Rapid quantitative analysis of urinary nicotine metabolites <i>via</i> a high-performance nanoconcentrator

Tobacco use is a widespread public health issue. The detection of smoke metabolites in body fluids using <i>in vitro</i> assays can offer a rapid, efficient and non-invasive approach to measure human exposure to smoke and assess its associated health risks, enabling the development of more impactful follow-up strategies. In this study, we prepared a high-performance nanoconcentrator to construct a rapid magnetic response-based integrated enrichment and detection platform, ELDI-TOF-MS, for the purpose of enriching nicotine metabolites in conjunction with successive LDI-TOF-MS analysis. Concurrently functioning as both a pre-enrichment unit and an LDI-TOF-MS matrix, the nanoconcentrator possesses a number of advantageous properties, including a rapid magnetic response within 1 s, a substantial specific surface area as high as 862 m² g^-1, high UV-vis absorption capacity, and high reproducibility in MS analysis. With these advantages, the nanoconcentrator-based ELDI-TOF-MS platform demonstrates high sensitivity and linearity for low concentration samples, rendering it suitable for both qualitative and quantitative analysis. Also, ELDI-TOF-MS responds to samples at low concentrations down to 2.5 ng mL^-1. For the analysis of two metabolites of nicotine, cotinine and norcotinine, the concentrations can be enriched by 2700 and 260 times. Furthermore, the rapid and efficient process facilitates batch analysis of up to 20 samples, with each batch requiring only 40 min. It is anticipated that the platform will enhance clinical efforts to detect nicotine use and augment the depth and breadth of testing.