Raman-based detection of ciprofloxacin and its degradation in pharmaceutical formulations

A Raman-based label-free analytical method was developed to detect the antibiotic ciprofloxacin (CIP) in various pharmaceutical formulations in the presence of different matrices (e.g., ear drops, eye drops and infusion solutions). The Raman spectral analysis is performed for semiquantification in the case of a low background Raman signal, i.e., the signal originating from the excipient and carrier substance of the formulation does not interfere with the fingerprint spectrum of ciprofloxacin. In the case of a background spectrum rich in Raman modes originating from the excipient and carrier substance of the formulation, the pharmaceutical formulation is diluted 1:5000, and thus, the background signal is undetectable. Due to the high affinity of ciprofloxacin towards metallic surfaces, surface-enhanced Raman spectroscopy (SERS) is applied to allow for the sensitive detection of ciprofloxacin. Moreover, the developed measurement routine can be applied to monitor the degradation of the active component ciprofloxacin within the pharmaceutical formulation. The developed assay can therefore be extended to the pharmaceutical industry for quality control in assay applications or the preparation of individualized medicines.