Signal enhancement in solution-cathode glow discharge — optical emission spectrometry via low molecular weight organic compounds

Abstract

HCOOH, CH3COOH, and CH3CH2OH were used as chemical modifiers in a solution-cathode glow discharge. Emission was measured directly from the discharge, without a gas–liquid separator or a secondary excitation source. Emission from Ag, Se, Pb, and Hg was strongly enhanced, and the detection limits (DL) for these elements were improved by up to an order of magnitude using a combination of HCOOH and HNO3 compared to using HNO3 alone. The DL was measured for Mg (1μg/L), Fe (10μg/L), Ni (6μg/L), Cu (6μg/L), Pb (1μg/L), Ag (0.1μg/L), Se (300μg/L), and Hg (2μg/L). Coefficients of determination (R2) were between 0.9986 and 0.9999. A voltage of 1kV was used, which produced a current of approximately 70mA.