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Richard Buchner - One of the best experts on this subject based on the ideXlab platform.
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equilibria and dynamics of sodium citrate aqueous solutIons the hydratIon of citrate and formatIon of the na3cit0 Ion aggregate
Journal of Physical Chemistry B, 2020Co-Authors: Bence Kutus, Csilla Dudas, Sergej Friesen, Gabor Peintler, Istvan Palinko, Pal Sipos, Richard BuchnerAbstract:Sodium citrate (Na3Cit) has a crucial role in many biological and industrial processes. Yet, quantitative informatIon on its hydratIon and the Ion associatIon between Na+ and Cit3– Ions in a broad ...
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hydratIon and Ion associatIon of aqueous choline chloride and chlorocholine chloride
Physical Chemistry Chemical Physics, 2019Co-Authors: Saadia Shaukat, Marija Besterrogac, Marina V Fedotova, Sergey E Kruchinin, Crtomir Podlipnik, Richard BuchnerAbstract:The choline Ion (Ch+) is ubiquitous in nature and also its synthetic homologue, chlorocholine (ClCh+), is widely used. Nevertheless, surprisingly little informatIon on the hydratIon and counter-Ion binding of these catIons can be found in the literature. In this contributIon we report effective hydratIon numbers, determined by dielectric relaxatIon spectroscopy, and Ion-pair associatIon constants with Cl-, determined by dilute-solutIon conductivity measurements. In combinatIon with RISM calculatIons the obtained data suggest that for Ch+ water is bound to the hydroxy group via hydrogen bonds whereas for ClCh+ a rather stiff clathrate-like shell around the chlorine atom seems to be formed. With Cl- both catIons form contact Ion pairs with associatIon constants of only ∼2 to 3 M-1.
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Ion associatIon of imidazolium Ionic liquids in acetonitrile
Journal of Physical Chemistry B, 2014Co-Authors: Marija Besterrogac, Alexander Stoppa, Richard BuchnerAbstract:Molar conductivities, Λ, of dilute solutIons of the Ionic liquids (ILs) 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF4]), 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]), 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), 1-hexyl-3-methylimidazolium tetrafluoroborate ([hmim][BF4]), and 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([hmim][NTf2]) in acetonitrile (AN) were determined as a functIon of temperature in the range 273.15–313.15 K. The data were analyzed with Barthel’s lcCM model to obtain limiting molar conductivities, Λ∞(T), and associatIon constants, KA°(T) of these electrolytes. The temperature dependence of these parameters, as well as the extracted limiting catIon conductivities, λi∞, were discussed. AdditIonally, dielectric spectra for [hmim][NTf2] + AN were analyzed in terms of Ion associatIon and Ion solvatIon and compared with the inference from conductivity. It appears that in dilute solutIons the imidazolium ring of the catIons is sol...
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Ion associatIon of imidazolium Ionic liquids in acetonitrile
The Journal of Physical Chemistry, 2014Co-Authors: Marija Besterrogac, Alexander Stoppa, Richard BuchnerAbstract:Molar conductivities, Λ, of dilute solutIons of the Ionic liquids (ILs) 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF₄]), 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF₄]), 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF₆]), 1-hexyl-3-methylimidazolium tetrafluoroborate ([hmim][BF₄]), and 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([hmim][NTf₂]) in acetonitrile (AN) were determined as a functIon of temperature in the range 273.15–313.15 K. The data were analyzed with Barthel’s lcCM model to obtain limiting molar conductivities, Λ∞(T), and associatIon constants, KA°(T) of these electrolytes. The temperature dependence of these parameters, as well as the extracted limiting catIon conductivities, λᵢ∞, were discussed. AdditIonally, dielectric spectra for [hmim][NTf₂] + AN were analyzed in terms of Ion associatIon and Ion solvatIon and compared with the inference from conductivity. It appears that in dilute solutIons the imidazolium ring of the catIons is solvated by ∼6 AN molecules that are slowed by a factor of ∼8–10 compared to the bulk-solvent dynamics. Ion associatIon of imidazolium ILs to contact Ion pairs is only moderate, similar to common 1:1 electrolytes in this solvent.
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A Conductance Study of Guanidinium Chloride, Thiocyanate, Sulfate, and Carbonate in Dilute Aqueous SolutIons: Ion-AssociatIon and Carbonate Hydrolysis Effects
Journal of Physical Chemistry B, 2013Co-Authors: Johannes Hunger, Roland Neueder, Richard Buchner, Alexander ApelblatAbstract:We study the conductance of dilute aqueous solutIons for a series of guandinium salts at 298.15 K. The experimental molar conductivities were analyzed within the framework of the Quint–Viallard theory in combinatIon with Debye–Huckel activity coefficients. From this analysis, we find no evidence for significant Ion associatIon in aqueous solutIons of guanidinium chloride (GdmCl) and guanidinium thiocyanate (GdmSCN), and the molar conductivity of these electrolytes can be modeled assuming a complete dissociatIon. The limiting Ionic conductivity of the guanidinium Ion (Gdm+) is accurately determined to λGdm+ = 51.45 ± 0.10 S cm2 mol–1. For the bivalent salts guanidinium sulfate (Gdm2SO4) and guanidinium carbonate (Gdm2CO3), the molar conductivities show small deviatIons from ideal (fully dissociated electrolyte) behavior, which are related to weak Ion associatIon in solutIon. Furthermore, for solutIons of Gdm2CO3, the hydrolysis of the carbonate anIon leads to distinctively increased molar conductivities at...
Hongqun Luo - One of the best experts on this subject based on the ideXlab platform.
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a sensitive assay of erythrosine using enhanced resonance scattering signals with fe phen 32 in aqueous ethanol media
Sensors and Actuators B-chemical, 2011Co-Authors: Jin Fang Liu, Ting Wen, Hongqun LuoAbstract:Abstract In a weak acidic Britton–Robinson buffer medium, erythrosine (Ery) can react with Fe(phen) 3 2+ to form 2:1 Ion-associatIon complex in the presence of ethanol, which will cause the remarkable enhancement of resonance Rayleigh scattering (RRS), second-order scattering (SOS), and frequency doubling scattering (FDS) spectra, and the appearance of new spectra of RRS, SOS, and FDS. The maximum wavelengths ( λ ex / λ em ) of the Ion-associatIon complex are located at 350 nm/350 nm for RRS, 280 nm/560 nm for SOS, and 780 nm/390 nm for FDS, respectively. The increments of scattering intensities (Δ I ) are directly proportIonal to the concentratIon of Ery in a certain range. The detectIon limits for Ery are 5.6 ng mL −1 for RRS method, 13 ng mL −1 for SOS method, and 17 ng mL −1 for FDS method, respectively. Based on the above researches, a new highly sensitive and simple method for the determinatIon of Ery has been developed. In this work, the spectral characteristics of RRS, SOS, and FDS spectra, the optimum conditIons of the reactIon and influencing factors were investigated. In additIon, the reactIon mechanism was discussed.
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resonance rayleigh scattering second order scattering and frequency doubling scattering spectra for studying the interactIon of erythrosine with fe phen 32 and its analytical applicatIon
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2011Co-Authors: Jin Fang Liu, Hongqun LuoAbstract:Abstract In a weak alkaline Britton–Robinson buffer medium, erythrosine (Ery) can react with Fe ( phen ) 3 2 + to form 1:1 Ion–associatIon complex, which will cause not only the changes of the absorptIon spectra, but also the remarkable enhancement of resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering (FDS) spectra, and the appearance of new spectra of RRS, SOS and FDS. The maximum RRS, SOS and FDS wavelengths (λex/λem) of the Ion–associatIon complex are located at 358/358 nm, 290/580 nm and 780/390 nm, respectively. The increments of scattering intensities (ΔI) are directly proportIonal to the concentratIon of Ery in a certain range. The detectIon limits for Ery are 0.028 μg mL−1 for RRS method, 0.068 μg mL−1 for SOS method and 0.11 μg mL−1 for FDS method, respectively. Among them, the RRS method has the highest sensitivity. Based on the above researches, a new highly sensitive and simple method for the determinatIon of Ery has been developed. In this work, the spectral characteristics of absorptIon, RRS, SOS and FDS spectra, the optimum conditIons of the reactIon and influencing factors for the RRS, SOS and FDS intensities were investigated. In additIon, the reactIon mechanism was discussed.
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spectrophotometric determinatIon of vitamin b1 in a pharmaceutical formulatIon using triphenylmethane acid dyes
Journal of Pharmaceutical and Biomedical Analysis, 2002Co-Authors: Shaopu Liu, Zhuyuan Zhang, Qin Liu, Hongqun Luo, Wenxu ZhengAbstract:A highly sensitive colour reactIon has been developed, based on the fact that vitamin B(1) reacted with a triphenylmethane acid dye such as thymol blue, bromothymol blue, bromophenol blue, bromocresol green, phenol red or cresol red to form an Ion-associatIon complex in a weak-base aqueous solutIon in the presence of some solubilizatIon agents e.g. polyvinyl alcohol, emulgent OP, Triton X-100 or Tween-20. The wavelengths of maximum absorbance of the six Ion-associatIon complexes were between 420 and 450 nm, and fading reactIon appeared at the longer wavelength and the maximum fading wavelengths were between 550 and 620 nm. The reactIons had highly sensitivities and their apparent molar absorptivities of the colour reactIons were (0.82-1.65) x 10(5) l mol(-1) cm(-1) and those of fading reactIons were (1.26-3.92) x 10(5) l mol(-1) cm(-1) depending on the different dye systems. The compositIon ratio of the Ion-associatIon complex was vitamin B(1):dye = 1:1 as established by Job's and equilibrium shift methods. The method had good selectivity and could be applied to direct spectrophotometric determinatIon of vitamin B(1) in aqueous phase without using organic solvent extractIon. Therefore, the method was simple and rapid. The colour reactIon mechanism was discussed with the quantum chemistry method.
Marija Besterrogac - One of the best experts on this subject based on the ideXlab platform.
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hydratIon and Ion associatIon of aqueous choline chloride and chlorocholine chloride
Physical Chemistry Chemical Physics, 2019Co-Authors: Saadia Shaukat, Marija Besterrogac, Marina V Fedotova, Sergey E Kruchinin, Crtomir Podlipnik, Richard BuchnerAbstract:The choline Ion (Ch+) is ubiquitous in nature and also its synthetic homologue, chlorocholine (ClCh+), is widely used. Nevertheless, surprisingly little informatIon on the hydratIon and counter-Ion binding of these catIons can be found in the literature. In this contributIon we report effective hydratIon numbers, determined by dielectric relaxatIon spectroscopy, and Ion-pair associatIon constants with Cl-, determined by dilute-solutIon conductivity measurements. In combinatIon with RISM calculatIons the obtained data suggest that for Ch+ water is bound to the hydroxy group via hydrogen bonds whereas for ClCh+ a rather stiff clathrate-like shell around the chlorine atom seems to be formed. With Cl- both catIons form contact Ion pairs with associatIon constants of only ∼2 to 3 M-1.
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Ion associatIon of imidazolium Ionic liquids in acetonitrile
Journal of Physical Chemistry B, 2014Co-Authors: Marija Besterrogac, Alexander Stoppa, Richard BuchnerAbstract:Molar conductivities, Λ, of dilute solutIons of the Ionic liquids (ILs) 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF4]), 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]), 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), 1-hexyl-3-methylimidazolium tetrafluoroborate ([hmim][BF4]), and 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([hmim][NTf2]) in acetonitrile (AN) were determined as a functIon of temperature in the range 273.15–313.15 K. The data were analyzed with Barthel’s lcCM model to obtain limiting molar conductivities, Λ∞(T), and associatIon constants, KA°(T) of these electrolytes. The temperature dependence of these parameters, as well as the extracted limiting catIon conductivities, λi∞, were discussed. AdditIonally, dielectric spectra for [hmim][NTf2] + AN were analyzed in terms of Ion associatIon and Ion solvatIon and compared with the inference from conductivity. It appears that in dilute solutIons the imidazolium ring of the catIons is sol...
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Ion associatIon of imidazolium Ionic liquids in acetonitrile
The Journal of Physical Chemistry, 2014Co-Authors: Marija Besterrogac, Alexander Stoppa, Richard BuchnerAbstract:Molar conductivities, Λ, of dilute solutIons of the Ionic liquids (ILs) 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF₄]), 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF₄]), 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF₆]), 1-hexyl-3-methylimidazolium tetrafluoroborate ([hmim][BF₄]), and 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([hmim][NTf₂]) in acetonitrile (AN) were determined as a functIon of temperature in the range 273.15–313.15 K. The data were analyzed with Barthel’s lcCM model to obtain limiting molar conductivities, Λ∞(T), and associatIon constants, KA°(T) of these electrolytes. The temperature dependence of these parameters, as well as the extracted limiting catIon conductivities, λᵢ∞, were discussed. AdditIonally, dielectric spectra for [hmim][NTf₂] + AN were analyzed in terms of Ion associatIon and Ion solvatIon and compared with the inference from conductivity. It appears that in dilute solutIons the imidazolium ring of the catIons is solvated by ∼6 AN molecules that are slowed by a factor of ∼8–10 compared to the bulk-solvent dynamics. Ion associatIon of imidazolium ILs to contact Ion pairs is only moderate, similar to common 1:1 electrolytes in this solvent.
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associatIon of Ionic liquids in solutIon a combined dielectric and conductivity study of bmim cl in water and in acetonitrile
Physical Chemistry Chemical Physics, 2011Co-Authors: Marija Besterrogac, Johannes Hunger, Alexander Stoppa, G T Hefter, Richard BuchnerAbstract:Ion associatIon of the Ionic liquid [bmim][Cl] in acetonitrile and in water was studied by dielectric spectroscopy for salt concentratIons c ≤ 1.3 M at 298.15 K and by measurement of molar electrical conductivities, Λ, of dilute solutIons (c ≤ 0.006 M) in the temperature range 273.15 ≲ T/K ≤ 313.15. Whilst acetonitrile solutIons of [bmim][Cl] exhibit moderate Ion pairing, with an associatIon constant of KoA ≈ 60 M−1 and increasing with temperature, [bmim][Cl] is only weakly associated in water (KoA ≈ 6 M−1) and Ion pairing decreases with rising temperature. Only contact Ion pairs were detected in both solvents. Standard-state enthalpy, entropy and heat capacity changes of Ion associatIon were derived, as well as the activatIon enthalpy of charge transport and the limiting conductivity of the catIon, λ∞([bmim]+). These data, in conjunctIon with effective solvatIon numbers obtained from the dielectric spectra, suggest that the solvatIon of [bmim]+ is much weaker in water than in acetonitrile.
G T Hefter - One of the best experts on this subject based on the ideXlab platform.
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associatIon of Ionic liquids in solutIon a combined dielectric and conductivity study of bmim cl in water and in acetonitrile
Physical Chemistry Chemical Physics, 2011Co-Authors: Marija Besterrogac, Johannes Hunger, Alexander Stoppa, G T Hefter, Richard BuchnerAbstract:Ion associatIon of the Ionic liquid [bmim][Cl] in acetonitrile and in water was studied by dielectric spectroscopy for salt concentratIons c ≤ 1.3 M at 298.15 K and by measurement of molar electrical conductivities, Λ, of dilute solutIons (c ≤ 0.006 M) in the temperature range 273.15 ≲ T/K ≤ 313.15. Whilst acetonitrile solutIons of [bmim][Cl] exhibit moderate Ion pairing, with an associatIon constant of KoA ≈ 60 M−1 and increasing with temperature, [bmim][Cl] is only weakly associated in water (KoA ≈ 6 M−1) and Ion pairing decreases with rising temperature. Only contact Ion pairs were detected in both solvents. Standard-state enthalpy, entropy and heat capacity changes of Ion associatIon were derived, as well as the activatIon enthalpy of charge transport and the limiting conductivity of the catIon, λ∞([bmim]+). These data, in conjunctIon with effective solvatIon numbers obtained from the dielectric spectra, suggest that the solvatIon of [bmim]+ is much weaker in water than in acetonitrile.
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Ion associatIon and hydratIon in 3 2 electrolyte solutIons by dielectric spectroscopy aluminum sulfate
Geochimica et Cosmochimica Acta, 2007Co-Authors: Simon Schrodle, G T Hefter, Wolfram W Rudolph, Richard BuchnerAbstract:Abstract Broadband dielectric measurements utilizing state-of-the-art coaxial reflectometry and traveling-wave interferometry have been made on aqueous solutIons of the 3:2 electrolyte aluminum sulfate at 25 °C over the frequency range 0.2 ⩽ ν (GHz) ⩽ 89 and at total solute concentratIons 0.012 ⩽ c (M) ⩽ 0.65. Detailed analysis of the solute contributIon to the dielectric spectra revealed the simultaneous presence of double solvent-separated (2SIP), solvent-shared (SIP) and contact (CIP) Ion pairs. ConcentratIons of the various Ion-pair types and the equilibrium constants for their formatIon were determined using calculated dipole moments and other relevant quantities. The 2SIPs and SIPs were found to persist down to low concentratIons in this notIonally strong electrolyte. Good agreement was found with earlier Raman and NMR studies for CIP concentratIons and with thermodynamic determinatIons of the overall Ion associatIon constant. In contrast to divalent metal sulfate solutIons, both SIPs and, to a lesser extent, 2SIPs remain present at quite high Al2(SO4)3(aq) concentratIons. The persistence of SIPs and 2SIPs was consistent with the effective hydratIon numbers obtained from an analysis of the cooperative H-bond relaxatIon mode of bulk water in the solutIons. This analysis indicated that the hydratIon of Al3+ Ions is extremely strong, with significant effects on the dielectric relaxatIon timescale even beyond the second hydratIon shell, at least in dilute solutIons.
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Ion associatIon and hydratIon in aqueous solutIons of licl and li2so4 by dielectric spectroscopy
Journal of Physical Chemistry B, 2007Co-Authors: Wolfgang Wachter, Richard Buchner, Sarka Fernandez, G T HefterAbstract:A systematic study of the dielectric relaxatIon spectra of aqueous solutIons of LiCl and Li2SO4 has been made at solute concentratIons of 0.05 < or = c/M < or = 1.0 and 2.0, respectively, and over a wide range of frequencies (0.2 < or = nu/GHz < or = 89) at 25 degrees C. The spectra were best described by a superpositIon of four Debye processes, consisting of the two well-known water relaxatIons at ca. 8 and 0.5 ps and two Ion-pair contributIons at ca. 200 and 20 ps, corresponding to the presence of double-solvent-separated (2SIP) and solvent-shared (SIP) Ion pairs, respectively. Consistent with spectroscopic studies, no contact Ion pairs were detected over the studied concentratIon range. The overall Ion associatIon constants K(o)(A) obtained were in good agreement with literature data for both salts. Detailed analysis of the solvent relaxatIons indicated that Li+ has a significant second solvatIon sheath although there were differences between the effective hydratIon numbers obtained from LiCl and Li2SO4, which might arise from competitIon for the solvent from the anIons.
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temperature effects on Ion associatIon and hydratIon in mgso4 by dielectric spectroscopy
ChemPhysChem, 2006Co-Authors: Chandrika Akilan, Nashiour Rohman, G T Hefter, Richard BuchnerAbstract:A detailed investigatIon of aqueous solutIons of magnesium sulfate has been made by dielectric relaxatIon spectroscopy (DRS) over a wide range of frequencies (0.2 ≤ ν/GHz ≤ 89), concentratIons (0.02 ≤ m/mol kg -1 ≤ 2.3) and temperatures (5 ≤ θ/°C ≤ 65). Consistent with literature data from other techniques, the spectra show clear evidence at all temperatures for the simultaneous existence of double solvent-separated (2SIP), solvent-shared (SIP) and contact (CIP) Ion pairs and a triple Ion (TI), Mg2SO42+(aq). Increased formatIon of CIPs and especially TIs occurs with increasing temperature. The overall standard Ion-associatIon constant, KA°, corresponding to the equilibrium: Mg2+(aq)+ SO42-(aq) ⇌MgSO40(aq) is in good agreement with literature data at lower temperatures but is overestimated at higher temperatures due to processing difficulties. Despite the limited precisIon of the spectra, analysis of the individual steps in the Ion-associatIon process is possible for the first time. The 2SIPs are formed with little disturbance to their hydratIon shells, the (partial) destructIon of which appears to occur mostly during the formatIon of SIPs. Effective hydratIon numbers derived from the DRS spectra indicate that both Mg2+ and SO42- influence solvent water molecules beyond their first hydratIon spheres but that MgSO4(aq) is less strongly hydrated than the previously studied CuSO4(aq).
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Ion associatIon and hydratIon in aqueous solutIons of copper ii sulfate from 5 to 65 c by dielectric spectroscopy
Journal of Physical Chemistry B, 2006Co-Authors: Chandrika Akilan, Nashiour Rohman, G T Hefter, Richard BuchnerAbstract:Aqueous solutIons of copper(II) sulfate have been studied by dielectric relaxatIon spectroscopy (DRS) over a wide range of frequencies (0.2 ≲ ν/GHz ≤ 89), concentratIons (0.02 ≤ m/mol kg-1 ≲ 1.4), and temperatures (5 ≤ t/°C ≤ 65). The spectra show clear evidence for the simultaneous existence of double-solvent-separated, solvent-shared, and contact Ion pairs at all temperatures, with increasing formatIon especially of contact Ion pairs with increasing temperature. The overall Ion associatIon constant corresponding to the equilibrium: Cu2+(aq) + SO42-(aq) ⇌ CuSO40(aq) was found to be in excellent agreement with literature data over the investigated temperature range. However, the precisIon of the spectra and other difficulties did not allow a thermodynamic analysis of the formatIon of the individual Ion-pair types. Effective hydratIon numbers derived from the DRS spectra were high but consistent with simulatIon and diffractIon data from the literature. They indicate that both Ions influence solvent water ...
Shaopu Liu - One of the best experts on this subject based on the ideXlab platform.
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resonance rayleigh scattering spectra of Ion associatIon nanoparticles of co 4 5 chloro 2 pyridyl azo 1 3 diaminobenzene 2 2 sodium dodecyl benzene sulfonate system and its analytical applicatIon
Analytica Chimica Acta, 2009Co-Authors: Qingling Yang, Zhongfang Liu, Shaopu Liu, Gangcai Chen, Hui Duan, Dan Song, Jian Wang, Jian LiuAbstract:In pH 1.8-3.0 Britton-Robinson (BR) buffer solutIon, cobalt (II) reacts with 4-[(5-Chloro-2-pyridyl) azo]-1, 3-diaminobenzene (5-Cl-PADAB, L) to form a catIonic chelate [CoL(2)](2+). When interacting with anIonic surfactants (AS) such as sodium dodecyl benzene sulfonate (SDBS), sodium dodecyl sulfate (SDS) or sodium dodecyl sulfonate (SLS), the chelate can only react with SDBS to form ternary Ion-associatIon complexes ([CoL(2)][SDBS](2)). By virtue of the extrusIon actIon of water and Van der Waals force, the hydrophobic Ion-associatIon complexes draw close to each other and further aggregate to form {[CoL(2)][SDBS](2)}(n) nanoparticles with an average diameter of 30 nm. As a result, resonance Rayleigh scattering (RRS) is enhanced greatly and new RRS spectra appear. Under the same conditIons, both SDS and SLS exhibit no similar reactIons and do not result in obvious change of RRS. Therefore, SDBS can be determined selectively by RRS method in the presence of SDS or SLS. The wavelength of 516 nm was chosen as a detectIon wavelength, the linear range and the detectIon limit (3sigma) are 0.05-6.0 microg mL(-1) and 0.015 microg mL(-1) for the determinatIon of SDBS, respectively. The characteristics of RRS spectra of the [CoL(2)](2+)-SDBS system, the optimum conditIons of the reactIon and the influencing factors have been investigated. The effects of coexisting substances have been examined too, indicating a good selectivity of the method for the determinatIon of SDBS. The method can be used for the determinatIon of SDBS in waste water and river water samples, and the results are satisfactory compared with those of standard samples of SDBS. Based on the formatIon of {[CoL(2)][SDBS](2)}(n) nanoparticles, a sensitive, simple and rapid method has been developed for the determinatIon of SDBS in environmental water samples using a RRS technique. Moreover, the reactIon mechanism was discussed.
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resonance rayleigh scattering method for the determinatIon of sildenafil citrate in a pharmaceutical formulatIon using evans blue
Analytical Sciences, 2006Co-Authors: Shaopu Liu, Li Fan, Zhongfang LiuAbstract:A highly sensitive resonance Rayleigh-scattering (RRS) method for the determinatIon of sildenafil citrate has been developed, based on the fact that sildenafil (Sild) reacted with Evans Blue (EB) to form an Ion-associatIon complex in pH 1.1 - 4.6 aqueous solutIon. This resulted in a significant enhancement of the RRS intensity, and a new spectrum appeared. The wavelength of the maximum RRS was at 365 nm, and other scattering peaks were at 400, 442, 470 and 534 nm, respectively. The intensity of RRS was directly proportIonal to the concentratIon of Sild in the range 0 - 11.5 µg ml-1, and the detectIon limit for Sild (3 σ) was 30.3 ng ml-1. The compositIon of the Ion-associatIon complex was Sild:EB = 1:1, as established by Job's method. The method had good selectivity and could be applied to the determinatIon of Sild in the aqueous phase without using organic solvent extractIon. The method was simple and rapid. In additIon, the reactIon mechanism and the reason for RRS enhancement were considered.
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spectrophotometric determinatIon of vitamin b1 in a pharmaceutical formulatIon using triphenylmethane acid dyes
Journal of Pharmaceutical and Biomedical Analysis, 2002Co-Authors: Shaopu Liu, Zhuyuan Zhang, Qin Liu, Hongqun Luo, Wenxu ZhengAbstract:A highly sensitive colour reactIon has been developed, based on the fact that vitamin B(1) reacted with a triphenylmethane acid dye such as thymol blue, bromothymol blue, bromophenol blue, bromocresol green, phenol red or cresol red to form an Ion-associatIon complex in a weak-base aqueous solutIon in the presence of some solubilizatIon agents e.g. polyvinyl alcohol, emulgent OP, Triton X-100 or Tween-20. The wavelengths of maximum absorbance of the six Ion-associatIon complexes were between 420 and 450 nm, and fading reactIon appeared at the longer wavelength and the maximum fading wavelengths were between 550 and 620 nm. The reactIons had highly sensitivities and their apparent molar absorptivities of the colour reactIons were (0.82-1.65) x 10(5) l mol(-1) cm(-1) and those of fading reactIons were (1.26-3.92) x 10(5) l mol(-1) cm(-1) depending on the different dye systems. The compositIon ratio of the Ion-associatIon complex was vitamin B(1):dye = 1:1 as established by Job's and equilibrium shift methods. The method had good selectivity and could be applied to direct spectrophotometric determinatIon of vitamin B(1) in aqueous phase without using organic solvent extractIon. Therefore, the method was simple and rapid. The colour reactIon mechanism was discussed with the quantum chemistry method.
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resonance rayleigh scattering of chromium vi iodide basic triphenylmethane dye systems and their analytical applicatIon
Analytica Chimica Acta, 1999Co-Authors: Shaopu Liu, Zhongfang Liu, Qin Liu, Cheng Zhi HuangAbstract:Abstract Resonance Rayleigh scattering (RRS) of chromium(VI)-iodide-basic triphenylmethane dye (BPTMD) systems and their analytical applicatIons have been studied. In dilute phosphoric acid solutIon in the presence of excess I − , chromium(VI) oxidizes I − producing I 2 , which binds I − to form I − 3 and I − 3 further reacts with a basic triphenylmethane dye such as crystal violet (CV), ethyl violet (EV), malachite green (MG), brilliant green (BG) and iodine green (IG) to form an Ion-associatIon complex. This results in the significant enhancement of RRS intensity and the appearance of new RRS spectra. The characteristics of RRS spectra of the Ion-associatIon complexes, the affecting factors and the optimum conditIons of these reactIons have been investigated. The intensity of RRS is directly proportIonal to the concentratIon of chromium(VI) in the range 0–1.5 μg/25 ml for the CV system and 0–1.0 μg/25 ml for the other systems. The methods have very high sensitivity and the detectIon limits for Cr(VI) are 0.065–5.6 ng ml −1 depending on the different reactIon systems; the CV system is the most sensitive. A new method for the indirect determinatIon of trace chromium(VI) on the basis of RRS has been advanced.
