8 min. The methods are compatible with complex geomatrices, e.g. a wetland soil. These methods provide 1) detection limits in the low parts per-billion range; 2) decrease in retention times of 5–10 times for single compounds, and up to 2 times for simultaneous detection over published methods; and 3) require no solid phase extraction.     

微流控芯片非接触电导检测的研究进展

微流控芯片是一种现代分析新方法,非接触电导检测作为其重要检测技术之一,近年在仪器研制和应用等方面都取得了可喜的进展。本文重点对微流控芯片非接触电导检测的影响因素和应用的研究进展进行总结和评述。引用文献56篇。     

Investigation of polar organic solvents compatible with Corona Charged Aerosol Detection and their use for the determination of sugars by hydrophilic interaction liquid chromatography

A range of organic solvents (ethanol, isopropanol and acetone) has been investigated as alternatives to acetonitrile and methanol when used in conjunction with Corona Charged Aerosol Detection (Corona CAD). These solvents have been evaluated with regard to their effect on the response of the Corona CAD. Three dimensional response surfaces were constructed using raw data showing the relationship between detector response, analyte concentration and percentage of organic solvent in the mobile phase, using sucralose or quinine as the test analyte. The detector response was non-linear in terms of analyte concentration for all solvents tested. However, detector response varied in an approximately linear manner with percentage of organic solvent over the range 0–40% for ethanol or isopropanol and 0–80% for acetone and methanol. The chromatographic performance of the various solvents when used as aqueous–organic mobile phases was evaluated for isocratic and gradient separations of sugars and sugar alcohols by hydrophilic interaction liquid chromatography (HILIC) using an Asahipak NH2P-504E column coupled with Corona CAD detection. It was found that whilst acetonitrile provided the highest column efficiencies and lowest detection limits of the solvents studied, acetone also performed well and could be used to resolve the same number of analytes as was possible with acetonitrile. Typical efficiencies and detection limits of 5330 plates m⁻¹ and 1.25 μg mL⁻¹, respectively, were achieved when acetone was used as the organic modifier. Acetone was utilised successfully as an organic modifier in the HILIC separation of carbohydrates in a beer sample and also for a partially digested dextran sample.     

Quantitative Analysis of Toosendanin in the Fruit of Melia toosendan Sieb. Et Zucc (Meliaceae) by High-Performance Liquid Chromatography Coupled with Charged Aerosol Detection

In this work, a simple and rapid high-performance liquid chromatography coupled with charged aerosol detector (HPLC-CAD) method was first developed for the quantitation of toosendanin, the major constituent of the dried fruit of Melia toosendan Sieb. Et Zucc. Samples were well separated on an Agilent ZOBAX SB C18 column (4.6 mm × 250 mm, 5 μm) by isocratic elution using 33 % acetonitrile and 67 % water containing 0.1 % formic acid (v/v) at the flow rate of 1.0 mL min⁻¹. The nitrogen inlet pressure of the charged aerosol detector (CAD) was 35 psi, and the nebulizer chamber temperature was 35 °C. The established method was well validated. Satisfactory linearity was achieved (r ² > 0.9997) in a relatively wide concentration range (5–500 μg mL⁻¹). The intra- and inter-day precisions, repeatability, and stability of the method were good with relative standard deviations (RSDs) of 1.05, 2.23, 2.39, and 2.03 %, respectively. The method also showed excellent accuracy with recovery rates of 97.42–101.87 %. Particularly, CAD showed much better sensitivity (LOQ 4 μg mL⁻¹) than evaporative light scattering detector (LOQ 100 μg mL⁻¹) for toosendanin’s determination. The established method was further applied in the quantitation of toosendanin in 39 batches of raw and stir-fried toosendan fructus. The HPLC-CAD method was rapid and accurate, and could be used for the routine analysis and quality control of toosendan fructus and its preparations.

     

Benefits and Pitfalls of HPLC Coupled to Diode-Array,Charged Aerosol,and Coulometric Detections: Effect of Detection on Screening of Bioactive Compounds in Apples

The new screening method for rapid evaluation of major phenolic compounds in apples has been developed. Suitability of coupling HPLC/UHPLC separation with the diode-array detection and universal charged aerosol detection with respect to the presence of interfering substances was tested. Characteristics of both detection techniques were compared and method linearity, limits of detection and quantitation, and selectivity of them determined. Student t-test based on slopes of calibration plots was applied for the detailed comparison. The diode-array detection provided the best results regarding sensitivity and selectivity of the developed method in terms of evaluation of phenolics profiles. The response of the charged aerosol detector was negatively affected by co-eluting substances during rapid-screening analyses. Coulometric detection was used for advanced characterization of extracts in terms of antioxidant content and strength to obtain more complex information concerning sample composition. This detection also allowed evaluation of unidentified compounds with antioxidant activity. HPLC/UHPLC separation using a combination of diode-array and coulometric detectors thus represented the best approach enabling quick, yet complex characterization of bioactive compounds in apples.     

SEC Assay for Polyvinylsulfonic Impurities in 2-(N-Morpholino)ethanesulfonic Acid Using a Charged Aerosol Detector

A quantitative method for measuring polyvinylsulfonic acid (PVS) concentrations in 2-(N-morpholino)ethanesulfonic acid (MES) is described here. Utilizing a TSK-GEL G2500PW_xl SEC column, PVS elutes in the void volume as a sharp peak, yielding group separation between PVS and MES. 20 mM formic acid is used as the mobile phase, as its volatility is compatible with a charged aerosol detector. The low pH mobile phase also suppresses residual negative charges on the stationary phase, reducing the ion exclusion effect commonly observed in aqueous SEC. This method was qualified to measure PVS concentration in MES per International Conference on Harmonization guidelines, using multiple MES lots and other Good’s buffers such as N-(2-acetamido)-2-aminoethanesulfonic acid and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid.     

Analysis of Disopyramide by HPLC with Uv Detection

Abstract

A simple and sensitive method has been developed for the determination of disopyramide employing reverse phase high performance liquid chromatography with UV detection. p-Chlorodisopyramide was used as an internal standard. The retention times of disopyramide and the internal standard at an elution rate of 1.8 ml/min were 6.28 and 8.78 min, respectively.     

Novel Method for HPLC Analysis of Triterpenic Acids Using 9-Anthryldiazomethane Derivatization and Fluorescence Detection

Triterpenic acids are a group of secondary plant metabolites which are part of the cuticular waxes covering fruits, leaves, and flowers. To date, quantitative analysis of these compounds has often been conducted using high-performance liquid chromatography coupled with spectrophotometric detection or mass spectrometry; however, these methods have some major drawbacks. This paper reports a new method of analysis implementing derivatization with 9-anthryldiazomethane and fluorescence detection. The method consists of the extraction of analytes from a matrix, purification with anion exchanging SPE columns, and an optional step of the alkaline hydrolysis of triterpenic acid esters. The paper also describes a fast and easy method for the synthesis of the derivatization agent. The detection limits of the method presented are approximately 100-fold lower than in a similar method using ultraviolet spectrophotometry as the mode of detection. The recovery and repeatability of the method are at satisfactory levels.     

Analysis of Dexamethasone Acetate in Pharmaceutical Formulations by HPLC

Abstract

A rapid and effective high-pressure liquid chromatographic method has been developed for the quantitative determination of dexamethasone 21 acetate in pharmaceutical formulations. Sample preparation employs a simple extraction procedure and analysis is carried out on a reversephase chromatographic system using a LiChrosorb RP 18 column and a water-acetonitrile as mobile phase. The extraction procedure gives quantitative recovery and chromatographic results show that drug levels of as 0.1 ppm can be conveniently analyzed without significant background interferences.