SP-ICP-MS mass shift mode as an optimal strategy for characterizing titanium dioxide nanoparticles in urine and blood samples

• SP-ICP-MS with optimized mass shift mode accurately characterized TiO 2 NPs in human urine and blood samples. • Sufficiently small size detection limits more realistically reflect TiO 2 NPs exposure. • The most frequency size of TiO 2 NPs exposed in human urine and blood samples is in the range of 20–40 nm. • The method supports health risk assessment of TiO 2 NPs. Titanium dioxide nanoparticles (TiO 2 NPs), one of the five major types of NPs, are commonly used as synthetic materials. Effective monitoring of TiO 2 NPs requires accurate determination of both their size and NP concentration, which remains a significant challenge. This study investigates the application of single-particle inductively coupled plasma mass spectrometry (SP-ICP-MS) for the simultaneous characterization and quantification of TiO 2 NPs in biological samples. Mass shift technology based on SP-ICP-MS/MS was employed to characterize TiO 2 NPs in human whole blood, urine, and serum samples. Comprehensive evaluations were conducted on pretreatment conditions, instrument parameters, and validation methods. The optimized technique was applied to actual samples, which were dispersed using 1 % PVP-10 with ultrasonic treatment at 100 Hz. Instrument parameters were optimized as follows: ammonia gas flow rate of 0.6 L min −1 , dwell time of 100 μs, AFT voltage at 100 V, and Rpq value of 0.50. The Zeta potential of the dispersion system remained above (±) 30 mV, ensuring stability over a period of 0–120 min. The recovery of particle concentration across the three sample types ranged from 79.4 % to 117.5 %, while the dimensional verification results were satisfactory. The method demonstrated a size detection limit of 9 nm and a particle detection limit of 2.06 × 10 3 NPs mL −1 . These results validate the applicability of the methodology for human biomonitoring.