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Mobile phase additive

Andreas Burgdorf, Inga Güthe, Marko Jovanović, Ekaterina Kutafina, Christian Kohlschein, Jó Ágila Bitsch, Stephan M Jonas
BACKGROUND: Sleep disorders have a prevalence of up to 50% and are commonly diagnosed using polysomnography. However, polysomnography requires trained staff and specific equipment in a laboratory setting, which are expensive and limited resources are available. Mobile and wearable devices such as fitness wristbands can perform limited sleep monitoring but are not evaluated well. Here, the development and evaluation of a mobile application to record and synchronize data from consumer-grade sensors suitable for sleep monitoring is presented and evaluated for data collection capability in a clinical trial...
October 6, 2018: Computers in Biology and Medicine
Bahia Abbas Moussa, Marianne Alphonse Mahrouse, Michael Gamal Fawzy
Combination therapy has a pivotal role in type II diabetes mellitus management in patients unable to maintain normal glycemic level using metformin alone. Addition of linagliptin, dipeptidyl peptidase-IV inhibitor, to metformin improves glycemic control. This study is concerned with the development of an HPLC-MS/MS method for simultaneous quantification of linagliptin and metformin in spiked human plasma. The method was applied to evaluate the potential pharmacokinetic interactions between the cited drugs in healthy volunteers...
October 1, 2018: Journal of Pharmaceutical and Biomedical Analysis
Katarzyna Krzemińska, Mikołaj Dembek, Szymon Bocian
Solvation processes on polar embedded stationary phases were investigated by determination of excess isotherms in binary acetonitrile-water mobile phase. The obtained results indicate competitiveness of acetonitrile and water adsorption on heterogeneous surfaces of chemically bonded stationary phases. The calculation of excess isotherm as a volume of excessively accumulated solvent confirms the competitiveness of solvents' adsorption in qualitative and quantitative meaning. Corresponding excess isotherms of water and acetonitrile are symmetrical versus x-axis...
October 12, 2018: Journal of Separation Science
Lee Chuin Chen, Tsubasa Naito, Satoshi Ninomiya, Kenzo Hiraoka
High-pressure electrospray ionization (HP-ESI) performed under super-atmospheric pressure allows a stable and efficient electrospray of pure aqueous and/or superheated solutions even under a μL min-1 flow rate regime. In this paper, we report the direct coupling of the HP-ESI source to high-temperature liquid chromatography (HT-LC) operated at ≤30 μL min-1 flow rates. In addition to ESI, the ion source functions as a back-pressure regulator to keep the mobile phase in the liquid phase when the column is heated to >100 °C...
October 10, 2018: Analyst
Steven L Raymond, Russell B Hawkins, Julie A Stortz, Tyler J Murphy, Ricardo Ungaro, Marvin L Dirain, Dina C Nacionales, McKenzie K Hollen, Jaimar C Rincon, Shawn D Larson, Scott C Brakenridge, Frederick A Moore, Daniel Irimia, Phil A Efron, Lyle L Moldawer
Sepsis is a common and deadly complication among trauma and surgical patients. Neutrophils must mobilize to the site of infection to initiate an immediate immune response. To quantify the velocity of spontaneous migrating blood neutrophils, we utilized novel microfluidic approaches on whole blood samples from septic and healthy individuals. A prospective study at a level 1 trauma and tertiary care center was performed with peripheral blood samples collected at <12 hours, 4 days, and/or 14 days relative to study initiation...
2018: PloS One
Marta Bożym, Grzegorz Siemiątkowski
This paper determines the impact of the maturation process of composted sewage sludge on the quality of the final product and assesses the stabilization effect. The samples of composted sewage sludge were taken from a wastewater treatment plant located in Pomerania in northern Poland. The sewage sludge was composted in an open windrow composting plant with the addition of straw and wood chips in the turning windrow. The aeration of the sewage sludge mixture was conducted based on two methods. The first phase (intensive degradation phase of 6 to 8 weeks) was characterized by frequently turning; the second phase for maturation used aeration channels (2 to 3 months)...
October 8, 2018: Environmental Science and Pollution Research International
Yunlin Fu, Wenkui Li, Jimmy Flarakos
We report the development, validation and application of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) bioanalytical method for the determination of a recombinant protein drug candidate, NVS001, in human serum. A unique surrogate peptide, IPAETTIYNR (IPA), was identified to distinguish NVS001 from its endogenous counterpart, i.e., the full length and the C-terminal of protein X in LC-MS/MS. The selection of IPA for the LC-MS/MS determination of NVS001 was supported by the absence of peak responses due to endogenous components in the LC-MS/MS chromatograms of the extracted blank human serum samples...
October 2, 2018: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
Tajudheen K Karatt, Ramy Sayed, Jahfar Nalakath, Zubair Perwad, Peter H Albert, K K Abdul Khader
Chirality is one of the most important considerations when controlling doping. The epimeric corticosteroids dexamethasone and betamethasone are significantly potent and long-acting, and they are highly abused in equestrian sports. The scope of this study was to develop a simple and reliable analytical method for simultaneously identifying and separating regularly abused co-eluting corticosteroids in equine urine and plasma. In this paper, we present a simple and rapid method for the chiral separation and identification of epimeric mixtures of dexamethasone and betamethasone using a Thermo Q Exactive high resolution accurate mass spectrometer...
October 5, 2018: Steroids
Daisuke Kato, Kouta Iwasaki, Masahito Yoshino, Tomoaki Yamada, Takanori Nagasaki
Non-stoichiometry related to such an element with high vapor pressure as Mg has been difficult to control, despite its significant influence on the thermoelectric properties of the material. Here, Mg non-stoichiometry and the thermoelectric properties of Mg2-δSi1-xSbx (0 ≤ x ≤ 0.60) are investigated systematically by tuning the Mg partial pressure during annealing. The range of Mg non-stoichiometry Δδ depends on x since the Sb dopant induces Mg vacancies, which are partly filled by Mg atoms in the gas phase according to an equilibrium reaction...
October 17, 2018: Physical Chemistry Chemical Physics: PCCP
Sander Deridder, Wim Smits, Hamza Benkahla, Ken Broeckhoven, Gert Desmet
We report on a numerical study of the thermal conductivity of core-shell particle packed bed columns. Covering a variety of packing structures and a broad range of mobile phase and porous zone conductivities, it was in all cases found that switching to particles with a highly conducting core (e.g., with a gold or copper core instead of a silica core) would produce a much smaller increase of the effective heat conductivity of the bed (keff ) than previously expected in literature. We found maximal increases on the order of some 20-70%, which is much lower than the potential increases up to 2000% assumed in literature...
September 1, 2018: Journal of Chromatography. A
Tomasz Tuzimski, Anna Petruczynik
Ionic liquids (ILs) are a class of unique substances composed purely by cation and anions. Because of the unique properties of ILs (e.g., electric conductivity, low volatility, thermostability, and tenability), their use has attracted considerable interest, including an increasing number of publications on their use in analytical separation techniques. ILs applied as extraction solvents in liquid-liquid extraction methods and promote interactions between the analyte and solvent because of their unique chemical functional groups...
October 5, 2018: Journal of AOAC International
Aneta Hałka-Grysińska, Kamila Skop, Anna Klimek-Turek, Marta Gorzkowska, Tadeusz H Dzido
The new approach to the development of thin-layer chromatograms is presented. For the first time we show flexible mobile phase dosage onto the surface of the adsorbent layer by moving pipette combined with precise syringe pumps. The pipette is driven into movement by computer controlled 3D machine (modified 3D printer mechanism). Delivery of the mobile phase to the adsorbent layer is equal to or lower than that of conventional development. Therefore chromatograms can be developed with optimal mobile phase velocity, adjusted to its absorption rate by the adsorbent layer...
August 4, 2018: Journal of Chromatography. A
Shankar Prinja, Aditi Gupta, Pankaj Bahuguna, Ruby Nimesh
BACKGROUND: The main intervention under ReMiND program consisted of a mobile health application which was used by community health volunteers, called ASHAs, for counselling pregnant women and nursing mothers. This program was implemented in two rural blocks in Uttar Pradesh state of India with an overall aim to increase quality of health care, thereby increasing utilization of maternal & child health services. The aim of the study was to assess annual & unit cost of ReMiND program and its scale up in UP state...
October 3, 2018: BMC Pregnancy and Childbirth
Hong Zhang, Jia-Ming Jiang, Dan Zheng, Ming Yuan, Zhi-Ying Wang, Hong-Mei Zhang, Chang-Wu Zheng, Lian-Bo Xiao, Hong-Xi Xu
Here, time-decoupled comprehensive two-dimensional ultra-high liquid chromatography (UHPLC) coupled with an ion mobility (IM)-high resolution mass spectrometer (HRMS) was established and used to analyze ginsenosides from the main roots of white ginseng (WG) and red ginseng (RG), which enabled the separation of complex samples in four dimensions (2D-LC, ion mobility, and mass spectrometry). The incompatibility of mobile phases, dilution effect, and long analysis time, which are the main shortcomings of traditional comprehensive 2D-LC methods, were largely avoided in this newly established 2D-UHPLC method...
September 21, 2018: Journal of Pharmaceutical and Biomedical Analysis
Prateek Jain, Koushik Shah, Vikas Rishi
Basic leucine zipper (bZIP) transcription factors (TFs) are eukaryote-specific proteins that bind to DNA as a homodimer or heterodimer and regulate gene expression. They are involved in several biological processes in plants; therefore inhibiting bZIP-DNA binding activity by targeting protein-protein interface is an attractive proposition with aspects of both basic and applied biology. Here, we describe the equilibrium and kinetic interactions studies of a designed peptide inhibitor A-ZIP53 and its four variants with the bZIP53 protein, a key regulator of seed maturation phase and stress response in Arabidopsis...
September 29, 2018: Biochimica et biophysica acta. Proteins and proteomics
Wilbert McClay
In Phase I, we collected data on five subjects yielding over 90% positive performance in Magnetoencephalographic (MEG) mid-and post-movement activity. In addition, a driver was developed that substituted the actions of the Brain Computer Interface (BCI) as mouse button presses for real-time use in visual simulations. The process was interfaced to a flight visualization demonstration utilizing left or right brainwave thought movement, the user experiences, the aircraft turning in the chosen direction, or on iOS Mobile Warfighter Videogame application...
September 28, 2018: Diseases (Basel)
David Thornton, Linda Barton, Leo Hsu
We developed an automated countercurrent chromatography (CCC) process to isolate anthocyanins from black currant extract utilizing a solvent system of methyl-t-butyl ether, n-butanol, acetonitrile and water with pH adjusted by addition of trifluoroacetic acid in normal phase mode. The process has excellent repeatability as indicated by the high purity of isolated products (90% or better) and the low retention time variability (<10% RSD overall and <5% RSD at constant mass loading). In addition, we determined solvent system ratios to facilitate independent preparation of stationary and mobile phases which enabled us to reduce solvent waste by 70%...
September 14, 2018: Journal of Chromatography. A
Ya-Nan Zhang, Hong Yu, Ya-Jie Ma, Ge Cui
An analytical method for the simultaneous determination of iodide and iodate by reversed phase liquid chromatography with ultraviolet detection using imidazolium ionic liquids as mobile phase additives was developed in this paper. Imidazolium ionic liquids, pyridinium ionic liquids, and common ion pair reagent tetrabutylammonium hydroxide as mobile phase additives were compared. The results indicated that imidazolium ionic liquids as the mobile phase additives were better than any tetrabutylammonium hydroxide or pyridinium ionic liquids...
September 28, 2018: Analytical and Bioanalytical Chemistry
Cláudia D Tormena, Gustavo G Marcheafave, Miroslava Rakocevic, Roy E Bruns, Ieda S Scarminio
The first metabolic study of the impact of elevated CO2 (590 µL CO2 L-1 ) levels on the leaves and buds of Coffea arabica L. plants is reported. A novel sequential statistical mixture design strategy allowed optimization of both the extraction and mobile phase solvent systems to increase differences detected in metabolites of Coffea arabica L. plants and buds. Factor analysis showed that the 227 and 273 nm bands of the 1:1:1 ternary ethyl ether - dichloromethane - methanol mixture spectra resulted in discrimination of elevated CO2 extract samples from those obtained from leaves grown in a current level CO2 atmosphere (390 µL CO2 L-1 ) of leaf sample extracts...
January 1, 2019: Talanta
Helena Martin-Gómez, Fernando Albericio, Judit Tulla-Puche
The chemical synthesis of a bicycle inspired by the natural lasso peptide sungsanpin using a combination of solid-phase and in-solution chemistries is described. The bicyclic-derived topoisomer was designed introducing a covalent linkage between the ring and the loop, which allowed the tying of these two parts of the peptide rendering the bicyclic structure. Several structural techniques, such as MS fragmentation, ion-mobility and NMR were used to characterize the bicycle. Ion-mobility spectroscopy studies revealed that it showed lasso-like behavior...
September 26, 2018: Chemistry: a European Journal
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