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Σάββατο, 29 Ιουνίου 2019

Chromatographia

Ajay Kumar Mishra (Ed): Smart Ceramics: Preparation, Properties, and Applications


Raymond Hill, Terry Kenakin and Tom Blackburn (Eds): Pharmacology for Chemists—Drug Discovery in Context


Congress, Conferences, and Workshops


Identification and Quantification of Related Impurities of a Novel Ketolide Antibiotic Nafithromycin

Abstract

Nafithromycin (NFT, WCK 4873) is a novel antimicrobial drug being developed to treat infections caused by Gram-positive bacteria. It is a second-generation drug of the lactone ketolide class. A mass spectrometry-compatible reversed-phase liquid chromatographic method was developed to separate and identify the impurities in NFT. Forced degradation (FD) study ensured specificity of the method and revealed the probable degradation products. Seven process impurities and five degradation products were chromatographically resolved and identified based on the protonated molecule peak and product ions. Process impurities were synthesized and characterized for identity and purity. Separation was achieved on the XTerra C18 stationary phase using the binary gradient method. Mobile phase 'A' constituted of a mixture of an aqueous solution of ammonium acetate (pH 9.0), acetonitrile and methanol in the ratio of (48:27:25, v/v/v). Mobile phase 'B' constituted of an aqueous solution of ammonium acetate (pH 9.0) and acetonitrile in the ratio of (05:95, v/v). The method was validated for accurate and precise quantification of the impurities. The developed method was employed for quality control and stability studies of the NFT drug substance used for pre-clinical and clinical studies.

Graphical Abstract



Simultaneous Capillary Liquid Chromatography Determination of Drugs in Pharmaceutical Preparations Using Tunable Platforms of Polymethacrylate Monolithic Columns Modified with Octadecylamine

Abstract

Nowadays, analytical techniques tend to develop cheap and green approaches to reduce the costs and minimize environmental impacts. In this study, poly(glycidyl methacrylate-co-ethylene dimethacrylate) monoliths were prepared in capillary columns (0.25 mm i.d. × 20 cm length) as reactive and tunable platforms, and then simply functionalized based on a ring-opening reaction of epoxide with octadecylamine. The columns were successfully used as reversed-phase stationary phases for determination of ascorbic acid, paracetamol, caffeine, aspirin, and ibuprofen in pharmaceutical combinations. The synthesized monoliths have been estimated by FT-IR spectroscopy, SEM and specific surface area; also, the porous and hydrodynamic properties have verified the differences before and after modification. While the columns before modification were unable to separate the drugs, the columns after amination allowed for the complete separation of the five drugs in about 10 min at 23 µL min−1 flow rate with chromatographic resolution more than 2.12. The developed assay showed excellent suitability (RSDs < 2.6%), wide linear ranges (0.07–300 µg mL−1), sensitive detection limits (0.022–0.060 µg mL−1), good repeatability (RSDs < 4.76%) and acceptable columns reproducibility (RSDs < 18.58%). The method was successfully applied for commercial pharmaceutical preparations; the average recovery values were found to be in the range of 98.03–104.54% (RSDs < 5.51%). The satisfactory recovery percentages along with the perfect correlation between the retentions of standard compounds and the active ingredients extracted from the commercial tablets indicate the accuracy and selectivity of the developed method. The prepared columns and validated method were finally compared with previous reports, particularly commercial C18 stationary phases. This is a very useful comparison due to the structural similarity between the prepared polymeric materials and C18 particulate stationary phases. The prepared capillary columns exhibited various advantages such as the fast separation time, wide linear ranges, low analysis costs, and trivial environmental wastes.

Graphical Abstract



A Covalent Organic Framework-Derived Hydrophilic Magnetic Graphene Composite as a Unique Platform for Detection of Phthalate Esters from Packaged Milk Samples

Abstract

The development of functional nanocomposites based on covalent organic framework (COF) is still highly important. In this work, a novel COF-functionalized hydrophilic magnetic graphene (magG@PDA@TbBd) was prepared through a facile and efficient route and applied as a unique magnetic solid-phase extraction matrix for phthalate esters analysis. The obtained magG@PDA@TbBd exhibited excellent water dispersibility, large surface area, strong magnetic response, regular mesoporous structure and strong π–π electron system. Based on these properties, the newly prepared composite displayed outstanding reusability and potential performances on phthalates analysis with good linearity (50–8000 ng mL−1) and reliable recoveries (91.4–105.2%). Limit of detection (LOD) varied from 0.004 ng mL−1 to 0.02 ng mL−1, and relative standard deviation (RSD) for intra-day and inter-day were less than 4.4% and 6.7%, respectively. More interestingly, the newly obtained magG@PDA@TbBd was utilized to analyze 9 PAEs in packaged milk samples. This work may open-up a direction in design and construction of functionalized COF-derived composites.



Determination of Semicarbazide in Foodstuffs by HPLC with Fluorescence Detection Using 2-Formylphenylboronic Acid as Derivatization Reagent

Abstract

Semicarbazide (SEM), a widespread toxic food contaminant, is a stable metabolite of antibiotic nitrofurazone and widely found in some foodstuffs, such as shrimp or bread. A simple and sensitive method was developed for the determination of SEM by high-performance liquid chromatography with fluorescence detection. SEM can be labeled by 2-formylphenylboronic acid (FPBA) within 7 min at room temperature. The FPBA-SEM derivative was identified with electrospray ionization mass spectrometer in positive mode. It was found that the MS mainly gave [M + H]+ at m/z 189.8, and MS/MS gave a high abundance of a fragment ion at m/z 146.9. The derivative was completely separated on a reversed-phase Eclipse XDB-C18 column within 5 min, and excellent selectivity was obtained with fluorescence detection at specific excitation and emission wavelengths (λex = 265 and λem = 320 nm). The new method showed the lower limit of detection of 0.36 μg L−1 and the limit of quantitation of 1.17 μg L−1. Linearity with correlation coefficient of 0.995 and satisfactory accuracy ranging from 94.42 to 106.78% were obtained. This proposed method was successfully applied to determination of SEM in bread and shrimp. The developed method should have a powerful potential for the rapid determination of trace SEM in foodstuffs.

Graphical Abstract



Polyethyleneimine Functionalized Multi-walled Carbon Nanotubes-Based Solid Phase Extraction for Selective Screening of Carboxylic Acid Compounds in Natural Products

Abstract

In this work, by adopting polyethyleneimine functionalized multi-walled carbon nanotubes as the absorbent, a solid phase extraction based method for fast and selective screening of carboxylic acid compounds was developed. The structure and morphology of the polyethyleneimine functionalized multi-walled carbon nanotubes were confirmed via scanning electron micrograph, transmission electron microscopy, Fourier transform infrared spectra and X-ray photoelectron spectroscopy. And the proposed approach was successfully applied to screen carboxylic compounds from the crude extract of Perilla frutescens. As a result, seven polyhydric compounds with carboxyl including caffeic acid, luteolin-7-O-diglucuronide, apigenin-7-O-diglucuronide, sagerinic acid, scutellarein-7-O-glucuronide, rosmarinic acid, and apigenin-7-O-glucuronide were favorably screened out from compounds without carboxyl group. Similar screening results were also obtained via generalizing the method to the crude extract of Chrysanthemum. This strategy could serve as a rapid and efficient pathway for preliminary screening of certain types of compounds from complex natural products.



Py–GC–MS and PCA Analysis Approach for the Detection of Illegal Waste Combustion Processes In Central Heating Furnaces

Abstract

Domestic waste combustion in central heating furnaces is illegal in many countries, including Poland, but unfortunately still occurs. These activities have a negative influence on the environment and human health. The local nature of this process makes it difficult to effectively counteract this phenomenon. Information campaigns about the impact of domestic waste combustion in central heating furnaces, especially the impact on human health, are necessary, but undertaking parallel control activities is much more important. To control activity, support is necessary to develop a suitable method to confirm domestic waste combustion in central heating furnaces. In the present preliminary study, we have investigated two methods. The first method is indirect, it is based on the analytical pyrolysis of organic residues in ash and provides direct information on the type of plastic subjected to combustion. The second method is based on the principal component analysis (PCA) of polycyclic aromatic hydrocarbon (PAH) concentrations in ash samples. Special attention was paid to sixteen PAHs: naphthalene, acenaphthene, acenaphthylene, fluorene, anthracene, phenanthrene, fluoranthene, pyrene, chrysene, benzo(a)anthracene, benzo(a)pyrene, benzo(e)pyrene, benzo(b+k)fluoranthene, dibenzo(a,h)anthracene+ indeno(1,2,3-cd)pyrene, benzo(g,h,i)perylene, and perylene.



Dehydration of a Water Stationary Phase as a Novel Separation Gradient in Capillary Supercritical Fluid Chromatography

Abstract

A novel alternative to gradient elution in capillary supercritical fluid chromatography (SFC) based upon the systematic removal of a water stationary phase from the column, using a pure CO2 mobile phase, is introduced. By adjusting the flow of water used to humidify the system, the stationary phase can be removed at different rates and this results in proportionately faster analyte elution. As well, the phase can be readily restored within a few minutes. The method demonstrates good reproducibility with analyte retention times yielding an RSD of 1.2% in consecutive trials. Further, it provides results that compare well to a conventional pressure program in capillary SFC, but without the problematic convolution of system pressure and flow rate. The technique also demonstrated the ability to refocus analytes into sharper peaks, resulting in a 30-fold increase in their peak height. This effect can improve detection limits and also allow ionizable analytes like amines and dicarboxylic acids to be eluted with improved peak shape. Results indicate that systematic removal of a water stationary phase from the column is an interesting and potentially effective alternate means of controlling and improving analyte elution in capillary SFC.

Graphical Abstract



Alexandros Sfakianakis
Anapafseos 5 . Agios Nikolaos
Crete.Greece.72100
2841026182
6948891480

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