APPLICATION OF XANTHENE DERIVATIVES FOR ANALYTICAL-CHEMISTRY .83. SPECTROPHOTOMETRIC DETERMINATION OF CHLORHEXIDINE BASED ON A HYDROPHOBIC INTERACTION WITH THE ORTHO-HYDROXYHYDROQUINONEPHTHALEIN-MANGANESE(II) COMPLEX

A simple spectrophotometric method has been established for the determination of chlorhexidine (CH) with the o-hydroxyhydroquinonephthalein(QP)-manganese(II) complex. The apparent molar absorptivity and relative standard deviation for 50.6 μg of CH were 5.88×1041 mol-1 cm-1 and 0.47% (n=8), respectively. This method was applied to the determination of CH in a wide variety of pharmaceutical preparations with satisfactory analytical results. From the thermodynamic parameters (Δ5.49 kcal mol-1, Δ=0.04 kcal mol-1 and ΔS=18.60 cal mol-1 K-1) obtained from a van't Hoff plot, the binding between CH and the QP-manganese(II) complex was presumed to be a hydrophobic interaction. © 1990, The Japan Society for Analytical Chemistry. All rights reserved.