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Liposome capillary electrokinetic chromatography was used to investigate the interactions between three β‐blockers of different hydrophobicity and various liposome solutions. The studied β‐blockers comprised alprenolol, propranolol, and carvedilol. The composition of the liposome solutions, containing 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphocholine, 1,2‐dioleoyl‐sn‐glycero‐3‐phos‐phoethanolamine, 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phospho‐l‐serine, and cholesterol in various molar ratios, was designed by a response surface methodology‐central composite design approach. Subsequently, after conducting the liposome capillary electrokinetic chromatography experiments and determining the retention factors from the electrophoretic mobilities of the compounds, and further calculating the distribution coefficients, an analysis of variance was performed. After extracting the statistical models, optimal operational conditions were obtained based on the developed models. To further investigate the interactions between the β‐blockers and the liposomes, nanoplasmonic sensing experiments were carried out on two different liposome systems. The overall results demonstrate the strong influence of cholesterol and 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phospho‐l‐serine on the distribution coefficients. [ABSTRACT FROM AUTHOR]

Abstract: In this work we elucidated the applicability of phosphonium-based ionic liquids (ILs) as pseudostationary phase in electrokinetic capillary chromatography (EKC) with UV-detection. The phosphonium ILs studied contain bromide, chlorine, or tosylate ions, as counter ions, and alkyl side chains of variable length on the phosphorous atom. The effects of the type and concentration of the IL, pH, ionic strength, and type of background electrolyte solution on the electroosmotic flow (EOF) and on the effective electrophoretic mobilities of some neutral model analytes were investigated and large variations in the migration times were observed. Especially the IL employed remarkably affected the strength and direction of the EOF Successful separations were obtained for neutral aromatic singly substituted analytes, namely benzene, toluene, phenol, and nitrobenzene. The results demonstrated the potential of capillary electromigration methods for rapid interaction studies between ILs and analytes, which is useful for the development of novel materials for sample preparation and separation purposes or for novel catalyst and chemical processing studies. [Copyright &y& Elsevier]

Interactions between Intralipid dispersion and local anesthetics (bupivacaine, prilocaine, and lidocaine) were investigated. The amount of bupivacaine (the most cardiotoxic analyte of the local anesthetics studied) entrapped in Intralipid in the presence of plasma was studied using an off-line filtration and solid phase extraction method combined with capillary zone electrophoresis for quantification of free unbound bupivacaine. To confirm interactions between the analytes and Intralipid at lower concentrations, direct injection mass spectrometry was used. The use of immobilized Intralipid chromatography-atmospheric pressure ionization–ion trap mass spectrometry in the study of interactions between drugs and Intralipid dispersion is demonstrated. Finally, interactions between Intralipid dispersion and local anesthetics were investigated by electrokinetic capillary chromatography. The electrophoretic mobility of the Intralipid dispersed phase was calculated using the iterative procedure and a homologous series of alkyl phenyl benzoates (C1–C6), and the retention factors for the analytes were determined. [ABSTRACT FROM AUTHOR]

A novel, comprehensive two-dimensional asymmetric field-flow fractionation-liquid chromatographic system is described (AsF1FFF-RPLC). The interface is based on a switching valve, and the whole sample is analyzed in both dimensions. The system proved to be repeatable and quantitative in the characterization of egg white proteins. Four peaks at 4, 5.5-6.0, 7.5-8.0, and 10.0-11.0 nm, and corresponding to lysozyme, ovalbumin, transferrin, and a dimer of transferrin, were obtained in the AsFIFFF first-dimension system. Lysozyme also produced an additional peak, which overlapped with ovalbumin. Twelve compounds were separated in the LC second-dimension system. Identifications were made with the help of standards (ovalbumin, ovotransferrin, lysozyme) and by comparison of the peak areas, particle sizes, and retention data with values given in the literature. The effect of heat on egg white denaturation was studied, and the unfolding of peptide bonds of the protein was found to be pronounced when the sample was heated in phosphate solution. [ABSTRACT FROM AUTHOR]

The structural resemblance of liposomes to natural cell membranes has caused them to be employed in liquid chromatographic and capillary electromigration techniques to study the interactions between analytes and phospholipid membranes. Phospholipids and liposomes are immobilized in stationary phases for liquid chromatography by a variety of techniques, to which we give special attention. We present selected applications to the separation of analytes. Though still few, applications in capillary electromigration are particularly attractive because of the small amounts of liposomes and samples that are required. We demonstrate the promising use of liposomes as carriers and coating materials in capillary electrophoresis with reference to recent applications. We note future directions for the utilization of phospholipids and liposomes in liquid chromatographic and capillary electromigration techniques. [Copyright &y& Elsevier]

The iridoid glycosides, methyl catalpol, asperuloside, verbenalin, cinnamoyl catalpol, catalpol and aucubin, were studied from both larvae and adults of butterfly Melitaea cinxia. Special emphasis in the study was put on finding a correlation between the iridoid glycoside content in butterflies and plants. An optimised partial filling micellar electrokinetic capillary chromatographic–electrospray ionisation mass spectrometric (PF-MECC-ESI-MS) method was employed for the separation and identification of the six iridoid glycosides. In this work, the isolation and determination of catalpol and aucubin from extracts of both larvae and adults of Melitaea cinxia butterflies is demonstrated. The PF-MECC-ESI-MS method, using the [M+Na]+, [M+Li]+ and/or [M+NH4]+ adducts in ESI-MS, was used for quantification of aucubin and catalpol in the insects. In addition, the identification of all analytes was attempted by direct infusion MS/MS analysis. LOQ values for the iridoid glycosides varied between 10 mg/l (for verbenalin) to 50 mg/l (for catalpol and aucubin) corresponding to 0.1% of the samplés dry mass. A correlation was noticed between the concentrations of iridoid glycosides in plants and the concentrations in larvae feeding on them. [ABSTRACT FROM AUTHOR]

Highlights: [•] Silica-based monolith is introduced as a support for liposome immobilization. [•] A new biomimicking chromatographic phase was evaluated by capillary LC and cryo-SEM. [•] Analyte–liposome interactions were investigated. [•] The column permeability depends on the type of liposome dispersion and buffer used. [ABSTRACT FROM AUTHOR]

Abstract: In the case of local anesthetic intoxication, intravenous administration of lipid-based Intralipid dispersion (Fresenius Kabi) can be used for the entrapment of hydrophobic drugs. Our long-term aim is to develop a sensitive, efficient, and non-harmful lipid-based formulation to specifically trap harmful substances. In this study liposome electrokinetic capillary chromatography (LEKC) was used to study the interactions between local anesthetics and Intralipid or liposome dispersions. Intralipid dispersion and extruded liposomes with different concentrations of 1-palmitoyl-2-oleyl-sn-glycerophosphatidylcholine (POPC), phosphatidylglycerol, cardiolipin, cholesterol, oleic acid, and linoleic acid were used as a pseudostationary phase in LEKC and their interactions with lidocaine, prilocaine, and bupivacaine were studied. POPC liposomes containing 1mol% of palmitoyl-2-[12-[(7-nitro-2-1,3-benzoxadiazol-4-yl)amino]dodecanoyl]-sn-glycero-3-phosphocholine as a fluorescent marker were used for the first time in LEKC connected with laser-induced fluorescent detection in order to calculate the retention factor for anesthetics. [Copyright &y& Elsevier]

Toxicity of β -blockers is one of the most common causes of poison-induced cardiogenic shock throughout the world. Therefore, methodologies for in vivo removal of the drugs from the body have been under investigation. Intralipid emulsion (ILE) is a common commercial lipid emulsion used for parenteral nutrition, but it has also been administered to patients suffering from drug toxicities. In this work, a set of β -blockers of different hydrophobicity's (log K D values ranging from 0.16 to 3.8) were investigated. The relative strength of the interactions between these compounds and the ILE was quantitatively assessed by means of binding constants and adsorption constants of the formed β -blocker-ILE complexes. The binding constants were determined by capillary electrokinetic chromatography and the adsorption constants were calculated based on different adsorption isotherms. Expectedly, the binding constants were strongly related to the log K D values of the β -blockers. The binding and adsorption constants also show that less hydrophobic β -blockers interact with ILE, suggesting that this emulsion could be useful for capturing such compounds in cases of their overdoses. Thus, the use of ILE for treatment of toxicities caused by a larger range of β -blockers is worth further investigation. • Interactions of β-blockers with Intralipid emulsion (ILE) were studied by EKC. • In-depth adsorption isotherm analysis was performed on β-blocker-ILE interactions. • Binding constants of ILE-β-blocker complexes were determined. • The more hydrophobic the β-blocker, the stronger are the interactions with ILE. • Hydrophobic β-blockers can potentially be captured by ILE in case of overdoses. [ABSTRACT FROM AUTHOR]

The capability of employing synthesized zwitterionic silica-based monolithic capillary columns (140 mm × 0.1 mm) for separation of highly polar and hydrophilic nucleobases, nucleosides, and nucleotides in hydrophilic interaction chromatography is reported. The suitability of the columns for on-line conjunction with electrospray tandem mass spectrometry was explored. Our results show that the grafted layer of zwitterionic monomer ([2-(methacryloyloxy)ethyl]-dimethyl-(3-sulfopropyl)-ammonium hydroxide or 2-methacryloyloxyethyl phosphorylcholine) on the silica monolithic surface significantly improved the separation selectivity and reproducibility, as compared to the bare silica monolith. The stepwise elution from 90% to 70% of acetonitrile enabled separation of a complex sample mixture containing 21 compounds with a total analysis time less than 40 min. [ABSTRACT FROM AUTHOR]

Abstract: Fatal drug overdoses are a cause for concern all over the world. We present here a lipid-based formulation which has a strong affinity for some common illicit street drugs and can be used in vivo as a lipid ‘sink’. In this study, the in vitro interactions of nine lipophilic drugs and three lipid dispersions were determined by electrokinetic capillary chromatography and fluorescence polarization. Two lipid dispersions, zwitterionic 1-palmitoyl-2-oleyl-sn-glycero-3-phosphocholine (POPC) and an anionic mixture of POPC and 1-palmitoyl-2-oleyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (POPG) were tested and compared with a commercial lipid dispersion Intralipid®, which has been successfully used for resuscitation of patients in cases of anesthetic overdoses. The interactions between dispersions and the drugs were quantified by means of retention factors and distribution constants, which makes the results highly comparable to those obtained from any other formulation of lipids. The results demonstrate a stronger interaction between the drugs and an artificial liposome dispersion than with the commercial Intralipid dispersion. The liposome dispersion composed of POPC and POPG functions as a lipid ‘sink’ for efficient entrapment of various lipophilic drugs. [ABSTRACT FROM AUTHOR]