Flow injection gas analysis (FIGA) for more sensitive determination of Hg by inductively coupled plasma optical emission spectrometry

Abstract

Aiming at a more sensitive determination of Hg, inductively coupled plasma optical emission spectrometry (ICP OES) was combined with a microplasma-induced vapor generation system operated in a completely new manner, i.e., a flow injection gas analysis (FIGA) mode. In this approach, Hg vapors were accumulatively generated in a closed discharge chamber and after a certain accumulation time (10–120 s), very concentrated vapors were injected from the discharge chamber into an Ar carrier gas entering the ICP torch. This resulted in appearing a time-dependent analytical signal for Hg that was much higher than this acquired for conventional ICP OES with the pneumatic nebulization (PN). The proposed novel method outperformed traditional PN-ICP OES in terms of the detection limit (DL) for Hg, i.e., 0.035 μg L−1versus 5 μg L−1 (140-fold improvement), and measurement precision (2.5% versus 8.3%). Moreover, (FIGA)SAGD-ICP OES offered a 4 times lower DL of Hg than commonly used chemical vapor generation (CVG)-ICP OES (0.15 μg L−1). To validate the trueness of this newly developed method, a certified reference material (CRM) of fish muscle (ERM-BB422) as well as spiked post-leaching solutions of bottom sediment (MODAS-2) and soils were analyzed. An excellent agreement between obtained results and certified values was found (recovery within 97.7–104%), indicating the very good trueness of the FIGA in the more sensitive determination of Hg by ICP OES.