title: [NMR studies on cetirizine hydrochloride].
abstract: OBJECTIVE
  To study the NMR phenomena of cetirizine hydrochloride and assign all proton and carbon signals in NMR spectra.
  
  
  METHODS
  To record the 1D and 2D NMR spectra of cetirizine hydrochloride while changing the experimental temperature and adding D2O into the solution.
  
  
  RESULTS
  More than one NMR signal or broad peak resulting from piperazine and the attached groups with N atom were given in DMSO-d6 solution at room temperature. "Coalescence" or narrowing had occurred for the proton and carbon signals when the experimental temperature was increased or D2O was added into the solution.
  
  
  CONCLUSIONS
  Compared with the NMR "time scale", there are more than one conformation of cetirizine hydrochloride in DMSO-d6 solution at room temperature. The different conformation will be exchanged fast while temperature rise and the stable conformation will be existed while D2O was added into the solution.
authors.affiliation: Center for Instrumental Analysis, China Pharmaceutical University, Nanjing 210009, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Li
authors.forename: Wen-bin
authors.initials: WB
authors.lastname: Shen
authors.forename: Qiao-gen
authors.initials: QG
authors.lastname: Zou
mesh_terms: D017332:Cetirizine / Q000737:chemistry*; D003903:Deuterium; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D011487:Protein Conformation; D013696:Temperature
chemical_list: D003903:Deuterium; D017332:Cetirizine