The analysis was run from 20 °C to a temperature AZD6244 datasheet above the melting point of the compound (Tm  ) while being purged with nitrogen gas (80 ml/min). No signs of residual solvents desorbing during heating was observed in the DSC signal. The presence of amorphous phase in the samples was judged from the occurrence of glass transition and exothermic crystallization peaks in the heat flow signal upon heating, alternatively

a complete absence of crystallization and melting peaks. The glass transition was determined from the mid-point of the step change in heat flow and the amorphous Libraries content of the spray-dried compounds was estimated from: equation(1) %Amorphous=ΔHcrΔH100where ΔHcr   is the enthalpy of crystallization and calculated from area under the crystallization peak in the thermogram, and ΔH   is the difference in enthalpy between the amorphous and crystalline state at the crystallization temperature

(Tcr  ), and given by equation(2) ΔH=ΔHm-∫TTmΔCpdTwhere ΔHm   is the melting enthalpy, Tm   the melting temperature and equation(3) ΔCp=Cpam-Cpcrwhere Cpam and Cpcr are the heat capacities of the amorphous and crystalline state, respectively. As an approximation, ΔCp can be assumed to be constant and selleck chemicals llc calculated according to Thompson and Spaepen (1979): equation(4) ΔCp=ΔHmTmwhere ΔHm and Tm is obtained from the DSC data. The solid state of the spray-dried material was further verified by X-ray Powder Diffraction analysis. Diffraction patterns were obtained by using a Kratzky camera with a linear position-sensitive wide angle detector (HECUS M. BRAUN X-ray Systems, Graz, Austria) detecting diffracted radiation in a 2θ interval from 17° to 25° (given by the limits of the detector) in steps of 0.01°. The radiation was generated by an Cu Kα X-ray generator Etomidate (Philips, PW 1830/40) working at 40 V and 50 A. The temperature was controlled to 25 °C by a Peltier element. Each sample was run for 15 min in vacuum. When the X-ray analysis showed a diffuse scattering pattern the sample was considered to be

predominantly amorphous, while samples generating diffraction patterns with distinctive peaks were considered to contain crystalline phase. The ability of the compounds to become amorphous when cooled from the pure liquid state was investigated by cooling melts of the drugs in the DSC. The experimental conditions were the same as for the analysis of spray-dried material, except that approximately 2 mg of unprocessed substance was weighed into the aluminium pans. The samples were analysed by performing two heating/cooling cycles, the first for melt-cooling and the second for analysis. During the first cycle the samples were heated from room temperature to approximately 10 °C above their Tm at a heating rate of 20 °C/min and immediately cooled at a rate of 40 °C/min.