Atomic emission spectrometry in liquid electrode plasma using an hourglass microchannel

Abstract

Liquid electrode plasma atomic emission spectrometry (LEP-AES) is a new elemental analysis method that uses microplasma. LEP forms in a vapor bubble generated inside a narrow-center microchannel by using high-voltage DC pulse power. In this study, we used a novel hourglass microchannel having a 3-dimensionally and axisymmetrically narrowed shape, which caused a bright emission roughly 200 times that of the flat microchannel used in our previous study. We observed the spatial distribution of atomic emission and determined the limit of detection (LoD) by utilizing the confirmed spatial distribution. We found that the spatial distribution of atomic emission for 41 elements in our experiments could be classified into three patterns in accordance with a maximum emission point: anode side, narrow-center, and cathode side. Atomic emission was measured at the maximum emission point and the calibration curve for each element was made to determine the LoD. The LoD of 25 tested elements in our experiment ranged from 1 μg L⁻¹ for Li to 306 μg L⁻¹ for V.