Ultra-sensitive determination of mercury by atmospheric pressure glow discharge atomic emission spectrometry coupled with cold vapor generation

Abstract

In this work, a highly sensitive method for the determination of mercury was developed, based on direct-current atmospheric pressure glow discharge in helium (He) atomic emission spectroscopy (APGD-AES) coupled with cold vapor generation (CVG). The mercury vapor generated by CVG was transmitted to APGD through capillary for excitation, and the signal was recorded by a micro-spectrometer. The parameters of CVG and APGD systems were optimized, including NaBH₄ concentration, hydrochloric acid concentration, He flow rate, discharge current and discharge gap. Under the optimum operating conditions, the detection limit (DL) of Hg was 0.26 μg L⁻¹, and the relative standard deviation (RSD) was 0.7% (n = 11, 50 μg L⁻¹). In the concentration range of 4–100 μg L⁻¹, the linear correlation coefficient was better than 0.999. The accuracy and practicality of CVG-APGD-AES were verified by the analysis of the GBW10029 (fish) certified reference material (CRM) and human hair samples. The results were consistent with those of a direct mercury analysis (DMA) system and the certified value (relative deviation was less than 3%).