Mercury vapor generation using a non-equilibrium cold atmospheric plasma jet for mercury determination equipped with atomic absorption spectrometry.

Cold vapor atomic absorption spectrometry (CV-AAS) is a cost-effective and simple technique for determining mercury (Hg). However, it typically requires milligram amounts of another toxic heavy metal, tin (Sn). We developed a novel Hg determination method that integrates a low-temperature atmospheric-pressure plasma jet for Hg atomization with an atomic absorption spectrometer, and called it plasma-mediated vapor generation AAS (PMVG-AAS). Unlike conventional CV-AAS, this method does not require Sn because plasma-generated reactive species reduce Hg ions to elemental Hg. An exchangeable insert cup is set in the analysis chamber to facilitate efficient reactions between the liquid sample and the reactive species while preventing cross-contamination. After optimizing key experimental parameters, including plasma source gas, sampling temperature, sample volume, and the distance between plasma and sample surface, a linear calibration curve is obtained. The limit of detection (LOD) and the limit of quantification (LOQ) for inorganic Hg are 0.42 ng mL-1 and 1.41 ng mL-1, respectively, lower than previously reported values for other PMVG-AAS systems. The present PMVG-AAS method accurately determined total Hg in acid-digested samples. Additionally, it directly determined both inorganic Hg and methylmercury in undigested urine, seawater-mimicking high-salt solutions, and highly acidic solutions, with an error of less than 8%. The PMVG-AAS method demonstrates improved tolerance toward both organic and inorganic matrices compared with conventional CV-AAS, while maintaining high precision and accuracy in the determination of Hg in liquid samples.