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Journal of Chromatography. A

Heike Bittersohl, Björn Schniedewind, Uwe Christians, Peter B Luppa
Therapeutic drug monitoring (TDM) of the immunosuppressive drug tacrolimus is essential to avoid side effects and rejection of the allograft after transplantation. In the blood circulation, tacrolimus is largely located inside erythrocytes or bound to plasma proteins and less than 0.1% is protein-unbound (free). One basic principle of clinical pharmacology is that only free drug is pharmacologically active and monitoring this portion has the potential to better reflect the drug effect than conventional measurements of total tacrolimus in whole blood...
March 7, 2018: Journal of Chromatography. A
F Vela-Soria, L M Iribarne-Durán, V Mustieles, I Jiménez-Díaz, M F Fernández, N Olea
Concerns are growing about human exposure to endocrine disrupting chemicals (EDCs), especially during developmental stages. Parabens (PBs) and ultraviolet filters (UVFs) are prevalent EDCs widely used as additives in cosmetics and personal care products (PCPs). The objective of this study was to develop a method to determine four PBs and ten UVFs in human milk using QuEChERS treatment and ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Multivariate strategies were applied to optimize experimental parameters...
March 6, 2018: Journal of Chromatography. A
Caifeng Xiong, Jie Yuan, Zhiying Wang, Siyao Wang, Chenchen Yuan, Lili Wang
In this work, 2-methacryloyloxyethyl phosphorylcholine (MPC) was used as a ligand to prepare a novel mixed-mode chromatography (MMC) stationary phase by the thiol-ene click reaction onto silica (MPC-silica). It was found that this MPC-silica showed the retention characteristics of hydrophilic interaction chromatography (HILIC) and weak cation exchange chromatography (WCX) under suitable mobile phase conditions. In detail, acidic and basic hydrophilic compounds and puerarin from pueraria were separated quickly with HILIC mode...
March 6, 2018: Journal of Chromatography. A
Justyna Aszyk, Paweł Kubica, Mateusz Kacper Woźniak, Jacek Namieśnik, Andrzej Wasik, Agata Kot-Wasik
Many flavour compounds that are present in e-liquids for e-cigarettes are responsible for specific tastes and smoking sensations for users. Data concerning content and specific types of flavours is often limited and unknown to users. The aim of the research was to define and compare flavour profiles of e-liquids with the same group taste from different manufacturers. Gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) was used to separate and identify 90 popular compounds (98, including isomers) of interest...
March 5, 2018: Journal of Chromatography. A
Chun-Hsien Chen, Yu-Ying Chao, Yi-Hui Lin, Yen-Ling Chen
The on-line preconcentration technique of field-enhanced sample stacking and sweeping (FESS-sweeping) are combined with dispersive liquid-liquid microextraction (DLLME) to monitor the concentrations of finasteride, which is used in the treatment of androgenetic alopecia, and its metabolite, finasteride carboxylic acid (M3), in urine samples. DLLME is used to concentrate and eliminate the interferences of urine samples and uses chloroform as an extracting solvent and acetonitrile as a disperser solvent. A high conductivity buffer (HCB) was introduced into capillary and then sample plug (90...
March 5, 2018: Journal of Chromatography. A
Steffen Großhans, Matthias Rüdt, Adrian Sanden, Nina Brestrich, Josefine Morgenstern, Stefan Heissler, Jürgen Hubbuch
Fourier-transform infrared spectroscopy (FTIR) is a well-established spectroscopic method in the analysis of small molecules and protein secondary structure. However, FTIR is not commonly applied for in-line monitoring of protein chromatography. Here, the potential of in-line FTIR as a process analytical technology (PAT) in downstream processing was investigated in three case studies addressing the limits of currently applied spectroscopic PAT methods. A first case study exploited the secondary structural differences of monoclonal antibodies (mAbs) and lysozyme to selectively quantify the two proteins with partial least squares regression (PLS) giving root mean square errors of cross validation (RMSECV) of 2...
March 5, 2018: Journal of Chromatography. A
María Jesús Martínez Bueno, Francisco José Díaz-Galiano, Łukasz Rajski, Víctor Cutillas, Amadeo R Fernández-Alba
In the last decade, the consumption trend of organic food has increased dramatically worldwide. However, the lack of reliable chemical markers to discriminate between organic and conventional products makes this market susceptible to food fraud in products labeled as "organic". Metabolomic fingerprinting approach has been demonstrated as the best option for a full characterization of metabolome occurring in plants, since their pattern may reflect the impact of both endogenous and exogenous factors...
March 3, 2018: Journal of Chromatography. A
Ariel Fontana, Isaac Rodríguez, Rafael Cela
The suitability of dispersive liquid-liquid microextraction (DLLME) and gas chromatography accurate mass spectrometry (GC-MS), based on a time-of-flight (TOF) MS analyzer and using electron ionization (EI), for the characterization of volatile and semi-volatile profiles of grape marc distillates (grappa) are evaluated. DLLME conditions are optimized with a selection of compounds, from different chemical families, present in the distillate spirit. Under final working conditions, 2.5 mL of sample and 0.5 mL of organic solvents are consumed in the sample preparation process...
March 3, 2018: Journal of Chromatography. A
Juan Wang, Yali Shi, Yaqi Cai
In the present study, a highly selective fluorous affinity-based dispersive liquid-liquid microextraction (DLLME) technique was developed for the extraction and analysis of per- and polyfluoroalkyl substances (PFASs) followed by high performance liquid chromatography tandem-mass spectrometry. Perfluoro-tert-butanol with multiple C-F bonds was chosen as the extraction solvent, which was injected into the aqueous samples with a dispersive solvent (acetonitrile) in a 120:800 (μL, v/v) mixture for PFASs enrichment...
March 1, 2018: Journal of Chromatography. A
Xiao-Tong Luo, Bao-Dong Cai, Lei Yu, Jun Ding, Yu-Qi Feng
Brassinosteroids (BRs) are regarded as the sixth plant hormone that is widely distributed in the plant kingdom. Sensitive quantification of BRs will be greatly benefit to illuminate the detail mechanisms about how BRs play crucial role in plant developmental processes such as cell division, cell expansion, cytodifferentiation, seed germination, vegetative growth and resisting biological or abiotic stress. In the current study, we developed a method for rapid and sensitive determination of endogenous BRs in plant tissues by combining LC-MS and a novel sample preparation strategy, in which the plant tissue extract was supplied to solid phase boronate affinity labeling and extraction, followed by desorption and salt-induced phase transition extraction for further purification...
February 28, 2018: Journal of Chromatography. A
Aitor Sorribes-Soriano, Francesc Albert Esteve-Turrillas, Sergio Armenta, Ana Montoya, José Manuel Herrero-Martínez, Miguel de la Guardia
Magnetic molecularly imprinted polymers (MMIPs) were prepared for cocaine recognition by bulk polymerization in the presence of magnetic nanoparticles (MNPs). Two reagents (polyethylene glycol (PEG) and 3-(trimethoxysilyl)propyl methacrylate (V)) were used for MNPs modification. MMIPs were characterized and compared in terms of loading capacity, reusability, accuracy and precision for the extraction of cocaine from saliva samples. It was observed that V-MMIPs gave higher physical stability than PEG-MMIPs. Thus, V-MMIP were used for the analysis of cocaine users saliva...
February 27, 2018: Journal of Chromatography. A
Jordan Stubleski, Petr Kukucka, Samira Salihovic, P Monica Lind, Lars Lind, Anna Kärrman
The objective of this study was to develop and validate a 96-well plate solid phase extraction method for analysis of 23 lipophilic persistent organic pollutants (POPs) in low-volume plasma and serum samples which is applicable for biomonitoring and epidemiological studies. The analysis of selected markers for internal exposure: 16 polychlorinated biphenyls (PCBs), 5 organochlorine pesticides (OCPs), octachlorinated dibenzo-p-dioxin (OCDD), and polybrominated diphenylether 47 (BDE 47) was evaluated by comparing two SPE sorbents and GC-HRMS or GC-MS/MS detection...
February 27, 2018: Journal of Chromatography. A
Lianyun Lin, Chen Liu, Bidhan Chandra Nayak, Weiyi He, Minsheng You, Zhiguang Yuchi
Calmodulin (CaM) is a Ca2+ -binding protein that plays an important role in cellular Ca2+ -signaling. CaM interacts with diverse downstream target proteins and regulates their functions in a Ca2+ -dependent manner. CaM changes its conformation and hydrophobicity upon [Ca2+ ] change and consequently changes its interaction with CaM-binding domains from the targets. Based on these special properties of CaM, it was used as an affinity tag to develop a novel purification strategy by using it for two sequential orthogonal purification steps: 1) an affinity purification step, in which CaM-tag interacts with an immobilized CaM-binding domain; and 2) a hydrophobic interaction chromatography step, during which CaM binds to a phenyl sepharose column...
February 27, 2018: Journal of Chromatography. A
Tamar Khatiashvili, Rusudan Kakava, Iza Matarashvili, Hadi Tabani, Chiara Fanali, Alessandro Volonterio, Tivadar Farkas, Bezhan Chankvetadze
The present study reports successful separations of enantiomers of selected chiral sulfoxides with very high separation factor in high-performance liquid chromatography by using chiral columns prepared with the chiral selector cellulose tris(4-chloro-3-methylphenylcarbamate). High separation factors were observed in polar organic, as well as in hydrocarbon-alcohol-type mobile phases. The key structural components of the solute for obtaining high chiral recognition are discussed as well as thermodynamic quantities of analyte adsorption on the chiral stationary phase were determined...
February 26, 2018: Journal of Chromatography. A
Lilla Turiák, Gábor Tóth, Oliver Ozohanics, Ágnes Révész, András Ács, Károly Vékey, Joseph Zaia, László Drahos
A simple, isocratic HPLC method based on HILIC-WAX separation, has been developed for analyzing sulfated disaccharides of glycosaminoglycans (GAGs). To our best knowledge, this is the first successful attempt using this special phase in nano-HPLC-MS analysis. Mass spectrometry was based on negative ionization, improving both sensitivity and specificity. Detection limit for most sulfated disaccharides were approximately 1 fmol; quantitation limits 10 fmol. The method was applied for glycosaminoglycan profiling of tissue samples, using surface digestion protocols...
February 25, 2018: Journal of Chromatography. A
Negin Parham, Homayon Ahmad Panahi, Alireza Feizbakhsh, Elham Moniri
In this present study, poly (N-isopropylacrylamide) as a thermo-sensitive agent was grafted onto magnetic nanoparticles, then ethylenediamine and methylmethacrylate were used to synthesize the first generation of poly amidoamine (PAMAM) dendrimers successively and the process continued alternatively until the ten generations of dendrimers. The synthesized nanocomposite was investigated using Fourier transform infrared spectrometry, thermalgravimetry analysis, X-ray diffractometry, elemental analysis and vibrating-sample magnetometer...
February 24, 2018: Journal of Chromatography. A
Matthew J O'Hara, Nathaniel J Murray, Jennifer C Carter, Samuel S Morrison
Zirconium-89 (89 Zr), produced by the (p, n) reaction from naturally monoisotopic yttrium (nat Y), is a promising positron emitting isotope for immunoPET imaging. Its long half-life of 78.4 h is sufficient for evaluating slow physiological processes. A prototype automated fluidic system, coupled to on-line and in-line detectors, has been constructed to facilitate development of new89 Zr purification methodologies. The highly reproducible reagent delivery platform and near-real time monitoring of column effluents allows for efficient method optimization...
February 24, 2018: Journal of Chromatography. A
Danielle V Polniak, Eric Goodrich, Nicole Hill, Blanca H Lapizco-Encinas
Dielectrophoresis (DEP), the migration of particles due to polarization effects under the influence of a nonuniform electric field, was employed for characterizing the behavior and achieving the separation of larger (diameter >5 μm) microparticles by exploiting differences in electrical charge. Usually, electrophoresis (EP) is the method of choice for separating particles based on differences in electrical charge; however, larger particles, which have low electrophoretic mobilities, cannot be easily separated with EP-based techniques...
February 24, 2018: Journal of Chromatography. A
Patience Sanderson, Morgan Stickney, Franklin E Leach, Qiangwei Xia, Yanlei Yu, Fuming Zhang, Robert J Linhardt, I Jonathan Amster
Reverse polarity capillary zone electrophoresis coupled to negative ion mode mass spectrometry (CZE-MS) is shown to be an effective and sensitive tool for the analysis of glycosaminoglycan mixtures. Covalent modification of the inner wall of the separation capillary with neutral or cationic reagents produces a stable and durable surface that provides reproducible separations. By combining CZE-MS with a cation-coated capillary and a sheath flow interface, a rapid and reliable method has been developed for the analysis of sulfated oligosaccharides from dp4 to dp12...
February 24, 2018: Journal of Chromatography. A
Víctor Cutillas, María Martínez Galera, Łukasz Rajski, Amadeo R Fernández-Alba
Supercritical fluid chromatography coupled to triple quadrupole mass spectrometry has been evaluated for pesticide residues in food. In order to check its advantages and limitations it was developed a method to identify and quantify 164 pesticides in three different matrices (tomato, orange and leek). A carbon dioxide gradient with methanol (containing 1 mM ammonium formate) was used allowing a flow rate of 1.5 mL/min that made the total run time of 12 min without any problem of overpressure. Addition of a post column flow 150 μL/min of Methanol with ammonium formate/formic acid was necessary to improve the ionization...
February 23, 2018: Journal of Chromatography. A
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