title: [Effect of solution pH value on the chelation structure of zinc acexamate by electrospray ionization mass spectrometry].
abstract: OBJECTIVE
  To study the effect of solution pH value on the chelation structure of zinc acexamate.
  
  
  METHODS
  A series of samples at different solution pH values were prepared by 10% HCl or 1 mol.L-1 NH3.H2O. Then API/TOFMS with electrospray ion source was applied to assay the samples. The nitrogen curtain gas and nebulizer gas were adjusted to a constant flow rate of 0.6 microL.min-1 and 2 microL.min-1 respectively. Samples were infused into the electrospray interface using a 500 microL syringe pump at a flow rate of 5 microL.min-1. Mass spectra were acquired in positive ion modes by scanning over the range of m/z 100-1,000.
  
  
  RESULTS
  The chelation structure of zinc acexamate is stable at pH 2.54 and it can be easy to form the ion (M + ZnY)+ (Y = CH3CONH(CH2)5COO-) and (2M + Na)+ in this condition.
  
  
  CONCLUSIONS
  The drug is an effective antiulcer agent. It may decrease the acidity of stomach juice, and form a polymer to protect the ulcer.
authors.affiliation: Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China.
authors.forename: C T
authors.initials: CT
authors.lastname: Yu
authors.forename: Y L
authors.initials: YL
authors.lastname: Guo
authors.forename: Z J
authors.initials: ZJ
authors.lastname: Zhang
authors.forename: B R
authors.initials: BR
authors.lastname: Xiang
authors.forename: D K
authors.initials: DK
authors.lastname: An
mesh_terms: D000614:Aminocaproates; D015119:Aminocaproic Acid / Q000737:chemistry*; D000897:Anti-Ulcer Agents / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D012996:Solutions; D021241:Spectrometry, Mass, Electrospray Ionization; D013329:Structure-Activity Relationship
chemical_list: D000614:Aminocaproates; D000897:Anti-Ulcer Agents; D012996:Solutions; C018802:6-acetylaminocaproic acid; D015119:Aminocaproic Acid