Flurbiprofen(FB),a nonsteroidal anti-inflammatory drug,is widely employed in treating ocular inflammation owing to its remarkable anti-inflammatory effects.However,the racemic nature of its commercially available form...Flurbiprofen(FB),a nonsteroidal anti-inflammatory drug,is widely employed in treating ocular inflammation owing to its remarkable anti-inflammatory effects.However,the racemic nature of its commercially available formulation(Ocufen^(R))limits the full potential of its therapeutic activity,as the(S)-enantiomer is responsible for the desired antiinflammatory effects.Additionally,the limited corneal permeability of FB significantly restricts its bioavailability.In this study,we successfully separated the chiral isomers of FB to obtain the highly active(S)-FB.Subsequently,utilizing ion-pairing technology,we coupled(S)-FB with various counter-ions,such as sodium,diethylamine,trimethamine(TMA),and l-arginine,to enhance its ocular bioavailability.A comprehensive evaluation encompassed balanced solubility,octanol-water partition coefficient,corneal permeability,ocular pharmacokinetics,tissue distribution,and in vivo ocular anti-inflammatory activity of each chiral isomer salt.Among the various formulations,S-FBTMA exhibited superior water solubility(about 1–12 mg/ml),lipid solubility(1<lgP_(ow)<3)and corneal permeability.In comparison to Ocufen^(R),S-FBTMA demonstrated significantly higher in vivo antiinflammatory activity and lower ocular irritability(such as conjunctival congestion and tingling).The findings from this research highlight the potential of chiral separation and ion-pair enhanced permeation techniques in providing pharmaceutical enterprises focused on drug development with a valuable avenue for improving therapeutic outcomes.展开更多
fragments, F- and Cl- including two isotope species 35Cl- and 37Cl-, are observed in the photoexcitations of CFC13. The ion-pair anion efficiency spectra of 35Cl- and 37Cl- are recorded in the photon energy range of 7...fragments, F- and Cl- including two isotope species 35Cl- and 37Cl-, are observed in the photoexcitations of CFC13. The ion-pair anion efficiency spectra of 35Cl- and 37Cl- are recorded in the photon energy range of 7.75-22.00 eV. The threshold of ion-pair dissociation CFCl3-CFC12＋＋Cl- is experimentally determined to be 7.944-0.04 eV. With the references of the high-resolution photoabsorption spectra reported in the literatures, we make tentative assignments of the electron valence-to-Rydberg transitions. Furthermore, the multibody ion-pair fragmentation processes to Cl- are discussed by comparison between the calculated thermochemical thresholds and the experimental efficiency spectrum.展开更多
An efficient and sensitive ion-pair HPLC-UV method using atenolol as internal standard （IS） was developed and validated for the determination of metformin in the plasma of diabetic rats. Plasma samples were deprotei...An efficient and sensitive ion-pair HPLC-UV method using atenolol as internal standard （IS） was developed and validated for the determination of metformin in the plasma of diabetic rats. Plasma samples were deproteinated with 10% （v/v） perchloric acid. Separation was achieved on a UltimateTM AQ-C18 column （250 mm×4.6 mm, 5 μm） with a mobile phase （pH 5.05） composed of acetonitrile-water （31：69, v/v, containing 0.002 M sodium dodecyl sulfate, 0.0125 M potassium dihydrogen phosphate, 0.015 M triethylamine） at a flow rate of 1.0 mL/min. The calibration curve was linear （r〉0.994） between 7.5 and 4000 ng/mL. The lower limit of quantification （LLOQ） was 7.5 ng/mL. The precision was validated and the relative standard deviation was in the range of 1.87% to 15.70%; the accuracy was between 93.98%-106.89%. The mean recoveries were 95.40% and 95.31% for metformin and IS, respectively. The relative error （RE） of stability at different storage conditions was within ±9.00%. This method was used to determine the concentration-time profile of metformin in diabetic rat plasma following an oral administration of metformin at the dose of 10 mg/kg. Our results indicated that ion-pair HPLC-UV method using UltimateTM AQ-C18 column was effective for the pharmacokinetic studies of high polarity compounds like metformin.展开更多
A method for rapid and simultaneous determination of imidazolium and pyridinium ionic liquid cations by ion-pair chromatography with ultraviolet detection was developed. Chromatographic separations were performed on a...A method for rapid and simultaneous determination of imidazolium and pyridinium ionic liquid cations by ion-pair chromatography with ultraviolet detection was developed. Chromatographic separations were performed on a reversed-phase silica-based monolithic column using 1-heptanesulfonic acid sodium-acetonitrile as mobile phase. The effects of ion-pair reagent and acetonitrile concentration on retention of the cations were investigated. The retention times of the cations accord with carbon number rule. The method has been successfully applied to the determination of four ionic liquids synthesized by organic chemistry laboratory.展开更多
Ion-pairing high-performance liquid chromatography-ultraviolet （HPLC-UV） methods were developed to determine two commonly used chelating agents, ethylenediaminetetraacetic acid （EDTA） in Abilify （a small molecule...Ion-pairing high-performance liquid chromatography-ultraviolet （HPLC-UV） methods were developed to determine two commonly used chelating agents, ethylenediaminetetraacetic acid （EDTA） in Abilify （a small molecule drug with aripiprazole as the active pharmaceutical ingredient） oral solution and die- thylenetriaminepentaacetic acid （DTPA） in Yervoy （a monoclonal antibody drug with ipilimumab as the active pharmaceutical ingredient） intravenous formulation. Since the analytes, EDTA and DTPA, do not contain chromophores, transition metal ions （Cu2＋, Fe3＋） which generate highly stable metallocom- plexes with the chelating agents were added into the sample preparation to enhance UV detection. The use of metallocomplexes with ion-pairing chromatography provides the ability to achieve the desired sensitivity and selectivity in the development of the method. Specifically, the sample preparation in- volving metallocomplex formation allowed sensitive UV detection. Copper was utilized for the de- termination of EDTA and iron was utilized for the determination of DTPA. In the case of EDTA, a gradient mobile phase separated the components of the formulation from the analyte. In the method for DTPA, the active drug substance, ipilimumab, was eluted in the void. In addition, the optimization of the concentration of the ion-pairing reagent was discussed as a means of enhancing the retention of the aminopolycarboxylic acids （APCAs） including EDTA and DTPA and the specificity of the method. The analytical method development was designed based on the chromatographic properties of the analytes, the nature of the sample matrix and the intended purpose of the method. Validation data were presented for the two methods. Finally, both methods were successfully utilized in determining the fate of the chelates.展开更多
A method was developed for the determination of tetraethyl ammonium （TEA） by reversed-phase ion- pair chromatography with indirect ultraviolet detection, Chromatographic separation was achieved on a reversed-phase C...A method was developed for the determination of tetraethyl ammonium （TEA） by reversed-phase ion- pair chromatography with indirect ultraviolet detection, Chromatographic separation was achieved on a reversed-phase C18 column using background ultraviolet absorbing reagent - ion-pair reagent - organic solvent as mobile phase. The effects of the background ultraviolet absorbing reagents, detection wavelength, ion-pair reagents, organic solvents and column temperature on the determination method were investigated and the retention rules discussed. Results found that TEA could be successfully analyzed by using 0.7 mmol/L 4-aminophenol hydrochloride and 0.15 mmol/L 1-heptanesulfonic acid sodium mixed with 20% （v/v） methanol as mobile phase at a UV detection wavelength of 230 nm. Under these conditions, the retention time of tetraethyl ammonium was 2.85 min. The detection limit （S/N = 3） for TEA was 0.06 mg/L. The relative standard deviations （n = 5） for peak area and retention time were 0.35% and 0.02%, respectively. The method has been successfully applied to the determination of synthesized tetraethyl ammonium bromide. Recovery of tetraethyl ammonium after spiking was 99.1%.展开更多
Fast analysis of thiocyanate by ion-pair chromatography using a silica-based monolithic column and direct conductivity detection was carried out. Chromatographic separation was performed on a Chromolith Speed ROD RP-1...Fast analysis of thiocyanate by ion-pair chromatography using a silica-based monolithic column and direct conductivity detection was carried out. Chromatographic separation was performed on a Chromolith Speed ROD RP-18e using tetrabutylammonium hydroxide （TBA）-phthalic acid-acetonitrile as eluent. The effects of eluent concentration, eluent pH value, column temperature and flow rate on retention time of thiocyanate were investigated. The optimized chromatographic conditions for the determination of thiocyanate were as follows： 0.25 mmol/L TBA-0.18 mmol/L phthalate-7% acetonitrile （pH 5.5） as eluent, column temperature of 30 ℃, and flow rate of 6.0 mL/min. Retention time of thiocyanate was less than 1 min under the conditions. Common anions （Cl^-, NO3 , SO42 and I^- ） did not interfere with the determination of thiocyanate. Detection limit （S/N = 3） of thiocyanate was 0.96 mg/L. Calibration graph between peak area and the concentration of thiocyanate was linear in the range of 2.0- 100.0 mg/L. Relative standard deviation （RSD） of chromatographic peak area was 1.4% （n = 5）. This method has been applied to the determination of thiocyanate in ionic liquids. Recoveries of thiocyanate after spiking were 100.5%.展开更多
The intramolecular electronic communication and multilevel ion-pairing effect of triferrocenylmethane（TriFcM） in organic phase was studied with the ＂thin-layer electrochemistry＂ approach.Three pairs of symmetric p...The intramolecular electronic communication and multilevel ion-pairing effect of triferrocenylmethane（TriFcM） in organic phase was studied with the ＂thin-layer electrochemistry＂ approach.Three pairs of symmetric peaks in cyclic voltammetry of TriFcM correspond to three one-electron electrochemical reaction processes and indicate strong intramolecular electronic communication,which could be used to study the multilevel ion-pairing effect.Three different formation constants of ion-pairs between the three ferroceniums of TriFcM and perchlorate in thin organic film were obtained and compared.展开更多
Investigation of amino acids in hydrothermal systems is of prime importance for the understanding of geochemistry and microbiology of hydrothermal vents and plumes, for carbon and metals global cycles, for metabolism ...Investigation of amino acids in hydrothermal systems is of prime importance for the understanding of geochemistry and microbiology of hydrothermal vents and plumes, for carbon and metals global cycles, for metabolism of some hydrothermal microorganisms and for the origin of life issue. Extensive theoretical and experimental work on amino acids behaviour in hydrothermal fluids has been done, conversely only few data exist on natural samples. Because each hydrothermal vent is unique, the more data we collect the better we will be able to address each of these questions. Usually amino acids in hydrothermal fluids have been measured by HPLC-FLD. The chromatographic separation was at least 26 min and up to 135 min and the required derivatization step may be time consuming, may use harmful chemicals and may be source of contamination. Alternatively, we describe here a method combining quickness (4.5 min), high resolution (10,000), very low LOD (sub-ppb) and without derivatization. Characterisation and separation of 10 relevant proteinogenic underivatized amino acids was achieved by ion-pairing reversed-phase Ultra-high Performance Liquid Chromatography-Electrospray Ionisation-Quadrupole Time of Flight-Mass Spectrometry (UPLC-ESI-QTOF-MS). Excellent linearity in the response was obtained for all amino acids with correlation coefficients > 0.9921. This method was successfully applied to natural hydrothermal fluid samples from ultramafic-hosted vents of the Mid-Atlantic Ridge region. Results are consistent with the only 2 other studies published on ultramafic-hosted vents and complete the few available data.展开更多
This paper proposes the use of novel surfactant additives for the separation of organic acids by ion-pair chromatography and studies the influences of surfactants on the chromatographic separation behaviors.Researches...This paper proposes the use of novel surfactant additives for the separation of organic acids by ion-pair chromatography and studies the influences of surfactants on the chromatographic separation behaviors.Researches have been carried out on both silica gel matrix and polymer supporters in order to compare the two ordinary kinds of stationary phases,and the phenomenon is similar. Separation is based on differences in the stabilities of analyte-additive complexes in solution.Retention times of analytes can ...展开更多
Enantiomers of four amino alcohols were resolved by ion-pair chromatography with (+)-10-camphorsulphonic acid as chiral counter ion. Studies of the influence of the mobile phase composition, the solute structure and t...Enantiomers of four amino alcohols were resolved by ion-pair chromatography with (+)-10-camphorsulphonic acid as chiral counter ion. Studies of the influence of the mobile phase composition, the solute structure and the mobile phase flow-rate on separation are presented. Under the optimized conditions enantiomeric propanolol, norephedrine, metropolol and salbutamol were separated using dichloromethane-1-pentanol (97:3 v/v) as mobile phase on Lichrospher-100-DIOL column.展开更多
The selected-state probabilities of collinear ion-pair formation process Na+I2→Na++I2-on Aten-Laming-Los two-State potential energy surface have been calculated by using LCAC-SW method. The results show that reaction...The selected-state probabilities of collinear ion-pair formation process Na+I2→Na++I2-on Aten-Laming-Los two-State potential energy surface have been calculated by using LCAC-SW method. The results show that reaction probabilities are oscillatory with collision energy; the threshold energy of this ioniZation reaction is 2.8 ev, which is in modest agreement with experimental result.展开更多
A novel compound [Cl2Bz（3-MeQl） ]（TCNQ） （[Cl2Bz（3-MeQl） ]^＋ = 1-（3,4-dichlo-robenzyl） 3-methlquinoline cation,TCNQ-= 7,7,8,8-tetracyanoquinodimethanide anion） has been synthesized by the reaction of [Cl2Bz...A novel compound [Cl2Bz（3-MeQl） ]（TCNQ） （[Cl2Bz（3-MeQl） ]^＋ = 1-（3,4-dichlo-robenzyl） 3-methlquinoline cation,TCNQ-= 7,7,8,8-tetracyanoquinodimethanide anion） has been synthesized by the reaction of [Cl2Bz（3-MeQl） ]Br and LiTCNQ,and its structure was determined by single-crystal X-ray diffraction. The crystal belongs to monoclinic,space group P21/c. The structure analysis shows that the anions are stacked into a column with isolated π-dimers,and there is one type of TCNQ entries（TCNQ^-） ,in agreement with the IR spectra analysis and density functional theory calculations of the compound. The most prominent structural features are the completely segregated stacking columns of the TCNQ- anions and [Cl2Bz（3-MeQl）]＋ cations.展开更多
The ion-pair compound [H2（teta）]^2＋·[Ni（CN）4]^2-·2H2O （C20H42N8NiO2, teta = meso- 5,7,7,12,14,14-hexamethyl- 1,4,8,11-tetraazacyclotetradecane） was synthesized and characterized by single-crystal X-ra...The ion-pair compound [H2（teta）]^2＋·[Ni（CN）4]^2-·2H2O （C20H42N8NiO2, teta = meso- 5,7,7,12,14,14-hexamethyl- 1,4,8,11-tetraazacyclotetradecane） was synthesized and characterized by single-crystal X-ray diffraction. The crystal belongs to monoclinic, space group P211n with a = 10.0784（10）, b = 9.5411（7）, c = 14.1010（14）А, β= 106.752（2）°, V= 1298.4（2）A^3, Mr = 485.33, Z= 2, De= 1.241 g/cm^3,μ（MoKα） = 0.778 mm^-1 and F（000） = 524. The structure was refined to R = 0.0391 and wR = 0.0870 for 2614 observed reflections with I 〉 2σ（I）. The title compound contains one [Ni（CN）4]^2- anion, one protonated macrocyclic tetraamine cation [H2（teta）]^2＋ and two water molecules. There are multiform hydrogen bonds in the compound to link the different components and stabilize the crystal structure.展开更多
The title compound [BrBzPy][TCNQ] （BrBzPy^＋=1-（4-bromobenzyl）pyridinium cation, TCNQ = 7,7,8,8-tetracyanoquinodimethanide anion） was synthesized by the reaction of [BrBzPy]Br and LiTCNQ in ethanol solution and it...The title compound [BrBzPy][TCNQ] （BrBzPy^＋=1-（4-bromobenzyl）pyridinium cation, TCNQ = 7,7,8,8-tetracyanoquinodimethanide anion） was synthesized by the reaction of [BrBzPy]Br and LiTCNQ in ethanol solution and its structure was determined by single-crystal X-ray diffraction. The crystal belongs to monoclinic, space group P21/c with a = 14.067（3）, b = 7.3089（14）, c = 23.796（4）A, β = 122.011（9）°, V= 2074.6（7）A^3, Z = 4, C24H15BrN5, Mr = 453.32, Dc = 1.451 g/cm^3,μ = 2.002 mm^-1, S = 1.047, F（000） = 916, R = 0.0398 and wR = 0.0921. The most prominent structural features are the completely segregated stacking columns of the TCNQ- anions and [BrBzPy]^＋ cations. In a TCNQ column, the centroid-to-centroid distances of the neighboring anions of TCNQ are 3.2693 and 4.9464 A, respectively.展开更多
A novel compound [（CNBz）2Im]2（TCNQ）3（CH3CN）（（CNBz）2Im = 1,3-bis（4-cyano-benzyl） imidazole cation,TCNQ-1 = 7,7,8,8-tetracyanoquinodimethanide anion） was synthesized by the reaction of [（CNBz）2Im]Br and Li...A novel compound [（CNBz）2Im]2（TCNQ）3（CH3CN）（（CNBz）2Im = 1,3-bis（4-cyano-benzyl） imidazole cation,TCNQ-1 = 7,7,8,8-tetracyanoquinodimethanide anion） was synthesized by the reaction of [（CNBz）2Im]Br and LiTCNQ in water and its structure was determined by single-crystal X-ray diffraction.The crystal belongs to monoclinic,space group P21/c with a = 10.1823（17）,b = 20.292（3）,c = 16.952（3） ,β = 104.73（0）°,V = 3387.6（10）3,Z = 4,C39H24N11,Mr = 646.69,Dc = 1.268 g/cm3,μ = 0.080 mm-1 and F（000） = 1340.The structure was solved by direct methods and refined to R = 0.0596 and wR = 0.0911 for 2690 observed reflections（Ⅰ 〉 2σ（Ⅰ））.The most prominent structural feature is that there are two types of TCNQ entries（TCNQ-1 and TCNQ0） in agreement with the IR spectra analysis of the compound.展开更多
A novel ion-pair palladium（Ⅱ） compound, （NOzBzPy）2[Pd（dmit）2] （NO2BzPy^＋ = 1-（4-nitrobenzyl）pyridinium, dmit^2- = 2-thioxo-1,3-dithiole-4,5-bis（thiolate））, was synthesized and characterized by single-cry...A novel ion-pair palladium（Ⅱ） compound, （NOzBzPy）2[Pd（dmit）2] （NO2BzPy^＋ = 1-（4-nitrobenzyl）pyridinium, dmit^2- = 2-thioxo-1,3-dithiole-4,5-bis（thiolate））, was synthesized and characterized by single-crystal X-ray structure determination. This compound crystallizes in the monoclinic system, space group P21/n with a = 10.4463（11）, b = 8.5627（9）, e = 20.017（2）A, β = 97.7730（10）°, V = 1774.1（3）A^3, Z = 2, C30H22N4O4S10Pd, Mr = 929.52, Dc = 1.740 g/cm^3,μ = 1.155 mm^-1, S = 1.006, F（000） = 936, R = 0.0354 and wR = 0.0675. The most intriguing general structural feature of the compound is the completely segregated columnar stacks of anions and cations. There exist hydrogen-bonding interactions within the cation column.展开更多
For the Li + I2 →Li+ + I2- system, theoretical study has been performed on the QCISD(T) level by using the ab initio method. The collision complex in ion-pair formation process was found and optimized. These results ...For the Li + I2 →Li+ + I2- system, theoretical study has been performed on the QCISD(T) level by using the ab initio method. The collision complex in ion-pair formation process was found and optimized. These results show that the crossed molecule beam (CMB) experimental phenomenon is verified and the detailed geometry is given for the first time. A mechanism for ion-pair formation was proposed in detail. The position where the collision complex occurs affects the reaction path. Specifically, the process has threshold when the collision complex appeared before the crossing point between the covalent and ionic state potential energy surfaces. On the contrary, the process has no threshold after the crossing point. Theoretically, the title system belongs to the former case.展开更多
Lithium(Li)is an important energy metal in the 21st century.However,the selective recovery of Li is still a big challenge,especially from acidic solutions with multiple metal ions existence.Herein we report a new ion ...Lithium(Li)is an important energy metal in the 21st century.However,the selective recovery of Li is still a big challenge,especially from acidic solutions with multiple metal ions existence.Herein we report a new ion pair induced mechanism for selectively extracting Li^(+)from acidic chloride solutions by tributyl phosphate(TBP).It is shown that the acidity and the chloride ions in the aqueous phase have great effects on the extraction of Li^(+).The FT-IR,UV-Vis and ESI-MS experiments provide solid evidence for the formation of ion-pair complex[Li(TBP)_n(H_(2)O)_(m)]^(+)[FeCl_(4)]^(-)(n-1,2,3;m-0,1)in the organic phase,which brings about the effective and efficient extraction of Li^(+).This mechanism can overcome the Hofmeister bias and allow for the selective extraction of Li^(+) from the extremely hydrophilic chlorides.It has also been proved that the loaded Li in TBP can be effectively stripped by concentrated HCl solution with a Li/Fe separation factor>500.The understanding of the ion-pair transport mechanism is helpful for optimizing the recovery process or further advancing more efficient recovery techniques for Li from acidic liquor.展开更多
Ion-pair dissociation is an important molecular process and frequently happens when the target molecule is pumped to its electronically superexcited states. In contrast to the experimental studies of photoexcitation i...Ion-pair dissociation is an important molecular process and frequently happens when the target molecule is pumped to its electronically superexcited states. In contrast to the experimental studies of photoexcitation ion-pair dissociation, there are some experimental challenges in the electron-impact ion-pair dissociation study, in particular, on determination of the energetic threshold. Here we report an experimental development for the ion-pair dissociation study by using the monochromized electron impacts. As an example, the threshold of BrCN→Br^-+CN^+ is determined as 13.78 eV according to the appearance energy of CN^+ signals, meanwhile, the time-sliced ion velocity image of CN^+ is recorded at 16.09 eV and indicates an anisotropic distribution of the CN^+ momentum.展开更多
基金financially supported by the National Postdoctoral Foundation of China(No.2023M730375)Liaoning Province Department of Education Project(No.LJKMZ20221365)the State Key Laboratory of Natural and Biomimetic Drugs(No.K202215)。
文摘Flurbiprofen(FB),a nonsteroidal anti-inflammatory drug,is widely employed in treating ocular inflammation owing to its remarkable anti-inflammatory effects.However,the racemic nature of its commercially available formulation(Ocufen^(R))limits the full potential of its therapeutic activity,as the(S)-enantiomer is responsible for the desired antiinflammatory effects.Additionally,the limited corneal permeability of FB significantly restricts its bioavailability.In this study,we successfully separated the chiral isomers of FB to obtain the highly active(S)-FB.Subsequently,utilizing ion-pairing technology,we coupled(S)-FB with various counter-ions,such as sodium,diethylamine,trimethamine(TMA),and l-arginine,to enhance its ocular bioavailability.A comprehensive evaluation encompassed balanced solubility,octanol-water partition coefficient,corneal permeability,ocular pharmacokinetics,tissue distribution,and in vivo ocular anti-inflammatory activity of each chiral isomer salt.Among the various formulations,S-FBTMA exhibited superior water solubility(about 1–12 mg/ml),lipid solubility(1<lgP_(ow)<3)and corneal permeability.In comparison to Ocufen^(R),S-FBTMA demonstrated significantly higher in vivo antiinflammatory activity and lower ocular irritability(such as conjunctival congestion and tingling).The findings from this research highlight the potential of chiral separation and ion-pair enhanced permeation techniques in providing pharmaceutical enterprises focused on drug development with a valuable avenue for improving therapeutic outcomes.
文摘fragments, F- and Cl- including two isotope species 35Cl- and 37Cl-, are observed in the photoexcitations of CFC13. The ion-pair anion efficiency spectra of 35Cl- and 37Cl- are recorded in the photon energy range of 7.75-22.00 eV. The threshold of ion-pair dissociation CFCl3-CFC12＋＋Cl- is experimentally determined to be 7.944-0.04 eV. With the references of the high-resolution photoabsorption spectra reported in the literatures, we make tentative assignments of the electron valence-to-Rydberg transitions. Furthermore, the multibody ion-pair fragmentation processes to Cl- are discussed by comparison between the calculated thermochemical thresholds and the experimental efficiency spectrum.
基金National Integrity Innovational Technology Platform of New Drug and Research and Development (Grant No.2009ZX09201-010)Innovation Team of Ministry of Education(Grant No. BMU20110263)
文摘An efficient and sensitive ion-pair HPLC-UV method using atenolol as internal standard （IS） was developed and validated for the determination of metformin in the plasma of diabetic rats. Plasma samples were deproteinated with 10% （v/v） perchloric acid. Separation was achieved on a UltimateTM AQ-C18 column （250 mm×4.6 mm, 5 μm） with a mobile phase （pH 5.05） composed of acetonitrile-water （31：69, v/v, containing 0.002 M sodium dodecyl sulfate, 0.0125 M potassium dihydrogen phosphate, 0.015 M triethylamine） at a flow rate of 1.0 mL/min. The calibration curve was linear （r〉0.994） between 7.5 and 4000 ng/mL. The lower limit of quantification （LLOQ） was 7.5 ng/mL. The precision was validated and the relative standard deviation was in the range of 1.87% to 15.70%; the accuracy was between 93.98%-106.89%. The mean recoveries were 95.40% and 95.31% for metformin and IS, respectively. The relative error （RE） of stability at different storage conditions was within ±9.00%. This method was used to determine the concentration-time profile of metformin in diabetic rat plasma following an oral administration of metformin at the dose of 10 mg/kg. Our results indicated that ion-pair HPLC-UV method using UltimateTM AQ-C18 column was effective for the pharmacokinetic studies of high polarity compounds like metformin.
基金supported by the Natural Science Foundation of Heilongjiang Province(No.B200909)the Program for Scientific and Technological Innovation Team Construction in Universities of Heilongjiang Province(No. 2011TD010)
文摘A method for rapid and simultaneous determination of imidazolium and pyridinium ionic liquid cations by ion-pair chromatography with ultraviolet detection was developed. Chromatographic separations were performed on a reversed-phase silica-based monolithic column using 1-heptanesulfonic acid sodium-acetonitrile as mobile phase. The effects of ion-pair reagent and acetonitrile concentration on retention of the cations were investigated. The retention times of the cations accord with carbon number rule. The method has been successfully applied to the determination of four ionic liquids synthesized by organic chemistry laboratory.
文摘Ion-pairing high-performance liquid chromatography-ultraviolet （HPLC-UV） methods were developed to determine two commonly used chelating agents, ethylenediaminetetraacetic acid （EDTA） in Abilify （a small molecule drug with aripiprazole as the active pharmaceutical ingredient） oral solution and die- thylenetriaminepentaacetic acid （DTPA） in Yervoy （a monoclonal antibody drug with ipilimumab as the active pharmaceutical ingredient） intravenous formulation. Since the analytes, EDTA and DTPA, do not contain chromophores, transition metal ions （Cu2＋, Fe3＋） which generate highly stable metallocom- plexes with the chelating agents were added into the sample preparation to enhance UV detection. The use of metallocomplexes with ion-pairing chromatography provides the ability to achieve the desired sensitivity and selectivity in the development of the method. Specifically, the sample preparation in- volving metallocomplex formation allowed sensitive UV detection. Copper was utilized for the de- termination of EDTA and iron was utilized for the determination of DTPA. In the case of EDTA, a gradient mobile phase separated the components of the formulation from the analyte. In the method for DTPA, the active drug substance, ipilimumab, was eluted in the void. In addition, the optimization of the concentration of the ion-pairing reagent was discussed as a means of enhancing the retention of the aminopolycarboxylic acids （APCAs） including EDTA and DTPA and the specificity of the method. The analytical method development was designed based on the chromatographic properties of the analytes, the nature of the sample matrix and the intended purpose of the method. Validation data were presented for the two methods. Finally, both methods were successfully utilized in determining the fate of the chelates.
基金supported by the Natural Science Foundation of Heilongjiang Province(Grant No.B201307)the Ministry of Education of Heilongjiang Province(No.12531192)the Program for Scientific and Technological Innovation Team Construction in Universities of Heilongjiang Province(No. 2011TD010)
文摘A method was developed for the determination of tetraethyl ammonium （TEA） by reversed-phase ion- pair chromatography with indirect ultraviolet detection, Chromatographic separation was achieved on a reversed-phase C18 column using background ultraviolet absorbing reagent - ion-pair reagent - organic solvent as mobile phase. The effects of the background ultraviolet absorbing reagents, detection wavelength, ion-pair reagents, organic solvents and column temperature on the determination method were investigated and the retention rules discussed. Results found that TEA could be successfully analyzed by using 0.7 mmol/L 4-aminophenol hydrochloride and 0.15 mmol/L 1-heptanesulfonic acid sodium mixed with 20% （v/v） methanol as mobile phase at a UV detection wavelength of 230 nm. Under these conditions, the retention time of tetraethyl ammonium was 2.85 min. The detection limit （S/N = 3） for TEA was 0.06 mg/L. The relative standard deviations （n = 5） for peak area and retention time were 0.35% and 0.02%, respectively. The method has been successfully applied to the determination of synthesized tetraethyl ammonium bromide. Recovery of tetraethyl ammonium after spiking was 99.1%.
基金supported by the Program for Scientifc and Technological Innovation Team Construction in Universities of Heilongjiang Province (No. 2011TD010)
文摘Fast analysis of thiocyanate by ion-pair chromatography using a silica-based monolithic column and direct conductivity detection was carried out. Chromatographic separation was performed on a Chromolith Speed ROD RP-18e using tetrabutylammonium hydroxide （TBA）-phthalic acid-acetonitrile as eluent. The effects of eluent concentration, eluent pH value, column temperature and flow rate on retention time of thiocyanate were investigated. The optimized chromatographic conditions for the determination of thiocyanate were as follows： 0.25 mmol/L TBA-0.18 mmol/L phthalate-7% acetonitrile （pH 5.5） as eluent, column temperature of 30 ℃, and flow rate of 6.0 mL/min. Retention time of thiocyanate was less than 1 min under the conditions. Common anions （Cl^-, NO3 , SO42 and I^- ） did not interfere with the determination of thiocyanate. Detection limit （S/N = 3） of thiocyanate was 0.96 mg/L. Calibration graph between peak area and the concentration of thiocyanate was linear in the range of 2.0- 100.0 mg/L. Relative standard deviation （RSD） of chromatographic peak area was 1.4% （n = 5）. This method has been applied to the determination of thiocyanate in ionic liquids. Recoveries of thiocyanate after spiking were 100.5%.
基金the NSFC(No.21173023)the 111 Project(No.B07012) in China and the TriFcM provided from professor Hua-Zhong Yu at Simon Fraser University in Canada
文摘The intramolecular electronic communication and multilevel ion-pairing effect of triferrocenylmethane（TriFcM） in organic phase was studied with the ＂thin-layer electrochemistry＂ approach.Three pairs of symmetric peaks in cyclic voltammetry of TriFcM correspond to three one-electron electrochemical reaction processes and indicate strong intramolecular electronic communication,which could be used to study the multilevel ion-pairing effect.Three different formation constants of ion-pairs between the three ferroceniums of TriFcM and perchlorate in thin organic film were obtained and compared.
文摘Investigation of amino acids in hydrothermal systems is of prime importance for the understanding of geochemistry and microbiology of hydrothermal vents and plumes, for carbon and metals global cycles, for metabolism of some hydrothermal microorganisms and for the origin of life issue. Extensive theoretical and experimental work on amino acids behaviour in hydrothermal fluids has been done, conversely only few data exist on natural samples. Because each hydrothermal vent is unique, the more data we collect the better we will be able to address each of these questions. Usually amino acids in hydrothermal fluids have been measured by HPLC-FLD. The chromatographic separation was at least 26 min and up to 135 min and the required derivatization step may be time consuming, may use harmful chemicals and may be source of contamination. Alternatively, we describe here a method combining quickness (4.5 min), high resolution (10,000), very low LOD (sub-ppb) and without derivatization. Characterisation and separation of 10 relevant proteinogenic underivatized amino acids was achieved by ion-pairing reversed-phase Ultra-high Performance Liquid Chromatography-Electrospray Ionisation-Quadrupole Time of Flight-Mass Spectrometry (UPLC-ESI-QTOF-MS). Excellent linearity in the response was obtained for all amino acids with correlation coefficients > 0.9921. This method was successfully applied to natural hydrothermal fluid samples from ultramafic-hosted vents of the Mid-Atlantic Ridge region. Results are consistent with the only 2 other studies published on ultramafic-hosted vents and complete the few available data.
基金supported by National Natural Science Foundation of China(No.20775070)Zhejiang Qianjiang Project of Science and Technology for Competent People(No.2008R10028)+1 种基金Zhejiang Provincial Natural Science Foundation of China(Nos.R4080124,Y4080064)Zhejiang Provincial Analysis and Testing Foundation of China(No.2007F70061)
文摘This paper proposes the use of novel surfactant additives for the separation of organic acids by ion-pair chromatography and studies the influences of surfactants on the chromatographic separation behaviors.Researches have been carried out on both silica gel matrix and polymer supporters in order to compare the two ordinary kinds of stationary phases,and the phenomenon is similar. Separation is based on differences in the stabilities of analyte-additive complexes in solution.Retention times of analytes can ...
文摘Enantiomers of four amino alcohols were resolved by ion-pair chromatography with (+)-10-camphorsulphonic acid as chiral counter ion. Studies of the influence of the mobile phase composition, the solute structure and the mobile phase flow-rate on separation are presented. Under the optimized conditions enantiomeric propanolol, norephedrine, metropolol and salbutamol were separated using dichloromethane-1-pentanol (97:3 v/v) as mobile phase on Lichrospher-100-DIOL column.
文摘The selected-state probabilities of collinear ion-pair formation process Na+I2→Na++I2-on Aten-Laming-Los two-State potential energy surface have been calculated by using LCAC-SW method. The results show that reaction probabilities are oscillatory with collision energy; the threshold energy of this ioniZation reaction is 2.8 ev, which is in modest agreement with experimental result.
基金Supported by the National Natural Science Foundation of China (Nos.20771006 and 20901004)
文摘A novel compound [Cl2Bz（3-MeQl） ]（TCNQ） （[Cl2Bz（3-MeQl） ]^＋ = 1-（3,4-dichlo-robenzyl） 3-methlquinoline cation,TCNQ-= 7,7,8,8-tetracyanoquinodimethanide anion） has been synthesized by the reaction of [Cl2Bz（3-MeQl） ]Br and LiTCNQ,and its structure was determined by single-crystal X-ray diffraction. The crystal belongs to monoclinic,space group P21/c. The structure analysis shows that the anions are stacked into a column with isolated π-dimers,and there is one type of TCNQ entries（TCNQ^-） ,in agreement with the IR spectra analysis and density functional theory calculations of the compound. The most prominent structural features are the completely segregated stacking columns of the TCNQ- anions and [Cl2Bz（3-MeQl）]＋ cations.
文摘The ion-pair compound [H2（teta）]^2＋·[Ni（CN）4]^2-·2H2O （C20H42N8NiO2, teta = meso- 5,7,7,12,14,14-hexamethyl- 1,4,8,11-tetraazacyclotetradecane） was synthesized and characterized by single-crystal X-ray diffraction. The crystal belongs to monoclinic, space group P211n with a = 10.0784（10）, b = 9.5411（7）, c = 14.1010（14）А, β= 106.752（2）°, V= 1298.4（2）A^3, Mr = 485.33, Z= 2, De= 1.241 g/cm^3,μ（MoKα） = 0.778 mm^-1 and F（000） = 524. The structure was refined to R = 0.0391 and wR = 0.0870 for 2614 observed reflections with I 〉 2σ（I）. The title compound contains one [Ni（CN）4]^2- anion, one protonated macrocyclic tetraamine cation [H2（teta）]^2＋ and two water molecules. There are multiform hydrogen bonds in the compound to link the different components and stabilize the crystal structure.
基金supported by the National Natural Science Foundation of China (No. 20371002, 20771006)
文摘The title compound [BrBzPy][TCNQ] （BrBzPy^＋=1-（4-bromobenzyl）pyridinium cation, TCNQ = 7,7,8,8-tetracyanoquinodimethanide anion） was synthesized by the reaction of [BrBzPy]Br and LiTCNQ in ethanol solution and its structure was determined by single-crystal X-ray diffraction. The crystal belongs to monoclinic, space group P21/c with a = 14.067（3）, b = 7.3089（14）, c = 23.796（4）A, β = 122.011（9）°, V= 2074.6（7）A^3, Z = 4, C24H15BrN5, Mr = 453.32, Dc = 1.451 g/cm^3,μ = 2.002 mm^-1, S = 1.047, F（000） = 916, R = 0.0398 and wR = 0.0921. The most prominent structural features are the completely segregated stacking columns of the TCNQ- anions and [BrBzPy]^＋ cations. In a TCNQ column, the centroid-to-centroid distances of the neighboring anions of TCNQ are 3.2693 and 4.9464 A, respectively.
基金Supported by the National Natural Science Foundation of China (No. 20771006)Natural Science Foundation of Anhui Province (No. 2006kj042a)Education Committee of Anhui Province (KJ2008B005)
文摘A novel compound [（CNBz）2Im]2（TCNQ）3（CH3CN）（（CNBz）2Im = 1,3-bis（4-cyano-benzyl） imidazole cation,TCNQ-1 = 7,7,8,8-tetracyanoquinodimethanide anion） was synthesized by the reaction of [（CNBz）2Im]Br and LiTCNQ in water and its structure was determined by single-crystal X-ray diffraction.The crystal belongs to monoclinic,space group P21/c with a = 10.1823（17）,b = 20.292（3）,c = 16.952（3） ,β = 104.73（0）°,V = 3387.6（10）3,Z = 4,C39H24N11,Mr = 646.69,Dc = 1.268 g/cm3,μ = 0.080 mm-1 and F（000） = 1340.The structure was solved by direct methods and refined to R = 0.0596 and wR = 0.0911 for 2690 observed reflections（Ⅰ 〉 2σ（Ⅰ））.The most prominent structural feature is that there are two types of TCNQ entries（TCNQ-1 and TCNQ0） in agreement with the IR spectra analysis of the compound.
基金Supported by the National Natural Science Foundation of China (No. 20371002)the Natural Science Foundation of Education Commission of Anhui Province (No. kj2007b092, kj2008b004)
文摘A novel ion-pair palladium（Ⅱ） compound, （NOzBzPy）2[Pd（dmit）2] （NO2BzPy^＋ = 1-（4-nitrobenzyl）pyridinium, dmit^2- = 2-thioxo-1,3-dithiole-4,5-bis（thiolate））, was synthesized and characterized by single-crystal X-ray structure determination. This compound crystallizes in the monoclinic system, space group P21/n with a = 10.4463（11）, b = 8.5627（9）, e = 20.017（2）A, β = 97.7730（10）°, V = 1774.1（3）A^3, Z = 2, C30H22N4O4S10Pd, Mr = 929.52, Dc = 1.740 g/cm^3,μ = 1.155 mm^-1, S = 1.006, F（000） = 936, R = 0.0354 and wR = 0.0675. The most intriguing general structural feature of the compound is the completely segregated columnar stacks of anions and cations. There exist hydrogen-bonding interactions within the cation column.
基金Supported by the grants of the National Natural Science Foundation of China (No. 20173032) and Ph.D. Special Research Foundation of the Chinese Education Department
文摘For the Li + I2 →Li+ + I2- system, theoretical study has been performed on the QCISD(T) level by using the ab initio method. The collision complex in ion-pair formation process was found and optimized. These results show that the crossed molecule beam (CMB) experimental phenomenon is verified and the detailed geometry is given for the first time. A mechanism for ion-pair formation was proposed in detail. The position where the collision complex occurs affects the reaction path. Specifically, the process has threshold when the collision complex appeared before the crossing point between the covalent and ionic state potential energy surfaces. On the contrary, the process has no threshold after the crossing point. Theoretically, the title system belongs to the former case.
基金supported by the National Natural Science Foundation of China(21706257,21878180)the Shanxi Province Coal Based Low-carbon Technology Major Projects(MC2016-05)the Xiangyuan Key Technology Research Projects(2018XYSDYY-02)。
文摘Lithium(Li)is an important energy metal in the 21st century.However,the selective recovery of Li is still a big challenge,especially from acidic solutions with multiple metal ions existence.Herein we report a new ion pair induced mechanism for selectively extracting Li^(+)from acidic chloride solutions by tributyl phosphate(TBP).It is shown that the acidity and the chloride ions in the aqueous phase have great effects on the extraction of Li^(+).The FT-IR,UV-Vis and ESI-MS experiments provide solid evidence for the formation of ion-pair complex[Li(TBP)_n(H_(2)O)_(m)]^(+)[FeCl_(4)]^(-)(n-1,2,3;m-0,1)in the organic phase,which brings about the effective and efficient extraction of Li^(+).This mechanism can overcome the Hofmeister bias and allow for the selective extraction of Li^(+) from the extremely hydrophilic chlorides.It has also been proved that the loaded Li in TBP can be effectively stripped by concentrated HCl solution with a Li/Fe separation factor>500.The understanding of the ion-pair transport mechanism is helpful for optimizing the recovery process or further advancing more efficient recovery techniques for Li from acidic liquor.
基金supported by the National Natural Science Foundation of China (No.21625301)
文摘Ion-pair dissociation is an important molecular process and frequently happens when the target molecule is pumped to its electronically superexcited states. In contrast to the experimental studies of photoexcitation ion-pair dissociation, there are some experimental challenges in the electron-impact ion-pair dissociation study, in particular, on determination of the energetic threshold. Here we report an experimental development for the ion-pair dissociation study by using the monochromized electron impacts. As an example, the threshold of BrCN→Br^-+CN^+ is determined as 13.78 eV according to the appearance energy of CN^+ signals, meanwhile, the time-sliced ion velocity image of CN^+ is recorded at 16.09 eV and indicates an anisotropic distribution of the CN^+ momentum.
