100% Efficient sub-nanoliter sample introduction in laser-induced breakdown spectroscopy and inductively coupled plasma spectrometry: Implications for ultralow sample volumes

Recently, nanoflow nebulizers with low-volume drain-free spray chambers became available for inductively coupled plasma-mass spectrometry application for analysis of very small sampling volumes. The present technical note reports on a different approach for 100% efficient subnanoliter sample introduction, the application of monodisperse piezoelectric microdroplet dispensers which generate 40-50 μa droplets with high reproducibility if nozzles of 30μa diameter are applied. The droplets having volumes below 0.1 nL can be introduced loss-free and without plasma loading, with frequencies up to ∼100 Hz into analytical plasmas. In this technical note, the analytical figures of merit of laser-induced breakdown spectroscopy and inductively coupled plasma-optical emission spectrometry with single droplet introduction are reported using Ca and Au standard solutions as examples. Future engineering is required to reduce the total sample volumes from the relatively large sample reservoir of the current study, thereby reducing potential issues of washout while enabling analysis of ultralow total sample volumes.