Structure-making behaviour of L-arginine in aqueous solution of drug ketorolac tromethamine: volumetric, compressibility and viscometric studies

Abstract

<p>In this work, density <i>ρ</i>, speed of sound <i>u</i> and viscosity <i>η</i>, were measured for L-arginine in aqueous ketorolac tromethamine solutions at various temperatures (293.15, 298.15, 303.15, 308.15 and 313.15 K) and at atmospheric pressure. Apparent molar volume <i>V_Φ</i>, limiting apparent molar volume <i>V°_Φ</i>, limiting apparent molar volume of transfer <i>V°_Φ,tr</i>, limiting molar expansivity <i>E°_Φ</i>, Hepler’s constant <math><mrow><msub><mrow><mrow><mi>∂</mi><mn>2</mn></mrow><msub><mrow><mi>V</mi><mn>0</mn></mrow><mi>Φ</mi></msub><mrow><mo>/</mo></mrow><mi>∂</mi><mrow><mi>T</mi><mn>2</mn></mrow></mrow><mi>P</mi></msub></mrow></math>and hydration number <i>n_H</i> were obtained using density data. Apparent molar isentropic compression <i>K_Φ,S</i>, limiting apparent molar isentropic compression <i>K°_Φ,S</i>, limiting apparent molar isentropic compression of transfer <i>K°_Φ,S,tr</i> and hydration number <i>n_H</i> were obtained using speed of sound data. Jones–Dole coefficient-B <i>B</i>, viscosity B-coefficients of transfer <i>B_tr</i>, variation of <i>B</i> with temperature (<math><mi>d</mi><mi>B</mi><mrow><mo>/</mo></mrow><mi>d</mi><mi>T</mi></math>), free energy of activation of viscous flow per mole of solvent <i>Δμ°^#₂</i> and per mole of solute <i>Δμ°^#₁</i> were obtained from viscosity data. The obtained results are discussed in terms of solute–solvent interactions in these systems.</p