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Abstract
In isoperibol temperature-rise calorimetry, different approaches can lead to the corrected temperature rise. The description of the methodology, as well as an improvement in the approach to the accurate numerical calculation of the corrected temperature rise in isoperibol calorimetry, based on the comparison between the exponential functional description of the initial and final periods and an independent third order polynomial fitting, is presented. The latter is focused on the strategy of minimizing the result dependency on the definition of the main period of the reaction. Furthermore, the dedicated software application Labtermo is introduced.
The lipophilicity of thirty-seven N -[(4-arylpiperazin-1-yl)alkyl]-2-azaspiro[4.4]nonane-and [4.5]decane-1,3-dione derivatives has been determined by reversed-phase thin-layer chromatography with n -propanol-Tris buffer (pH 7.0) mixtures as mobile phases. All the compounds examined were basic molecules with calculated p K a values ranging from 6.20 to 8.95. Examination of the chromatographic behavior of the compounds revealed a linear correlation between corrected R M value ( R Mcorr ) and the concentration of n -propanol in the mobile phase. An extrapolation method was used for the estimation of relative retention parameters, R M 0 . The results obtained provided a good basis for evaluation of structure-lipophilicity relationships. The role of lipophilicity in the anticonvulsant activity of the set of compounds investigated is discussed: in general, the higher the value of R M 0 , the stronger the anticonvulsant efficacy.
Psychotropic drugs have been chromatographed on RP-18-HPTLC plates with mobile phases containing water, an organic modifier (methanol, dioxane, acetone, acetonitrile or tetrahydrofuran), and ion-pair reagents or ammonia. R F was measured for different concentrations of organic modifier. Relationships between solute retention and modifier concentration were described by the Soczewiński-Wachtmeister and Schoenmaker equations. The equations were used to determine R MW by the extrapolation method. Calculated values of R MW or C were correlated with log P values for the drugs, estimated by use of software. Significant correlations between the intercept ( R MW ) and slope ( S ) of the linear equations were also calculated. Chromatographic systems for which the R MW values obtained were close to calculated log P values can be used for determination of the lipophilicity of basic drugs.
. Shepherd, G. Machado, H.F. Medeiros and RJ. Sawaya. 2003. Comparing species richness among assemblages using sample units: why not use extrapolation methods to standardize different sample sizes? Oikos 101:398-410. Comparing
points on the exothermic regimes were selected for further calculations. The theoretical curing temperatures were obtained by T -β extrapolation method. To evaluate possible effects of the nano-TiO 2 on the curing properties of the polyester
the previously determined K e . The area under the plasma concentration vs. time curve from time zero to infinity (AUC 0– ∞ ) was calculated using WinNonlin® 4.2 via the linear trapezoidal rule and the standard area extrapolation method. The systemic
curves; all logk w values were calculated by the extrapolation method (correlation coefficients between logk and φ were from 0.9837 to 0.9999) For the development of HPLC method, C8 column was chosen due to the similarity of its hydrophobicity with
extrapolation method. In our case, the intersection of corrosion potential and the linear extrapolated to the cathodic branches of curves will give the corrosion current density values. Figure 7
Treatment of water-induced curvature of the DSC heat flow rate signal
Applied to fractionated nucleation of polypropylene dispersed in water
polymer, and providing a reasonable wide temperature range of the melt to extrapolate from. Finally, in order to verify the consistency of the proposed corrections, both methods were applied (in cooling by the “Extrapolation method” and heating by
( Nilsson – Brunet 2006 ). The disadvantage of the HP filter is the end-point bias that can be solved by predictions, for example, by applying the extrapolation method ( Kranendonk et al. 2004 ), as shown in this study. After removing the trend, the cyclical
