## 2 Methods for Determination of Lipophilicity
### Indirect Experimental Determination of Lipophilicity
#### 2.3.2 Reversed-Phase High-Performance Liquid Chromatography
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Analytes** & **Aim** & **Chromotographic** & **Chromotographic Conditions** & **Ref.** \\ \hline \multirow{6}{*}{Acridinone derivatives} & & & Columns: Luna 5u C18(2) (150 \(\times\) 4.6 mm, 5 \(\upmu\)m), \\  & & & Candeza CD-C18 (150 \(\times\) 4.6 mm, 3 \(\upmu\)m), TSK-gel \\  & & & ODS-80 TS (150 \(\times\) 4.6 mm, 5 \(\upmu\)m), Asentis C18 \\  & & RP-HPLC/DAD & (150 \(\times\) 4.6 mm, 5 \(\upmu\)m), Unison UK-C18 \\  & & RP-HPLC & (254 nm) & (150 \(\times\) 4.6 mm, 3 \(\upmu\)m), Zorbax SB-C8 column \\  & & & (75 \(\times\) 4.6 mm, 3.5 \(\upmu\)m); MP: mixtures of ACN or \\  & & & MeOH and water with 0.1\% of formic acid; \\  & & & FR: 1.0 mL/min \\ \hline \multirow{6}{*}{Neutral drugs} & Development of a method to determine the lipophilicity by & RP-HPLC/DAD & Column: Supelcosil LC-ABZ (50 \(\times\) 4.6 mm, 5 \(\upmu\)m); MP: mixture of MeOH (15–70\%) and 20 mM MOPS \\  & & & buffer at pH 7.4 with 0.25\% of octanol; FR: 0.5, 1.0, \\  & & & or 2.0 mL/min \\ \hline \multirow{6}{*}{Structurally unrelated compounds} & Determine the lipophilicity by & Column: ODS2-IK5 Inertsil (150 \(\times\) 4.6 mm); MP: mixture of ACN (0–100\%) and 50 mM ammonium \\  & RP-HPLC with a fast generic & & acetate (pH ranging from 7.0 to 7.3); \\  & & gradient & FR: 1.0 mL/min \\ \hline \multirow{6}{*}{Drugs with diverse chemical nature} & Determine the lipophilicity by & \multirow{2}{*}{RP-HPLC/ UV-Vis} & Column: XBridgeTM Shield RP\({}_{18}\) (50 \(\times\) 4.6 mm, 5 \(\upmu\)m); MP: mixtures of MeOH (70 to 10\%) and 0.02 \\  & RP-HPLC & UV-Vis & M phosphate buffer at pH 7.0 with 1-octanol/buffer \\  & & & partitioning a 0.25\%; FR: 1.0 or 0.5 mL/min \\ \hline \multirow{2}{*}{\(1H\)-Pyrazolo[3,4- \(b\)]pyridine derivatives} & Determine the lipophilicity by & \multirow{2}{*}{RP-HPLC/ UV-Vis} & Column: LC8 SUPERLO (250 \(\times\) 4.6 mm \(\times\) 5\(\upmu\)m); MP: mixtures of ACN (40–65\%) and 0.1 M \\  & RP-TLC and & (254 nm) & phosphate buffer at pH 7.4; FR: 1.5 mL/min \\ \hline \multirow{2}{*}{Isochromanone derivatives} & Determine the  lipophilicity by & \multirow{2}{*}{RP-HPLC/DAD} & Column: Hypersi 5 MOS (250 \(\times\) 4.6 mm, 5 \(\upmu\)m); MP: mixture of ACN (40\%) and triethyl-ammonium \\  & RP-HPLC & & phosphate buffer; FR: 1.0 mL/min \\ \hline \multirow{6}{*}{Amphoteric compounds, amino acids, and small peptides} & Determine the  lipophilicity by & \multirow{2}{*}{RP-HPLC/ UV-Vis} & Column: Kromasil C18 (150 \(\times\) 4.6 mm, 5 \(\upmu\)m); MP: mixtures of MeOH (10–90\%) and ammonium \\  & & broad pH range & acetate buffer at different pH; FR: 1.0 mL/min \\ \hline \multirow{6}{*}{\(\alpha\)-(4-Phenylpiperazine) derivatives of \(N\)-benzylamides & Determine  lipophilicity by & \multirow{2}{*}{RP-HPLC/ UV-Vis} & Column: Lichrospher RP18, (125 \(\times\) 4.0 mm, 5 \(\upmu\)m); MP: mixtures of ACN (45–65\%) and water with \\  & RP-HPLC and in  silica methods & (215 nm) & addition of 0.1\%/TFA; FR: 1.0 mL/min \\ \hline \multirow{6}{*}{N-Alkylbenzenes and some OECD reference substances} & Correlate log P  shake-flask values & \multirow{2}{*}{RP-HPLC/ UV-Vis} & Column: C18-SIL-X-5 (250 \(\times\) 4.0 mm, 5 \(\upmu\)m); MP: mixtures of MeOH (60–95\%) and water; FR: 1.0 mL/min \\  & & factors derived from RP-HPLC & \\ \hline \multirow{6}{*}{Natural secondary plant metabolites} & Determine  lipophilicity by  RP-HPLC and in  silica methods & \multirow{2}{*}{RP-HPLC/DAD} & Column: GraceSmart RP18 (150 \(\times\) 4.6 mm, 5 \(\upmu\)m); MP: mixtures of MeOH (90–30\%) and 0.01 M  phosphate buffer at pH 2.0; FR: 1.0 mL/min \\ \cline{1-1}  & & & phosphate buffer at pH 2.0; FR: 1.0 mL/min \\ \hline \multirow{6}{*}{Derivatives of \(N\)-substituted amides of 3-(ethylthio-1,2,4- triazoleol-5-yl)propenoic acid} & Determine the  lipophilicity by  UV-Vis (254 nm) & RP-HPLC/  Column: RP-18 Waters Symmetry (150 \(\times\) 4.6 mm 5 \(\upmu\)m); MP: mixtures of MeOH (50–75\%) and water (254 nm) & Column: GraceSmart RP18 (150 \(\times\) 4.6 mm, 5 \(\upmu\)m); MP: mixtures of MeOH (90–30\%) and 0.01 M  phosphate buffer at pH 2.0; FR: 1.0 mL/min \\ \cline{1-1}  & & & phosphate buffer at pH 2.0; FR: 1.0 mL/min \\ \hline \hline \end{tabular}
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