Differentiation of lactose sample batches from surface impurities by OrbiSIMS

Impurities present on the surface of pharmaceutical formulations for drug delivery significantly impact their stability and efficacy. Hence, the characterization of impurities on the surface is essential to ensure efficacy, quality, and safety. Secondary ion mass spectrometry (SIMS) is gaining increasing popularity for surface analysis in the pharmaceutical industry, due to its high sensitivity and spatial resolution. Time-of-Flight (ToF) SIMS instruments have been successfully used. However, their application has been limited since the mass resolving power and mass accuracy are too low to separate complex peaks and give identification with confidence. The OrbiSIMS instrument overcomes this issue owing to its Orbitrap analyzer with a mass resolving power of >240 000 at m/z 200 and a mass accuracy of <2 ppm. We use the OrbiSIMS in combination with multivariate analysis to differentiate notionally identical batches of lactose from different suppliers using the detection of small differences in surface impurities.