SPCal - an open source, easy-to-use processing platform for ICP-TOFMS-based single event data

Single particle inductively coupled plasma-mass spectrometry (SP ICP-MS) has evolved into one of the most powerful techniques for the bottom-up characterisation of nanoparticle suspensions. The latest generation of time-of-flight mass analysers offers new perspectives on single particles by rapidly collecting full mass spectra and providing information on particle composition and abundances, even in unknown samples. However, SP ICP-TOFMS is associated with vast and complex data, which can hamper its applicability and the interrogation of specific particle features. Unlocking the full potential of SP ICP-TOFMS requires dedicated, easy-to-use software solutions to navigate through data sets and promote transparent, efficient and precise processing. SPCal is an open-source SP data processing platform, which we have previously released for quadrupole-based data. In this work, we expand its reach by additionally enabling the analysis of TOF-based SP data sets. We have incorporated various tools to facilitate the handling, manipulation and calibration of large data sets and provide the required statistical fundament and models to promote accurate thresholding. Non-target screening tools are integrated to pinpoint particulate elements in unknown samples without the requirement for a priori investigations or modelling. Next to basic functions like the calibration of size and mass distributions, methods to carry out cluster analysis (PCA, HAC) provide the means to study groups of particles based on their composition and conditional data filtering allows the interrogation of particle populations by selectecting specific features.