Normal-Phase High Performance Liquid Chromatographic Method with Dansylation for the Assay of Piperazine Citrate in Dosage Forms

Abstract

The assay of the anthelmintic agent piperazine citrate in dosage forms has been accomplished by normal-phase HPLC after converting the drug to a UV-absorbing dansyl (DNS) derivative. For this purpose, an aliquot of an aqueous extract or dilution from tablets, powders, effervescent granules or syrups was first mixed with a solution of 1-benzylpiperazine, the internal standard, and next with solutions of DNS-chloride and sodium carbonate. Sonication of the reaction mixture led to the formation of the DNS-derivatives, with bis-DNS-piperazine separating as a crystalline product. After extraction into chloroform, and dilution of the extract with mobile phase, the DNS derivatives were separated on a cyanopropyl column with hexane-isopropanol (85:15) as the mobile phase. At a flow rate of 1.5 mL/min and a detection wavelength of 335 nm, DNS-1-benzylpiperazine and bis-DNS piperazine eluted at 4.0 and 8.5 min, respectively. Detector responses were linearly related to on-column concentrations of piperazine citrate ranging from 8–50 μg. The recovery of analyte from synthetic formulations simulating the various dosage forms was in all cases > 99.0% (range 99.7–102.0%). Assay results by the proposed method agreed closely with those obtained by the gravimetric method of USP 23.