Separation analysis of macrolide antibiotics with good performance on a positively charged C18HCE column

Development and validation of high-performance liquid chromatography method for determination of clarithromycin in pharmaceutical tablets

Clarithromycin is a very important macrolide antibiotic used to treat bacterial infections in human and veterinary medicine. This study reports the development and validation of cost-effective, simple, precise, accurate, and robust high-performance liquid chromatography (HPLC) for the determination of clarithromycin (CLA) in tablets. Reversed-phase chromatography was conducted using a standard column at 55°C with ultraviolet detection at 215 nm. A mobile phase consisting of acetonitrile -2-methyl-2-propanol -potassium phosphate buffer was used at a flow rate of 1.0 mL/min. The proposed method displayed good linearity, precision, accuracy, robustness, and specificity. The present HPLC was compared with capillary electrophoresis and bioassay methods and the results indicated that there was no significant difference between these methods. Moreover, the obtained results demonstrated the validity of the isocratic HPLC, which allows reliable quantitation of CLA in pharmaceutical samples. Thus, it can be used as a substitute alternative methodology for the routine quality control of this medicine, in situations where other methods are less accessible in the laboratory.

Computational modeling, fabrication, and characterization of the deep eutectic solvent-based green molecular cage for selective metronidazole extraction from plasma followed by UHPLC with diode array detector determination

Four ternary deep eutectic solvents were computationally designed and synthesized, being used as candidate functional monomers in metronidazole molecular imprinting polymer synthesis, allowing selective extraction and determination by ultra high performance liquid chromatography with diode array detection. In terms of metronidazole selective extraction, the best results were obtained by (deep eutectic solvent)₂ :(ethylene glycol dimethacrylate)₁₁ , in which deep eutectic solvent is the functional monomer constructed by combining three components in 6:6:2 ratios of choline chloride:ethylene glycol:methacrylic acid. The effects of different parameters on molecular imprinted solid-phase extraction of metronidazole were thoroughly explored through screening design and response surface methodology. The adsorption mechanism findings show that the adsorption data are primarily fitted on the Freundlich model based on higher correlation coefficient. Kinetic experiments have shown that the mechanism of adsorption fits the pseudo-second-order model. The best extraction recovery (96.5%) was obtained in 25-min elution time, desorption temperature of 40°C, and 1.0 mL ACN as eluent. Metronidazole was measured by a validated ultra high performance liquid chromatography with diode array detection method. The calibration of the method was linear in the range of 0.1-10 μg/mL with limits of detection and quantification of 0.03 and 0.1 μg/mL, respectively. The method was successfully applied for the determination of metronidazole in human plasma.

Application of core-satellite polydopamine-coated Fe3O4 nanoparticles-hollow porous molecularly imprinted polymer combined with HPLC-MS/MS for the quantification of macrolide antibiotics

Core-satellite-structured magnetic nanosorbents (MNs) used for the selective extraction of macrolide antibiotics (MACs) were prepared in this study. The MNs (core-satellite polydopamine-coated Fe₃O₄ nanoparticles-hollow porous molecularly imprinted polymer) consisted of polydopamine-coated Fe₃O₄ nanoparticles (Fe₃O₄@PDA) "core" linked to numerous hollow porous molecularly imprinted polymer (HPMIP) "satellites" with bridging amine functional groups. It is worth mentioning that HPMIPs act as "anchors" for selectively capturing target molecules. Polymers were characterized using TEM, SEM, FT-IR, VSM, and TGA and applied as magnetic dispersive solid-phase extraction (MDSPE) sorbents for the enrichment of trace MACs from a complex food matrix prior to quantification by HPLC-MS/MS. Nanocomposites revealed outstanding magnetic properties (36.1 emu g^-1), a high adsorption capacity (103.6 μmol g^-1), selectivity (IF = 3.2), and fast kinetic binding (20 min) for MACs. The multiple advantages of the novel core-satellite-structured magnetic molecularly imprinted nanosorbents were confirmed, which makes us believe that the preparation method of the core-satellite MNs can be applied to other fields involving molecular imprinting technology.

High-throughput method based on a novel thin-film microextraction coating for determining macrolides and lincosamides in honey

A high-throughput method using a new ZIF-8@GO thin-film microextraction coating was established for determining macrolides and lincosamides in honey. The coating preparation parameters (ZIF-8@GO synthesis conditions, coating material proportions, dipping time) and analysis parameters (sample diluent solvent, adsorption and desorption conditions using the ZIF-8@GO coating) were optimized. The optimized parameters were: diluent solvent sodium carbonate/sodium bicarbonate buffer solution (pH 9), adsorption time 45 min, desorption time 5 min, desorption solvent 45:40:15 v/v/v methanol/acetonitrile/water. The extracted targets were determined by ultra-high performance liquid chromatography tandem mass spectrometry. The recoveries of 10 analytes were 67.5-107.2% and the detection and quantification limits were 0.1-0.4 and 0.4-1.4 μg/kg, respectively. The method could analyze 96 samples per run. The minimal manual time and effort is required since the bulk of the sample processing is fully automated. It was a useful and efficient method for monitoring drug residues and was successfully used to analyze real samples.

Purification of tertiary and quaternary alkaloids from Rhizoma Corydalis using reversed-phase/weak cation-exchange mixed-mode class separation combined with preparative C18 and silica based strong cation-exchange chromatography

A new optimization strategy for purification of alkaloids from Rhizoma Corydalis using preparative liquid chromatography was developed, featuring a selective separation of different types of alkaloids into different parts by a reversed-phase/weak cation-exchange mixed-mode column (named C18WCX) at first. The total alkaloids of Rhizoma Corydalis were divided into four fractions with fraction III and IV corresponding to the tertiary type medium bases and the quaternary type strong bases, respectively. For fraction III, a conventional C18 column was used to isolate tertiary alkaloids using acetonitrile and 0.1% phosphoric acid (adjusted with triethylamine to pH 6.0) as mobile phases. High selectivity and symmetrical peak shapes of tertiary alkaloids were obtained, resulting in six main tertiary alkaloids isolated in a single run. As strong bases, quaternary alkaloids often suffer from serious peak tailing problem on conventional C18 columns. Therefore, a silica-based strong cation-exchange (SCX) column was used for purification of fraction IV. On the SCX column, good peak shapes in high sample loading were achieved. Five main quaternary alkaloids were isolated and identified from the fraction in one-step. The procedures presented effective for the preparative isolation and purification of alkaloids from Rhizoma Corydalis.

Application of novel ternary deep eutectic solvents as a functional monomer in molecularly imprinted polymers for purification of levofloxacin

A series of ecofriendly ternary deep eutectic solvents (DESs) with different molar ratios were prepared as candidate functional monomers. Three of the optimal ternary DESs as functional monomers were applied to the preparation of molecularly imprinted polymers (MIPs). After synthesis, the proposed polymers were characterized by elemental analysis (EA), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller surface area measurements (BET) and Fourier transform infrared spectroscopy (FT-IR). These MIPs based on ternary DESs with different molar ratios exhibited different absorption capacities of levofloxacin. A sample of levofloxacin (500ng) was dissolved in a millet extractive (10mL). All MIPs were used as SPE adsorbents to purify the extracts. According to characterization result, the ternary DES-3 (1:3:1.5) was joined in the synthetic process of MIP-1. The green ternary DES-3-based MIPs had the best selectivity recovery for levofloxacin (91.4%) from the millet extractive. The best selectivity of MIP-1 was attributed to the novel monomer (ternary DES) in the preparation of the materials. Overall, ternary DES-based MIPs have potential applications as media in many research areas.

Preparative separation of the polar part from the rhizomes of Anemarrhena asphodeloides using a hydrophilic C18 stationary phase

The goal of this study was to develop a method that utilized a hydrophilic C18 stationary phase in the preparative high performance liquid chromatography to isolate the polar part from the rhizomes of Anemarrhena asphodeloides. The results showed that an initial mobile phase of pure water for the separation could greatly increase the retention and solubility of the polar compounds at the preparative scale. Introducing polar groups on the surface of the hydrophilic C18 column together with the use of optimized mobile phase compositions improved the column separation selectivity for polar compounds. Eleven previously undescribed compounds in Anemarrhena asphodeloides were obtained, indicating that the method developed in this study would facilitate the purification and separation of the polar part of traditional Chinese medicines.