About detectability and limits of detection in single particle inductively coupled plasma mass spectrometry

Single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) offers unique features for the detection of particles, as well as for their quantification and size characterization. The detection capabilities of SP-ICP-MS are therefore not only limited to the concentration domains (of particles and dissolved related species), but also to the mass of element per particle and particle size domains. Discrimination and detection of particle events, based on the use of robust limits of decision (also known as critical values), and the estimation of the limits of detection in the different domains, require standardized metrological approaches that have not been clearly established yet. As a consequence, harmonized approaches and expressions to allow reliable comparisons between methods and instruments, as well as to process SP-ICP-MS data, are required. This paper is an attempt to summarize and review the different approaches applied up to now in relation to the detectability in SP-ICP-MS, and highlight the peculiarities of this topic in SP-ICP-MS. A holistic approach with criteria and expressions for the estimation of the different critical values and limits of detection in terms of the different instrumental and experimental parameters involved is proposed. Additionally, a calculation tool for estimating and predicting critical values and limits of detection under different experimental conditions is also included.