title: [Detection of crystal polymorphs of nateglinide by DSC].
abstract: OBJECTIVE
  To establish the differential scanning calorimetric (DSC) methodology for controlling the crystal-type B form of nateglinide.
  
  
  METHODS
  Accurately weighed pure dried (P2O5 as desiccant for 4 h at 80 degrees C in vacuum) fine powder of crystal-type B and H of nateglinide were measured dQ/dT by DSC at heating rate of 10 degrees C. min-1 and temperature between 100 degrees C and 200 degrees C to calculate the enthalpy delta HB and delta HH. Accurately weight a series of uniform mixtures of crystal-type B and H of dried fine powder of nateglinide in different proportions. The enthalpy of the mixtures is measured by DSC as above to calculate the enthalpy (sigma delta H). Using B% as X, sigma delta H as Y, the regression equation was obtained. According to this equation, the unknown composition of mixed crystal was evaluated by the sigma delta H values. The method was used to control the limitation of crystal-type B of nateglinide by the sigma delta H value of mixture of known composition as reference.
  
  
  RESULTS
  The results measured from different laboratories showed that the repeatability was 0.61% and the recoveries were 86.2%-127% when the amounts of crystal-type B were between 0-15%.
  
  
  CONCLUSIONS
  This method can be used to evaluate the crystal-type B composition of nateglinide.
authors.affiliation: China Pharmaceutical University, Nanjing 210009, China.
authors.forename: Ke-jiang
authors.initials: KJ
authors.lastname: Lin
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.forename: Qi-dong
authors.initials: QD
authors.lastname: You
mesh_terms: D002152:Calorimetry, Differential Scanning; D003460:Crystallization; D003510:Cyclohexanes / Q000737:chemistry*; D000077715:Nateglinide; D010649:Phenylalanine / Q000031:analogs & derivatives* / Q000737:chemistry*; D011786:Quality Control
chemical_list: D003510:Cyclohexanes; D000077715:Nateglinide; D010649:Phenylalanine