Deep UV Laser-Induced Fluorescence for Pharmaceutical Cleaning Validation

Cleaning verification and validation is a requirement in the pharmaceutical industry. Due to the limited number of mobile devices that do effective and accurate onsite cleaning verification, it is mostly done via lab-based quality control techniques. These techniques, such as high-performance liquid chromatography (HPLC) or total organic carbon, often lead to extending the validation of cleaning by days. The void of more sensitive, accurate, and portable instruments to verify cleaning onsite has to be filled. The article discusses the use of deep ultra violet (DUV) laser-induced fluorescence for detecting carryover of active pharmaceutical ingredients (APIs) and detergents onsite. A modified spectrometer was used as an offsite bench type prototype for analyzing trace samples of API and cleaning detergents with various substrates. Even if the API to be detected has a low fluorescence efficiency, the specificity of the technique allows API traces having concentrations as low as ≈0.20 μg/cm² to be identified. The work also shows the possibility of using a probe for validating cleaning of hard to reach areas using DUV laser-induced fluorescence. DUV laser-induced fluorescence of trace API over any polymer/glass substrate has better signal to background ratio (SBR) compared to FTIR absorption techniques. Processing times of DUV laser-induced fluorescence trace detection are shown to be much less than swab based methods.