Comparison of the Crystallinity of Imipenem Samples by X-ray Diffraction of Amorphous Material

The intensity of X‐rays diffracted by amorphous material in samples of the β‐lactam antibiotic imipenem [(5R, 6S)‐3‐[[2‐(formimidoyl‐amino)ethyl]thio]‐6‐[(R)‐1‐hydroxyethyl]‐7‐oxo‐1‐azabicyclo[3.2.0]hept‐2‐ene‐2‐carboxylic acid] was used to compare the crystallinity of the samples. The method makes use of the intensity in the X‐ray powder diffraction (XRPD) pattern at a diffraction angle of 28° (2Θ), at which no crystalline peaks are observed. A linear relationship (R2= 0.9999) exists between amorphous intensity and crystallinity for synthetic mixtures of amorphous and crystalline imipenem. Sample preparation techniques ordinarity used in XRPD experiments were utilized.