Analytical Studies of some Pharmaceutical Compounds Containing Piperazine Ring

Piperazine Ring:Analytical Studies a) Reaction With Rose Bengal:Rose bengal reacts with the studied piperazine derivative to give apink colour exhibit maximum absorption at 575 nm Fig (37 - 42) .The ionpair formed is freely soluble in distilled water, therefore it can be directly measured without extraction process.Investigations were carried out to establish the most favourable conditions for the ion pair formation of the cited drugs with rose bengal to achieve maximum color development. The influence of some variables on the reaction has been tested and applied in general procedure.The effect of rose bengal concentration was studied. It was foundthat 1 ml of 0.1% of rose bengal was found to be sufficient to obtainmaximum absorbance in case of Cetirizine and Cinnarizine while 2 mlwas recommended to obtain maximum intensity for Hydroxyzine and 3ml for the other drugs, Fig (53, 54).The colour intensity was achieved without using buffer solution, addition of buffer decreases the colour intensity. The effect of temperature was studied on the ion pair formation. It was found that the reaction proceed quantitatively at room temperature,Fig (57,58). The effect of reaction time was also studied, 10 min were sufficient to produce maximum colour intensity, Fig (55, 56). The pink colour was found to be stable for at least three days