Development of Turbidimetric Methods for the Determination of Some N-Substituted Phenothiazine Derivatives Using Sodium Dodecyl Sulfate and Mercury(II) Chloride

Abstract

Two turbidimetric procedures were developed for the determination of Fluphenazine·HCl (FPH), Chlorpromazine·HCl (CPH), Thioridazine·HCl (TH), and Trifluophenazine·2HCl (TFPH) in several pharmaceutical preparations using sodium dodecyl sulfate (SDS) (method A) and HgCl₂ (method B) as precipitant reagents. Method A is based on the sparingly soluble ion-association complex formation between protonated phenothiazines and SDS. In method B, HgCl₂ is reduced to insoluble Hg₂Cl₂ in the presence of phenothiazine derivatives. The Beer's law in method A was obeyed over the range 30–71.5, 14–106, and 8–57 µg mL⁻¹ for CPH, FPH, and TH, respectively. TFPH, CPH, and TH were determined using method B over the range 14.4–191.7, 17.7–106.6, and 1–8.1 µg mL⁻¹, respectively. The proposed methods are simple, fast, precise, economical, and applicable for the determination of selected phenothiazine drugs in formulations at a wide concentration range without any considerable interference.

Keywords:

• Phenothiazines determination
• Turbidimetry
• Sodium dodecyl sulfate
• Hg(II) chloride

Acknowledgments

Financial support from the Research Affairs of Urmia University is acknowledged. The authors are grateful to the TEHRAN-SHIMI and PARS-MINOO Pharmaceutical Companies, Tehran, Iran for the supply of pure drug samples.