where, ηn is transport efficiency, Qsam is sample flow rate (mL
min‒1), tdwell is dwell time (ms per event), fNP is number of
nanoparticle (pulse per event). If the nanoparticle
concentration of standard sample is known, ηn can be
calculated based on Equation (1). C is analytical ionic element
calibration curve equation. According to Equation (2), the
mass flux equation W (mass per event) can be established.
Spulse is nanoparticle signal, Sbkgd is background signal.
Background signal includes instrument noise and signal from
dissolved ions. fm is the mass fraction of the analyte metal
nanoparticles. m is the slope of mass flux equation W.
Nanoparticle mass mNP is determined using Equation (3).
Assume the analytical nanoparticles are monodisperse and
spherical, the diameter of the nanoparticle dNP (nm) can be
determined using the nanoparticle mass (Equation (4)), where
ρ is the particle density (g cm‒3). Nanoparticle number
concentration can be calculated basing on Equation (1).