linear polarization resistance
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Combined effects of temperature and mobile phase on the reversed phase chromatographic behavior of alkylbenzenes and simple substituted benzenes were investigated on a Blaze C8 polydentate silica-based column, showing improved resistance against hydrolytic breakdown at temperatures higher than 60 degrees C, in comparison to silica-based stationary phases with single attachment sites. For better insight into the retention mechanism on polydentate columns, we determined the enthalpy and entropy of the transfer of the test compounds from the mobile to the stationary phase. The enthalpic contribution dominated the retention at 80% or lower concentrations of methanol in the mobile phase. Entropic effects are more significant in 90% methanol and in acetonitrile-water mobile phases. Anomalies in the effects of mobile phase on the enthalpy of retention of benzene, methylbenzene and polar benzene derivatives were observed, in comparison to regular change in enthalpy and entropy of adsorption with changing concentration of organic solvent and the alkyl length for higher alkylbenzenes. The temperature and the mobile phase effects on the retention are practically independent of each other and--to first approximation--can be described by a simple model equation, which can be used for optimization of separation conditions.
- MeSH
- acetonitrily chemie MeSH
- benzenové deriváty chemie MeSH
- chemické modely MeSH
- hydrofobní a hydrofilní interakce MeSH
- lineární modely MeSH
- methanol chemie MeSH
- reprodukovatelnost výsledků MeSH
- teplota MeSH
- termodynamika MeSH
- vysokoúčinná kapalinová chromatografie metody MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
A new type of high performance liquid chromatography (HPLC) stationary phase was prepared, and its chromatographic properties were evaluated. The sorbent was composed of metallacarborane covalently bound to silica. Because of the chemical structure of the immobilized metallacarborane, the synthesized stationary phase was able to interact with nonpolar analytes via hydrophobic interactions. The chromatographic behavior of several low-molecular-weight hydrocarbons on the sorbent under typical reversed-phase conditions was compared with octadecyl-, sulfo phenyl- and aminopropyl-modified silica stationary phases. Moreover, as a consequence of the synthetic protocol employed, the immobilization of the metallacarborane led to the development of a zwitterionic chemically bonded phase, which demonstrated excellent resistance to "phase collapse" in a 100% aqueous environment. Finally, preliminary experiments indicated that the new stationary phase has the potential for utilization in hydrophilic interaction chromatography (HILIC) mode for the separation of polar compounds.
- MeSH
- acetonitrily chemie MeSH
- benzenové deriváty chemie MeSH
- borany chemie MeSH
- chromatografie s reverzní fází MeSH
- hydrofobní a hydrofilní interakce MeSH
- kobalt chemie MeSH
- lineární modely MeSH
- oxid křemičitý chemie MeSH
- Ramanova spektroskopie MeSH
- reprodukovatelnost výsledků MeSH
- vysokoúčinná kapalinová chromatografie přístrojové vybavení metody MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
... thermometer 60 -- 3.10.3 Calorimetric thermometer 61 -- 3.10.4 Thermocouple 61 -- 3.10.5 Electrical resistance ... ... 6.3.1 Rayleigh scattering 91 -- 6.3.2 Raman scattering 92 -- 6.4 Absorption of light 92 -- 6.5 Polarization ... ... -- 8.2 Ionizing radiation and it sources 119 -- 8.2.1 Particles with positive charge 119 -- 8.2.2 Linear ...
Učební texty Univerzity Karlovy v Praze
Third edition 132 stran : ilustrace ; 30 cm
- Konspekt
- Biochemie. Molekulární biologie. Biofyzika
- Učební osnovy. Vyučovací předměty. Učebnice
- NLK Obory
- fyzika, biofyzika
- NLK Publikační typ
- učebnice vysokých škol
... thermometer 60 -- 3.10.3 Calorimetric thermometer 61 -- 3.10.4 Thermocouple 61 -- 3.10.5 Electrical resistance ... ... 6.3.1 Rayleigh scattering 91 -- 6.3.2 Raman scattering 92 -- 6.4 Absorption of light 92 -- 6.5 Polarization ... ... 119 -- 8.2 Ionizing radiation and it sources 1198.2.1 Particles with positive charge 119 -- 8.2.2 Linear ...
Učební texty Univerzity Karlovy v Praze
2nd ed. 132 s. : il. ; 30 cm
- MeSH
- biofyzika záření MeSH
- biofyzika MeSH
- elektrofyziologie MeSH
- molekulární struktura MeSH
- spektrální analýza MeSH
- termodynamika MeSH
- Publikační typ
- učebnice MeSH
- Konspekt
- Biochemie. Molekulární biologie. Biofyzika
- NLK Obory
- fyzika, biofyzika
Zanamivir (Za) is a highly polar and hydrophilic antiviral drug used for the treatment of influenza A viruses. Za has been detected in rivers of Japan and it's environmental occurrence has the risk of inducing antiviral resistant avian influenza viruses. In this study, a rapid automated online solid phase extraction liquid chromatography method using bonded zwitterionic stationary phases and tandem mass spectrometry (SPE/LC-MS/MS) for trace analysis of Za was developed. Furthermore, an internal standard (IS) calibration method capable of quantifying Za in Milli-Q, surface water, sewage effluent and sewage influent was evaluated. Optimum pre-extraction sample composition was found to be 95/5 v/v acetonitrile/water sample and 1% formic acid. The developed method showed acceptable linearities (r(2)≥0.994), filtration recovery (≥91%), and intra-day precisions (RSD≤16%), and acceptable and environmentally relevant LOQs (≤20ngL(-1)). Storage tests showed no significant losses of Za during 20 days and +4/-20°C (≤12%) with the exception of influent samples, which should be kept at -20°C to avoid significant Za losses. The applicability of the method was demonstrated in a study on phototransformation of Za in unfiltered and filtered surface water during 28 days of artificial UV irradiation exposure. No significant (≤12%) phototransformation was found in surface water after 28 days suggesting a relatively high photostability of Za and that Za should be of environmental concern.
- MeSH
- acetonitrily chemie MeSH
- antivirové látky analýza chemie MeSH
- chemické látky znečišťující vodu analýza chemie MeSH
- chromatografie kapalinová metody MeSH
- extrakce na pevné fázi metody MeSH
- formiáty chemie MeSH
- hydrofobní a hydrofilní interakce MeSH
- on-line systémy MeSH
- řeky chemie MeSH
- tandemová hmotnostní spektrometrie metody MeSH
- ultrafialové záření MeSH
- zanamivir analýza chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Japonsko MeSH
... Linear amplifiers 80 -- Triode voltage amplifier 80 -- 2. Wide band amplifiers 81 -- 3. ... ... -- Cathode follower output time constant -- Cathode follower input resistance -- Cathode follower input ... ... microelectrodes 214 -- Electric characteristics of microelectrodes and their measurement 215 -- Resistance ... ... Electric potentials of tissues 285 a) Polarity of frog skin 285 b) Positive demarcation potential of ... ... Electric polarity of the animal organism 300 -- Electric phenomena of early embryogenesis in the chick ...
3. rev. ed. 824 s. : il.
... DNA 32 Noncanonical DNA Structures 41 -- 2.4 HIGHER-ORDER STRUCTURE OF DNA 48 Genomic DNA May Be Linear ... ... and Proteins Can Be Separated on the Basis of their Differences in pi 85 Amino Acid Side Chains Have Polar ... ... Elongation 141 DNA Polymerases 142 -- Separating Parental Strands: The Replication Fork 144 Solving the Polarity ... ... The Replisome 150 Termination of Replication in Circular Genomes 150 Termination of Replication in Linear ... ... Recombinant DNA Molecules in a Gene Library 266 Selection of Transformed Bacteria by Loss of Antibiotic Resistance ...
7th ed. xxxii, 1204 s. : il. ; 29 cm
... Loss, 14 X-Ray Production, 14 -- Characteristic X-Rays and Auger Electrons, 16 Stopping Power and Linear ... ... 38 Ion Recombination Losses, 38 Correction for Atmospheric Conditions, 38 Chamber Stem Effect, 39 Polarity ... ... 45 Genetic Structures, 45 Cells and Biological Structures, 45 Composite Detectors and Arrays, 45 Linear ... ... Mills -- Introduction, 122 -- The Medical Linear Accelerator, 122 Linear Accelerator Layout and Components ... ... , 123 X-Ray Beam, 124 Electron Beam, 126 -- Linear Accelerator Control Systems, 127 Nonstandard Linear ...
Eighth edition xxiii, 615 stran : ilustrace, tabulky ; 28 cm
- MeSH
- nádory radioterapie MeSH
- nukleární lékařství metody MeSH
- radioterapie metody MeSH
- Publikační typ
- učebnice MeSH
- Konspekt
- Učební osnovy. Vyučovací předměty. Učebnice
- Lékařské vědy. Lékařství
- NLK Obory
- radiologie, nukleární medicína a zobrazovací metody
- onkologie
- NLK Publikační typ
- kolektivní monografie
... Nucleotides Are Used to Build -- Nucleic Acids 44 -- Monosaccharides Joined by Glycosidic Bonds -- Form Linear ... ... FUNCTION 63 -- QQ[ Hierarchical Structure of Proteins 64 -- The Primary Structure of a Protein Is Its Linear ... ... Structure of Nucleic Acids 113 -- A Nucleic Acid Strand Is a Linear Polymer with -- End-to-End Directionality ... ... -- The Single Photosystem of Purple Bacteria -- Generates a Proton-Motive Force but No 02 517 -- Linear ... ... 826 -- Proteoglycans and Their Constituent GAGs Play -- Diverse Roles in the ECM 827 -- Hyaluronan Resists ...
6th ed. xxxvii, 1150 s. : il., tab. ; 29 cm
- MeSH
- biologie buňky MeSH
- molekulární biologie MeSH
- Publikační typ
- monografie MeSH
- Konspekt
- Biochemie. Molekulární biologie. Biofyzika
- NLK Obory
- biologie
- cytologie, klinická cytologie
... Siegelbaum -- Input Resistance Determines the Magnitude of Passive Changes in Membrane Potential 140 ... ... Membrane Capacitance Prolongs the Time Course of Electrical Signals 142 -- Membrane and Axoplasmic Resistance ... ... by Metabotropic Receptors Share a Common Molecular Logic 230 -- The Cyclic AMP Pathway Involves a Polar ... ... Complex Movements That Serve Protective and Postural Functions 715 -- The Stretch Reflex Acts to Resist ... ... Transmits Sensory Information From the Vestibular Organs 803 -- The Utricle and the Saccule Detect Linear ...
4th ed. xxxiii, 1414 s. : il., tab., grafy ; 30 cm
- MeSH
- chování MeSH
- molekulární biologie MeSH
- nemoci nervového systému MeSH
- nervový systém MeSH
- neurochemie MeSH
- neurofyziologie MeSH
- neurony MeSH
- neurovědy MeSH
- Publikační typ
- monografie MeSH
- Konspekt
- Fyziologie člověka a srovnávací fyziologie
- NLK Obory
- neurovědy
- biologie
