Low-flow inductively coupled plasma optical emission spectrometry is applied for the analysis of water-soluble LaF3nanocrystals doped with different lanthanide ions (Ce3+, Eu3+, Ho3+, Tb3+) for the first time. Colloidal solutions of citrate-stabilized nanoparticles (mean size 24 nm) were directly introduced into the plasma and no significant differences to digested particles were observed. The low-flow approach reduced the argon consumption of conventional instrumentation by 95% and provided limits of detection (LOD) for rare earth elements in the low microgram-per-liter range (Eu: 0.08 µg L−1, Ho: 0.18 µg L−1, La: 0.36 µg L−1, Tb: 0.56 µg L−1, Ce: 3.14 µg L−1). Relative standard deviations (RSDs) in the range of 1–2.2% with pneumatic sample introduction were obtained. The analytical performance of the low-flow torch was assessed by direct comparison with a conventional torch. Recoveries in the range of 97–104% were observed for most elements.