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Mobile phase additive

Li-Xia Liu, Yuan Zhang, Yu Zhou, Guo-Hui Li, Guang-Jian Yang, Xue-Song Feng
Recently, supercritical fluid chromatography (SFC) has attracted considerable attention for their application in food analysis. The use of supercritical CO2 (SC-CO2 ), as a mobile phase for SFC, with its low viscosity and high molecular diffusiveness, results in shorter analysis time and lower consumption of organic solvents as compared to high-performance liquid chromatography (HPLC). In addition, with recent improvements in its detection system, SFC has shown satisfactory selectivity and sensitivity. Thus, although the composition of food is complex, SFC remains a powerful tool in food analysis with some simple sample pretreatment techniques, such as liquid-liquid extraction, solid-phase extraction, and QuEChERS...
March 22, 2019: Critical Reviews in Analytical Chemistry
Nadia Martínez-Villegas, Margaret Suárez Muñoz, Patricia González-Hernández, Clara Melián Rodríguez, Josiel Barrios Cossio, Rebeca Hernández Díaz, Juan R Fagundo Castillo, Alina Gelen Rudnikas, Cristina Díaz López, Aurora Pérez-Gramatges, Oscar Díaz Rizo
Santa Lucía peloid is a sediment used in pelotherapy in Cuban primary health care services. Therefore, in addition to physicochemical regulated parameters, other analyses are required to complement their physicochemical characterization and understand potential element mobility, radiological risk, and toxicity as well as likely bioactive compounds present in Santa Lucía peloid. For these purposes, inorganic and organic elements and compounds were considered to evaluate Santa Lucía peloid's quality. This was accomplished through an integral approach that included (1) determination of physicochemical parameters (pH, electrical conductivity, oxidation-reduction potential, temperature, dissolved oxygen, elemental C, H, and N analyses, organic matter, and hexane removable substances content); (2) determination of total concentration of elements with biological and toxicological importance (i...
March 21, 2019: Environmental Science and Pollution Research International
Liai Lan, Shengyuan Wu, Yu Shidan, Jingjing Jiang, Honghong Chen, Yuefen Lou, Guorong Fan
It is usually somewhat difficult to analyze the metal chelators, especially in complex biological matrix, because of the interference of metal ions in both the matrix and analyzing system. In this study, an innovative and simple bioanalytical method was established and validated for the quantification of a newly developed uranium chelator catechol-3, 6-bis (methyleiminodiacetic acid) (CBMIDA) in beagle dog plasma. Different analytical columns and mobile phase were tested for effective chromatography resolution and sensitive and reproducible response of CBMIDA and the internal standard...
March 8, 2019: Journal of Chromatography. A
Hanliu Wang, Joseph Eschweiler, Weidong Cui, Hao Zhang, Carl Frieden, Brandon T Ruotolo, Michael L Gross
Apolipoprotein E (apoE) is an essential protein in lipid and cholesterol metabolism. Although the three common isoforms in humans differ only at two sites, their consequences in Alzheimer's disease (AD) are dramatically different: only the ε4 allele is a major genetic risk factor for late-onset Alzheimer's disease. The isoforms exist as a mixture of oligomers, primarily tetramer, at low μM concentrations in a lipid-free environment. This self-association is involved in equilibrium with the lipid-free state, and the oligomerization interface overlaps with the lipid-binding region...
March 18, 2019: Journal of the American Society for Mass Spectrometry
Lucas Maciel da Costa, Heitor Oliveira de Almeida Leite, Nájla Mohamad Kassab, Anil Kumar Singh
Antihistamines are widely used to alleviate the symptoms caused by allergic reactions. Most of these drugs have zwitteriónicas and/or amphoteric characteristics, which confer additional analytical challenges. This work aimed to develop a single eco-friendly and efficient chromatographic methods for analysis of seven antihistamines, namely, azelastine HCl, desloratadine, ebastine, fexofenadine HCl, ketotifen, loratadine, and olopatadine HCl. The separations were obtained using RP C-18 LUNA (150x4.6mm, 5  μ m) column...
2019: International Journal of Analytical Chemistry
Wei Li, Yi Wu, Mali Wan, Yang Chu, Xiangyang Wang, Shuming Li, Zuhui Liu, Xue Chen, Navaneethakrishnan Polachi, Shuiping Zhou, He Sun
As one of the main constituents of Compound Danshen Dripping Pills (CDDP), Panax notoginseng (PN) plays a pivotal role in the treatment of cardiovascular diseases. Numerous researches have proved that the dammarane type saponins including notoginsenoside R1 (NR1), ginsenoside Rg1 (GRg1) and ginsenoside Rb1 (GRb1) are the main bioactive components of PN in CDDP. An efficient, realiable and sensitive liquid chromatography tandem-mass spectrometry (LC-MS/MS) analysis method for simultaneously detecting NR1, GRg1 and GRb1 in human plasma was established and applied to the pharmacokinetics study of the three PN saponins after oral administration of CDDP...
March 5, 2019: Journal of Pharmaceutical and Biomedical Analysis
Sophia Barhdadi, Bart Desmedt, Patricia Courselle, Vera Rogiers, Tamara Vanhaecke, Eric Deconinck
The electronic cigarette (e-cigarette) has emerged as a popular alternative to the traditional hazardous tobacco cigarette. The substantial increase in e-cigarette use also urgently calls for controlling the quality of e-cigarette refill liquid products (e-liquids). Currently, the most important quality indicator of e-liquid products is the quantification of nicotine and its related impurities. Although different methods have been published to measure nicotine and impurity levels, the majority of them use a targeted LC-MS/MS approach...
March 2, 2019: Journal of Pharmaceutical and Biomedical Analysis
Dora Koller, Pablo Zubiaur, Miriam Saiz-Rodríguez, Francisco Abad-Santos, Aneta Wojnicz
A simple and sensitive liquid chromatography-tandem mass spectrometry method was developed and validated in human plasma for the simultaneous determination of aripiprazole (ARI) and its metabolite dehydro-aripiprazole (DARI); olanzapine (OLA), risperidone (RIS), paliperidone (PAL), quetiapine (QUE), clozapine (CLO) and caffeine (CAF). CAF is included to the method because it can have an influence on drug metabolism due to competitive inhibition. The above mentioned compounds and their isotope-labeled internal standards were extracted from 200 µL human plasma samples by both, effective phospholipids-eliminating three-step microelution-solid-phase extraction (µ-SPE) and protein precipitation (PPT) for comparison...
June 1, 2019: Talanta
Eran Hershko, Lucien E Weiss, Tomer Michaeli, Yoav Shechtman
Deep learning has become an extremely effective tool for image classification and image restoration problems. Here, we apply deep learning to microscopy and demonstrate how neural networks can exploit the chromatic dependence of the point-spread function to classify the colors of single emitters imaged on a grayscale camera. While existing localization microscopy methods for spectral classification require additional optical elements in the emission path, e.g., spectral filters, prisms, or phase masks, our neural net correctly identifies static and mobile emitters with high efficiency using a standard, unmodified single-channel configuration...
March 4, 2019: Optics Express
Bhagya N, Chandrashekar K R
Reverse phase column chromatography technique was employed to isolate tetrandrine from methanolic extract of Cyclea peltata roots. Tetrandrine was efficiently isolated using 0.02% aqueous diethylamine and methanol (25:75, v/v) as mobile phase with a purity of 98.63%. Compound characterisation was achieved using high-performance liquid chromatography coupled with electrospray ionization mass spectrometry and other spectroscopic methods. In addition, quantification of tetrandrine and validation of the method was carried out following International Conference on Harmonisation guidelines...
March 15, 2019: Natural Product Research
Bahia A Moussa, Nadia F Youssef, Ehab F Elkady, Marwa F Mohamed
Economic and enantioselective synchronous fluorescence spectroscopy and high-performance thin-layer chromatography methods have been developed and validated as per ICH guidelines for the separation of zopiclone enantiomers using L-(+)-tartaric acid as a chiral selector, followed by determination of the chiral-switching eszopiclone. Synchronous fluorescence spectroscopy was successfully applied for chiral recognition of R & S enantiomers of zopiclone at ∆λ = 110 nm based on creating of diastereomeric complexes with 0...
March 12, 2019: Chirality
Christian Becker, Maik A Jochmann, Torsten C Schmidt
In the past, the main focus of flame ionization detector (FID) response studies was set on investigations of gas chromatography (GC) relevant analytes such as aliphatic hydrocarbons and selected functional groups. Only a few data are available for liquid chromatography (LC)/FID responses. Within this research paper, we present the FID response factors for a LC/FID system with an aqueous eluent as mobile phase. The study focus on the most common analytes of LC/FID studies in the past as well as several compounds that are not directly GC compatible because of their polarity...
March 12, 2019: Analytical and Bioanalytical Chemistry
Mariia Selivanova, Ching-Heng Chuang, Blandine Billet, Aleena Malik, Peng Xiang, Eric Landry, Yu-Cheng Chiu, Simon Rondeau-Gagné
A new strategy for influencing the solid-state morphology of conjugated polymers was developed through physical blending with a low molecular weight branched polyethylene. This non-toxic and low boiling point additive was blended with a high charge mobility DPP-based conjugated polymer and a detailed investigation of the new blended materials was performed by various characterization tools, including X-ray diffraction, UV-Vis spectroscopy and atomic force microscopy. Interestingly, the branched additive was shown to reduce the crystallinity of the conjugated polymer, while promoting aggregation and phase separation in the solid-state...
March 11, 2019: ACS Applied Materials & Interfaces
Chiara Giorio, Claudio Bortolini, Ivan Kourtchev, Andrea Tapparo, Sara Bogialli, Markus Kalberer
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous atmospheric pollutants of high concern for public health. In the atmosphere they undergo oxidation, mainly through reactions with ·OH and NOx to produce nitro- and oxygenated (oxy-) derivatives. In this study, we developed a new method for the detection of particle-bound PAHs, nitro-PAHs and oxy-PAHs using direct infusion into an atmospheric pressure photoionisation high-resolution mass spectrometer (APPI-HRMS). Method optimisation was done by testing different source temperatures, gas flow rates, mobile phases and dopants...
February 27, 2019: Chemosphere
Marek Dziadosz
In this work the examination of analyte adduct formation by the application of both sodium acetate and lithium acetate was performed with salicylic acid used as a model drug. Additionally, on the basis of combined acetate salt based multiple analyte adduct ions it was aimed to investigate the generation of different analyte precursor ions and their application in signal separated quantification with liquid chromatography-tandem mass spectrometry. Adduct identification experiments were performed by infusion experiments and resulted in an optimised detection of analyte adduct ions with lithium acetate, sodium acetate and combined lithium acetate/sodium acetate...
February 22, 2019: Forensic Science International
Bryce E Ackermann, Galia T Debelouchina
Heterochromatin protein 1α (HP1α) undergoes liquid-liquid phase separation (LLPS) and forms liquid droplets and gels in vitro, properties that also appear to be central to its biological function in heterochromatin compaction and regulation. Here we use solid-state NMR spectroscopy to track the conformational dynamics of phosphorylated HP1α during its transformation from the liquid to the gel state. Using experiments designed to probe distinct dynamic modes, we identify regions with varying mobilities within HP1α molecules and show that specific serine residues uniquely contribute to gel formation...
March 7, 2019: Angewandte Chemie
Francesco Locatelli, Lucia Del Vecchio
Prolyl-hydroxylase (PHD) inhibitors (PHD-I) are the most appealing drugs undergoing clinical development for the treatment of anaemia in patients with chronic kidney disease. PHD inhibition mimics the exposure of the body to hypoxia and activates the hypoxia-inducible factor system. Among many other pathways, this activation promotes the production of endogenous erythropoietin (EPO) and the absorption and mobilization of iron. PHD-I are given orally and, differing from erythropoiesis-stimulating agents (ESAs), they correct and maintain haemoglobin levels by stimulating endogenous EPO production...
March 7, 2019: Nephrology, Dialysis, Transplantation
Ling He, Xiaoqian Shi, S W Seto, C Dennis, Heng Wang, Sheng Zhang, Weidong Chen, Jian Wang
Naoluoxintong decoction (NLXTD) is a traditional Chinese formula which has been used for the management of ischemic stroke in China for two hundred years. In this study, we developed a comprehensive and reliable analytical method to qualitatively analyze the components in NLXTD. This novel method was based on three-dimensional ultra-fast high performance liquid chromatography coupled with diode array detector (3D-UPLC-DAD) with an additional component validation method via incorporation of the mixture standard compounds during the verification step...
February 22, 2019: Journal of Pharmaceutical and Biomedical Analysis
Jiannan Sun, Shiwei Yang, Heyong Cheng, Yuanchao Wang, Jinhua Liu
Further development of capillary electrochromatography (CEC) is to some extent restricted by column technology. Packed capillary columns are most commonly used in CEC because of higher sample capacity and higher sensitivity than open tubular columns, and better reproducibility and uniformity than monolithic columns. Fritting is the core component for the fabrication of packed capillary columns. Therefore various fritting technologies attract continuous attention from analytical community. A convenient fritting method was developed in this study...
February 22, 2019: Journal of Chromatography. A
Hosam Eldin Dahshan, Mohamed A Helal, Samia M Mostafa, Mohamed Saleh Elgawish
The introduction of sildenafil (SDF) to treat erectile dysfunction has solved a widespread condition with negative on the quality of life. Recently, the co-administration of tramadol (TMD) with SDF to manage premature ejaculation has illegally increased and thus drug-drug interaction studies of these drugs became of great importance. Although certain biological functions have been altered upon co-administration of the two drugs, methods for their determination in vivo to understand their interactions have yet to be published...
February 19, 2019: Journal of Pharmaceutical and Biomedical Analysis
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