Transfer of active pharmaceutical ingredients (API) Raman library from bench top towards handheld spectrometers

Over the last few years, manufacturers have made progress miniaturizing Raman spectrometers and trying to meet the practical needs of the end-users for raw material and finished goods identification.
In this study, library transfer from a donor benchtop Raman towards different Raman receiver devices, benchtop and handheld, was evaluated. The aim was to create a library of active pharmaceutical ingredients (API) on a lab spectrometer and to show that a transfer to different Raman systems using the Hit Quality Index (HQI) algorithm is possible. Consequently, library creation would be faster as well as the set-up of a device for routine measurements avoiding the acquisition of hundreds sample on each system, and allow optimizing method update strategy.
A donor benchtop DXR SmartRaman (Thermo Fisher Scientific®) and receivers composed of a benchtop RXN1 (Kaiser Optical System®), and two handheld spectrometers respectively Truscan (Thermo Fisher Scientific®) and MIRA M-1 (Metrohm AG®) were selected. All spectrometers were equipped with a 785 nm near infrared excitation laser to avoid variation in laser differences.
The Orbital-Raster-Scanning (ORS) technology available on the MIRA M-1 was initially evaluated. Understanding the effect of the ORS technique on APIs was a previous step before setting up a database transfer experiment. Subsequently, acetaminophen was used for library standardization to calibrate the x-axis of the Raman spectrometers. Finally, Raman spectra were pre-processed prior to computation of the HQI method.
The results showed that transferring an API library from a benchtop Raman system towards handheld systems with HQI values higher than 90% is possible. Additionally, an HQI of maximum 75% was observed between the different APIs suggesting that the APIs were different enough allowing a transfer.