Studies on the Determination of Mercury by On-line Solvent Extraction and Non-Aqueous Media Hydride Generation Non-Dispersive Atomic Fluorescence Spectrometry

Abstract.

A new method for on-line solvent extraction covalent hydride generation in a non-aqueous extraction phase is proposed. Both liquid–liquid extraction and gas–liquid separation steps are accomplished in an online mode and with AFS as detector. Hydride generation is carried out in an aliquot of metal-complex extraction solution by sodium tetrahydroborate in N,N-dimethylformamide solution and anhydrous acetic acid. An improved U-type gas–liquid separator was used. The working conditions and manifolds scheme of flow injection were optimized. The detection limit attained for mercury was 20 ng L⁻¹. The precision of the determination at a concentration level of around 20 times the detection limit was 5.6%. The proposed method gives improved sensitivity and eliminates interference. The method has been applied to the determination of mercury in certified reference materials with good accuracy and precision.