Integration of flow injection-liquid anode glow discharge-fiber spectrometer: A compact analysis system for highly sensitive determination of Hg in water and ore samples

Abstract

A novel liquid anode glow discharge (LAGD) was structured as a miniaturized excitation source of atomic emission spectrometry (AES), and then integrated with flow injection sampler and fiber spectrometer to form a LAGD-AES system for highly sensitive detection of Hg in water and ore samples. Under the optimal operating parameters, Ag+, Al3+, Ga3+, Mn2+, F− and I− ions seriously interfere with the determination of Hg. Adding 1.5% methanol and 5% formic acid can enhance the net signal intensity of Hg about 2.0- and 2.2-fold and markedly reduce the interferences from Ag+, Al3+, Ga3+, Mn2+, F− and I− ions. The detection limit (LOD) of Hg is reduced from 11.3 μg L−1 for no sensitizer to 8.0 μg L−1 for 1.5% methanol and 4.5 μg L−1 for 5% formic acid. The relative standard deviation (RSD, n = 11) for Hg with no sensitizer, adding 1.5% methanol and 5% formic acid are 3.6%, 2.6% and 3.5%, respectively, and the power consumption is about 10 W. The measurement results of spiked water and ore samples are largely consistent with the spiked value and the verification values measured by ICP-AES. The recoveries of water and ore samples are in the range of 88–116% and 101.6–106.3%, respectively. All results suggested that the LAGD-AES can be employed as a promising technique for highly sensitive determination of Hg because of its compact and portable instrument, low energy consumption, high discharge stability, and no inert gas requirement.