Co²⁺ - assisted continuous flow UV-induced Hg vapor generation coupled with a modified MSIS gas–liquid separator and microwave plasma atomic emission spectrometry

Co²⁺ and Ni²⁺ were investigated as potential sensitizers for the continuous flow UV-induced Hg vapor generation utilizing 10% (v/v) HCOOH as a low-molecular weight carboxylic acid and a modified multimode sample introduction system (MSIS) as a gas–liquid separator (GLS) coupled with microwave plasma atomic emission spectrometry (MP-AES). In contrast with Co²⁺, Ni²⁺ was found to suppress the sensitivity at different concentration levels. Thus, Co²⁺ was selected as a suitable sensitivity enhancement reagent and its concentration (1.50 mg dm⁻³) was optimized improving the empirical and the instrumental limit of detection (LOD) for Hg²⁺ to 0.10 µg dm⁻³ and 0.01 µg dm⁻³, respectively. The possible reasons for the observed effects of Co²⁺ and Ni²⁺ on the sensitivity were discussed. The Co²⁺—assisted UV-induced Hg vapor generation coupled with the modified MSIS GLS and MP-AES provided significantly lower instrumental LOD (ILOD) in comparison with other hyphenated Hg vapor generation procedures in the atomic spectrometry previously reported in the literature.