QUANTITATIVE FT-RAMAN ANALYSIS OF 2 CRYSTAL FORMS OF A PHARMACEUTICALCOMPOUND

A pharmaceutical active compound H appears in two polymorphs, A and B, that are stable below and above room temperature, respectively. The A - and B-forms were found to have distinct FT-Raman spectra, in particu lar for a band at 1716 cm(-1) (A-form) or 1724 cm(-1) (B-form). Mixtur es of A- in B-form were prepared, and the relative intensity of the ch aracteristic bands at 1716 and 1724 cm(-1) was found to be proportiona l to the relative amounts of A- and B-form in the mixtures. A calibrat ion was made which was linear in the range from 1.8 to 15.4% (w/w) of Ain B-form. The results were compared with other methods for analysis of polymorphs: FT-TR spectrometry, differential scanning calorimetry, and powder X-ray diffractometry. A novel FT-Raman sample presentation method for inhomogeneous samples is presented. (C) 1997 Elsevier Scien ce B.V.