Tropical Journal of Pharmaceutical Research
Official Journal of Pharmacotherpy Group
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Evaluation of Dimethylformamide (DMF) as an Organic Modifier in Hydrophobicity Index (R_m) Determination

Olakunle S Idowu^†, Adedigbo A Fasanmade and Ajibola A Olaniyi

Tropical Journal of Pharmaceutical Research 2002; 1(2): 83-89

Abstract  Full Text

Purpose: Ideal behaviour of mixtures of organic modifier and water is reflected by a linear relationship between refractive index and fraction of organic modifier in the mixture. This study was carried out to investigate dimethylformamide (DMF) as an organic modifier in hydrophobicity index (R_m) determination.

Method: We quantitatively evaluated the problem of partial miscibility of phases associated with the reversed phase thin layer chromatographic (RPTLC) system, using liquid paraffin as stationary phase and acetone/water mixtures as mobile phase. Ideality of behaviour of acetone /water mixtures was investigated by refractive index measurements. R_m values of compounds were determined using mixtures of acetone and water as mobile phase.

Results: DMF/water mixture behaved ideally across the whole concentration range investigated (0-100%) while acetone/water mixture deviated from ideal behaviour when the concentration of acetone in the mixture was 80%.  DMF also gave a better extrapolation of R_m value from linear regression of partition data than acetone for bezafibrate used as a test-drug molecule.

Conclusion: DMF is a better organic modifier than acetone in this RPTLC system. These findings could be extended to drug-receptor and drug design studies. The use of dimethylformamide (DMF) in preference to acetone as organic modifier is proposed in this study.

Keywords: Drug design, dimethylformamide, hydrophobicity index, organic modifiers

^†To whom correspondence should be addressed:  E-mail:  olakunleid@yahoo.com  Tel: + 234 802 309 4981