Field preconcentration and preservation of sulfide with MOF paper prior to microplasma assisted oxidation gas phase molecular fluorescence spectrometric analysis.

The inherent instability of dissolved sulfide, leading to volatilization and oxidation during transport and storage, significantly compromises the accuracy of its detection. To address this limitation, the highly efficient extraction and preservation of sulfide in the field are essential. Herein, a simple field preconcentration and preservation method using ZIF-8 paper as a monolithic adsorbent coupling to a new dielectric barrier discharge microplasma assisted oxidation gas molecular fluorescence spectrometry was developed for highly sensitive detection of sulfide in environmental samples. The ZIF-8 paper was constructed as a monolithic adsorbent material through the in-situ growth of ZIF-8 on a carboxymethylated filter paper, which facilitates the straightforward and efficient adsorption and desorption of sulfide, offering excellent capability for the field extraction and long-term preservation of sulfide up to five days. The sensitive dielectric barrier discharge microplasma-molecular fluorescence spectrometry detection of sulfide was accomplished with a 3D-printed chemical vapor generation and dielectric barrier discharge microplasma assisted oxidation system. The system was not only employed to convert desorbed sulfide into HS gas, but also used to further oxidize it to SO prior to its introduction to molecular fluorescence spectrometry. Under optimal conditions, the method achieved a limit of detection (LOD) of 0.1 μM and a relative standard deviation (RSD, n = 11) of 5.0 % at 20 μM of sulfide. The accuracy of this method was validated by two certified reference materials and several real environmental water samples. By coupling ZIF-8 paper preconcentration with chemical vapor generation-dielectric barrier discharge microplasma-molecular fluorescence spectrometry, this approach provides enhanced sensitivity, exceptional reliability, and robust performance for sulfide detection in complex environmental water matrices.