Levocetirizine Dihydrochloride - Impurity I (EP/BP), (-)-1-[(4-Chlorophenyl)phenylmethyl]piperazine, (R)-1-(p-Chlorobenzhydryl)piperazine, Chlorobenzhydryl Piperazine, (R)-1-[(4-Chlorophenyl)phenylmethyl]piperazine