• Archives of Pharmacal Research
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• v.13 no.2
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• pp.174-179
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• 1990

Second derivative (D2) spectrometry using ion-pair extraction technique was development for the determination of total glycyrrhetic acid (GA) in Glycyrrhizae Radix, Glycyr-rhizin (G) obtained from Glycyrrhizae Radix was hydrolyzed into GA in 2 N-HCI and methanol (1:1) and extracted from aqueous phase in the form of an ion-pair complex with tetrapentylammonium bromide (TPA) as a counter ion. Maximum D2 amplitude (Z value) was obtained when 1000-fold or greater molar ratio of TPA was used at pH 11. Reaction an effective extraction solvent of the ion-pair complex. The linearity of standard curve of ion-pair GA was obtained in the range of 4.120 $\mu$g/ml as GA. Assayed contents of GA in dry powder by D2 UV spectrometry and HPLC method were 5.31 $\pm$ 0.04% and 5.20 $\pm$ 0.008%, respectively.

• Journal of Photoscience
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• v.8 no.1
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• pp.33-37
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• 2001

Picosecond absorption spectroscopy has been employed in the study of the solvent dynamics of 1, 2, 4, 5-tetracyanobenzene/biphenyl derivative radical ion pairs, and the resulting rates of radical ion pair separation are faster in acetonitrile than in dichloromethane. In an effort to account quantitatively for such solvent effect on the rate of radical ion pair separation, an equation for the rate of radical ion pair separation is introduced, in which the rate depends exponentially on the electrostatic interaction energy in the radical ion pair. In our analysis of the types of electrostatic interaction energy based on the conducting spheres in dielectric continuum was chosen, and the rate equation employing this electrostatic energy provided information on the distance on the distance of radical ion pair separation and solvation energy of the radical ion pair, thereby providing quantitative explanation for the observed solvent effect on the rate of radical ion pair sepaaration.

• Mass Spectrometry Letters
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• v.1 no.1
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• pp.9-12
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• 2010

Trimethylboroxine (TMB) is a six-membered ring compound containing Lewis acidic boron and Lewis basic oxygen atoms that can bind halide anion and alkali metal cation, respectively. We employed Fourier transform ion cyclotron resonance spectroscopy to study the gas-phase binding of $LiBrLi^+$ and $F^-(KF)_2$ to TMB. TMB forms association complexes with both $LiBrLi^+$ and $F^-(KF)_2$ at room temperature, providing direct evidence for the ditopic binding. Interestingly, the $TMB{\cdot}F^-(KF)_2$ anion complex is formed 33 times faster than the $TMB{\cdot}Li^+BrLi$ cation complex. To gain insight into the ditopic binding of an ion pair, we examined the structures and energetics of $TMB{\cdot}Li^+$, $TMB{\cdot}F^-$, $TMB{\cdot}LiF$ (the contact ion pair), and $Li^+{\cdot}TMB{\cdot}F^-$ (the separated ion pair) using Hartree-Fock and density functional theory. Theory suggests that $F^-$ binds more strongly to TMB than $Li^+$ and the contact ion-pair binding ($TMB{\cdot}LiF$) is more stable than the separated ion-pair binding ($Li^+{\cdot}TMB{\cdot}F^-$).

• Bulletin of the Korean Chemical Society
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• v.21 no.3
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• pp.358-360
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• 2000

• Bulletin of the Korean Chemical Society
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• v.28 no.2
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• pp.183-187
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• 2007

A simple and sensitive extractive spectrophotometric method has been described for the determination of buprenorphine either in raw material or in pharmaceutical formulations. The developed method is based on the formation of a colored ion-pair complex (1 : 1 drug/dye) of buprenorphine and bromocresol green (BCG) in buffer pH 3 and extracting in chloroform. The extracted complex shows absorbance maxima at 415 nm. Beer's law is obeyed in the concentration range of 1.32-100.81 μ g mL-1. The proposed method has been applied successfully for the determination of drug in commercial sublingual tablets and injectable dosage form. No significant interference was observed from the excipients commonly used as pharmaceutical aids with the assay procedure.

• YAKHAK HOEJI
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• v.18 no.2
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• pp.133-144
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• 1974

The metal indicator, acidic azo dyes NN, EBT and Calcon are utilized to analyse quantitatively chlorpheniramine, tripelenamine and diphenhydramine forming insoluble ion pair in aqueous solution at proper pH values between the acidic azo dyes and the sample molecules, these compexes are extracted by organic polar solvents, and organic layer is determined spectrophotometrically. Generally, the absorption maxima of the complexes are shifted to longer wavelengths compare to the absorption maxima of the dyes themselves. The binding ratio of the ion pair forming complex molecules in chloroform soln, are as follows ; NN-antihistamines (chlorpheniramine, tripelennamine, diphenhydramine) are NN-1 to antihisamine-1, EBT-antihistamines are EBT-2 to antithistamines a and Calcon-antihistamines are Calcon-3 to antithistamines-1. These coomplexes in chloroform soln. are very stable, and show higher absorbance than the other organic polar solvents. The binding state of complexes were presumed intermolecular hydrogen bond by their infrared spectra. In the mixture solution of three samples, the aqueous phase is buffered at pH 1.0, and benzene is used to extract ion pair of diphenhydramine EBT complex selectively. At pH 1.0 of aqueous layer, Calon-diphenhydramine complex is also extracted selectively by benzene. However, in this case very small amount of chlorpheniramine-calcon calcon simultaneously. The binding state of diphenhydramine-EBT and diphenhydramine-calcon in benzene are smae as the complexes in chloroform. But the absorption maxima of the complexes in benzene are shifted to shorter wavelenlgths than the complexes in chloroform.

• Archives of Pharmacal Research
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• v.9 no.1
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• pp.49-54
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• 1986

Effect of sodium taurodeoxycholate (TDC) infused intravenously on the pharmacokinetics of methylene blue (MB) was studied in the rat to investigate the role of ion-pair complexation in the body on drug elimination and disposition. Distribution volume (Vd) of MB was increased significantly (p< 0.05) by TDC infusion. Considering together with the fact that apparent partition coefficient (APC) of MB between phosphate buffer (pH 7.4) and n-octanol was increased markedly by TDC, the increase in Vd seemed to be the result of decreased polarity of MB by ion-pair formation with TDC. But total body clearance (CLt) and biliary excretion clearance (CLbil) of MB were not increased significantly by TDC.

• Journal of the Korean Chemical Society
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• v.26 no.5
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• pp.326-332
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• 1982

The structure of the complex extracted from an aqueous solution containing methylene blue and tetrafluoroborate with 1,2-dichloroethane has been investigated by comparing IR spectrum of the extract with those of pure components and appeared to be an 1 : 1 contact ion-pair between monovalent ions of opposite charge. The extraction constant obtained from the absorbance data measured at 658nm in 1,2-dichlorethane has a value of 1.1${\times}$at$10^4M{-1}$ 25$^{\circ}$C in the range from 1.43${\times}10^{-2}$ to 2.86${\times}10^{-1}$M HF. In the solvent extraction with nitrobenzene, the identical experiments show that extraction constants are increased with HF concentration possibly due to dissociation of the ion-pair in nitrobenzene.

• Journal of the Korean Chemical Society
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• v.27 no.6
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• pp.411-418
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• 1983

The effects of existing anions in hydrofluoric acid solutions, $F^-$ and $HF_2$on the extraction of methylene blue-$BF_4^-$ ion-pair into 1,2-dichloroethane have been investigated by spectrophotometry. The absorbance of the extracted ion-pair is found to be independent of $F^-$ion up to $10^{-2}$ molar concentration, which implies that $F^-$ion dose not directly interfere with the extraction. However, $HF_2^-$ ion competes with $BF_4^-$ion for methylene blue and the extraction constant for methylene blue-H$F_2$ion-pair is calculated to be 8.5 at $25^{\circ}C$.

• Bulletin of the Korean Chemical Society
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• v.17 no.10
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• pp.949-951
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• 1996