The Experts below are selected from a list of 177 Experts worldwide ranked by ideXlab platform
Marta Pluhařova - One of the best experts on this subject based on the ideXlab platform.
-
thermodynamic dissociation constants of codeine ethylmorphine and Homatropine by regression analysis of potentiometric titration data
Analytica Chimica Acta, 2000Co-Authors: Milan Meloun, Marta PluhařovaAbstract:Concentration and mixed dissociation constant(s) of three drug acids HJ L, codeine, ethylmorphine and Homatropine, at various ionic strengths I in the range of 0.03‐0.81 have been determined with the use of regression analysis of potentiometric titration data when common parameters(pKa;j , jD1, ::: , J), and group parameters(E 00 , L0, HT) are simultaneously refined. Reliability of the dissociation constant(s) should be proven because three group parameters ( E 00 , L0, HT) are ill-conditioned in the regression model and have influence on systematic error in the estimated p Ka. Internal calibrationof the glass electrode cell in the concentration (stoichiometric) scale [H C ] performed during titration was used. The thermodynamic dissociation constant pK T a , an ill-conditioned ion-size parameter a [10 8 m] and the salting-out coefficient C were estimated by nonlinear regression of fpKa, Ig data. Goodness-of-fit tests provide various regression diagnostics enabling the reliability of parameters at 25C to be proven. For codeine pK T a D8.310.01, aD41 [10 8 m], CD0.450.04; for ethylmorphine pK T a D8.170.01, aD82 [10 8 m], CD0.540.03; and for Homatropine pK T D9.900.01, aD62 [10 8 m], CD0.510.03. © 2000 Elsevier Science B.V. All rights reserved.
Milan Meloun - One of the best experts on this subject based on the ideXlab platform.
-
Thermodynamic dissociation constants of codeine ethylmorphine and Homatropine by regression analysis of potentiometric titration data, Anal
2015Co-Authors: Milan MelounAbstract:Concentration and mixed dissociation constant(s) of three drug acids HJ L, codeine, ethylmorphine and Homatropine, at various ionic strengths I in the range of 0.03–0.81 have been determined with the use of regression analysis of potentiometric titration data when common parameters (pKa;j, jD1, : : : , J), and group parameters (E00, L0, HT) are simultaneously refined. Reliability of the dissociation constant(s) should be proven because three group parameters (E00, L0, HT) are ill-conditioned in the regression model and have influence on systematic error in the estimated pKa. Internal calibration of the glass electrode cell in the concentration (stoichiometric) scale [HC] performed during titration was used. The thermodynamic dissociation constant pKTa, an ill-conditioned ion-size parameter å [10−8 m] and the salting-out coefficient C were estimated by nonlinear regression of fpKa, Ig data. Goodness-of-fit tests provide various regression diagnostics enabling the reliability of parameters at 25C to be proven. For codeine pKTa D8.310.01, åD41 [10−8 m], CD0.450.04; for ethylmorphine pKTa D8.170.01, åD82 [10−8 m], CD0.540.03; and for Homatropine pKTa D9.900.01, åD62 [10−8 m], CD0.510.03. © 2000 Elsevie
-
thermodynamic dissociation constants of codeine ethylmorphine and Homatropine by regression analysis of potentiometric titration data
Analytica Chimica Acta, 2000Co-Authors: Milan Meloun, Marta PluhařovaAbstract:Concentration and mixed dissociation constant(s) of three drug acids HJ L, codeine, ethylmorphine and Homatropine, at various ionic strengths I in the range of 0.03‐0.81 have been determined with the use of regression analysis of potentiometric titration data when common parameters(pKa;j , jD1, ::: , J), and group parameters(E 00 , L0, HT) are simultaneously refined. Reliability of the dissociation constant(s) should be proven because three group parameters ( E 00 , L0, HT) are ill-conditioned in the regression model and have influence on systematic error in the estimated p Ka. Internal calibrationof the glass electrode cell in the concentration (stoichiometric) scale [H C ] performed during titration was used. The thermodynamic dissociation constant pK T a , an ill-conditioned ion-size parameter a [10 8 m] and the salting-out coefficient C were estimated by nonlinear regression of fpKa, Ig data. Goodness-of-fit tests provide various regression diagnostics enabling the reliability of parameters at 25C to be proven. For codeine pK T a D8.310.01, aD41 [10 8 m], CD0.450.04; for ethylmorphine pK T a D8.170.01, aD82 [10 8 m], CD0.540.03; and for Homatropine pK T D9.900.01, aD62 [10 8 m], CD0.510.03. © 2000 Elsevier Science B.V. All rights reserved.
Yubing Tang - One of the best experts on this subject based on the ideXlab platform.
-
significance of mobile phase composition in enantioseparation of chiral drugs by hplc on a cellulose based chiral stationary phase
Chirality, 1996Co-Authors: Yubing TangAbstract:Eight randomly selected pharmaceuticals, which included ibuprofen, ketoprofen, albuterol, acebutolol, propafenone, betaxolol, methylphenidate, and Homatropine, were directly separated on a cellulose tris(4-methylbenzoate) chiral stationary phase (CSP) without derivatization via normal phase mode HPLC. Enantioresolution was achieved by the optimization of the type and the ratio of mobile phase modifiers and additives. The modifiers included alcohols; the mobile phase additives were trifluoroacetic acid (TFA) and triethylamine (TEA). It was found that methanol and ethanol were superior to isopropanol as mobile phase modifiers for enhancing chiral separation of some of the chiral drugs. The results also demonstrated that TFA has a dominant effect on chiral separations for both acidic and basic chiral drugs, although for some basic drug such as Homatropine, TEA was more beneficial at improving enantioseparation. The separation of acebutolol enantiomers was achieved for the first time by adding both TFA and TEA to the mobile phase. The purpose of this paper is to demonstrate that the applicability of cellulose based CSPs can be expanded by controlling the mobile phase compositions through the addition of trace amounts of achiral additives and the selection of the appropriate alcoholic modifier. © 1996 Wiley-Liss, Inc.
Sam Fong Yau Li - One of the best experts on this subject based on the ideXlab platform.
-
Chiral resolution of atropine, Homatropine and eight synthetic tropinyl and piperidinyl esters by capillary zone electrophoresis with cyclodextrin additives.
Electrophoresis, 1999Co-Authors: Yan Wang, Mei Lin Go, Rong Xu, Sam Fong Yau LiAbstract:: Chiral resolution of atropine, Homatropine and eight synthetic tropinyl and piperidinyl esters were studied by capillary zone electrophoresis with cyclodextrin additives. Atropine and eight synthetic derivatives were successfully resolved by heptakis-(2,3,6-tri-O-methyl)-beta-cyclodextrin (TM-beta-CD) at concentrations ranging from 10 to 40 mM. Homatropine was baseline resolved by 10 mM beta-cyclodextrin and hydroxypropyl-beta-cyclodextrin (HP-beta-CD), respectively. The developed method was employed for the determination of atropine enantiomers in human serum.
Choudhry Rajan - One of the best experts on this subject based on the ideXlab platform.
-
status of cyclopentolate as a cycloplegic in children a comparison with atropine and Homatropine
Acta Ophthalmologica, 2009Co-Authors: A.k. Khurana, B. K. Ahluwalia, Choudhry RajanAbstract:: We compared the cycloplegic effects of cyclopentolate, Homatropine and atropine by the retinoscopy findings and residual accommodation left following their use in the same individual. The mean residual accommodation measured after the use of cyclopentolate, Homatropine and atropine was 1.48 +/- 0.33 D, 2.32 +/- 0.37 D and 1.10 D +/- 0.28 D, respectively, and the mean difference in retinoscopy readings between cyclopentolate and Homatropine, Homatropine and atropine, and atropine and cyclopentolate was 0.46 +/- 0.21, 0.71 +/- 0.23 and 0.26 +/- 0.14, respectively. We further observed that a tonus allowance of about +0.75 D would suffice for cyclopentolate. The merits for recommending cyclopentolate as a routine cycloplegic in children are discussed.