Abstract: The present invention relates to a novel method to determine the ratio of 5-methoxy and 6-methoxy isomers of omeprazole present in a mixture thereof. The method uses different Raman scattering efficiency values for the 5-methoxy and 6-methoxy isomers. This is of importance since the two isomers have different stability in the solid state in bulk form and in admixture with pharmaceutical excipients.

Abstract: A device and a method are intended for use in a spectroscopic analysis, especially performed with the aid of Raman spectroscopy, of a solid sample, such as a tablet (1). By means of a sample holder (7), the sample (1) is positioned in relation to an excitation beam which, during implementation of the analysis, falls upon a reception surface of the sample (1), the impingement area (S) being smaller than the reception surface of the sample (1). The sample holder (7) is rotated about an axis of rotation (A) parallel to the excitation beam, such that the point of impingement (S) of the excitation beam describes an annular scanning trace (20) on the reception surface of the sample (1). During implementation of the analysis, the radius of the annular scanning trace (20) is varied to enable a fairly large volume of the sample to be analysed.